DS26900

DS26900 MAXIM | Alldatasheet

Document overview

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Technical content

Features

♦ Efficient Solution for Star Architecture JTAG ♦ Provides Transparent Communications Between the Arbitrated Master and a Selected Secondary Port ♦ Single-Package Solution Provides 18 Secondary Ports ♦ Two-Package Cascade Configuration Provides 36 Secondary Ports ♦ Three Arbitrated Master Ports ♦ Autodetection of Port Presence ♦ Internal Pullup/Down Resistors ♦ Two 32-Bit Scratchpad Registers ♦ Four GPIO Pins for Read/Write Control and Signaling Applications ♦ Operation Up to 50MHz ♦ Signal Path Modification Options ♦ Redundancy with High-Impedance Pin ♦ Independent Periphery JTAG ♦ Configuration Mode Uses IEEE 1149.1 TAP Controller ♦ Supports Live Insertion/Withdrawal ♦ 3.3V Operation ♦ Industrial Temperature Operation ♦ RoHS-Compliant Packaging

Ordering Information

PART TEMP RANGE PIN-PACKAGE DS26900N+ -40°C to +85°C 144 LQFP +Denotes a lead-free package. Rev: 072707

1. Block Diagram Figure 1-1. DS26900 Block Diagram SECONDARY 1 SECONDARY 2 SECONDARY 3 SECONDARY 4 SECONDARY 18 PORT MUX SWITCH LOGIC SWITCH TAP CONTROLLER PERIPHERY TAP CONTROLLER MASTER ARBITER REGISTER BANK EXTERNAL TEST PORT TEST MASTER PORT 1 GPIO [3:0] SSPI [4:0] PROG INVERSIONS MODE [1:0] JTAG 5 ACT MCI MGNT TEST MASTER PORT 2 DS26900

1. Pin Descriptions Table 2-1. Pin Descriptions (Sorted by Function) NAME PIN TYPE FUNCTION ETCK 4 Ipd External Test Master Clock. In configuration mode, a falling edge on this pin clocks data in on the ETDI pin. A falling edge on this pin clocks data out on the ETDO pin. When PREN = VDD, a 20kΩ pulldown resistor is connected to this pin. ETDI 2 Ipd External Test Master Serial Data Input. In configuration mode, data is clocked in on this pin on the falling edge of ETCK. When PREN = VDD, a 20kΩ pulldown resistor is connected to this pin. ETDO 3 High Impedance External Test Master Serial Data Out. (High Impedance) Data is clocked out on this pin on the falling edge of ETCK. When PREN = V DD, a 10kΩ pullup resistor is connected to this pin. ECFG 5 Ipu External Test Master Configuration (Active Low). Asserting this pin low along with EREQ asserted low allows the External Test Master to configure the DS26900, allowing access to the Switch TAP Controller. Toggling ECFG when EREQ is high has no effect. When PREN = VDD, a 10kΩ pullup resistor is connected to this pin. ETMS 6 Ipu External Test Master Test Mode Select. This pin is sampled on the rising edge of ETCK and is used to place the port into the various defined IEEE 1149.1 states. When PREN = VDD, a 10kΩ pullup resistor is connected to this pin. EREQ 1 Ipu External Test Master Request (Active Low). (Internal 10kΩ Pullup) When active, this pin selects the external test port as the master. When switching EREQ, none of the master clocks should be toggling. MGNT0 144 O Master Grant 0 (Active Low). Asserted low when the external test master is the arbitrated master. TCK1 22 Ipd/O Test Master 1 Test Port Clock Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 20kΩ pulldown resistor is connected to this pin. TDI1 20 Ipu/O Test Master 1 Test Port Serial Data Input Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TDO1 21 I/O Test Master 1 Test Port Serial Data Out Master Mode = Output Slave Mode = Input When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TRST1 23 Ipu/O Test Master 1 Test Port Test Reset (Active Low). Asserting this pin low (when master) puts the DS26900 into configuration mode, allowing access to the Switch TAP Controller. Toggling TRST1 when not the arbitrated master has no effect. This pin does not directly affect secondary port resets. Master Mode = TRST1 Input Slave Mode = TRST1 Output When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin.

Test Master 1 Test Port Test Mode Select Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 20kΩ pulldown resistor is connected to this pin. TMREQ1 19 Ipu Test Master 1 Master Request (Active Low). (Internal 10kΩ Pullup) When EREQ is inactive and TMREQ1 is active, this pin selects the test master port 1 as the master. When switching TMREQ1, none of the master clocks should be toggling. MGNT1 18 O Master Grant 1 (Active Low). Asserted low when Test Master 1 is the arbitrated master. TCK2 30 Ipd/O Test Master 2 Test Port Clock Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 20kΩ pulldown resistor is connected to this pin. TDI2 28 Ipu/O Test Master 2 Test Port Serial Data Input Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TDO2 29 I/O Test Master 2 Test Port Serial Data Out Master Mode = Output Slave Mode = Input When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TRST2 31 Ipu/O Test Master 2 Test Port Test Reset (Active Low). Asserting this pin low (when master) puts the DS26900 into configuration mode, allowing access to the Switch TAP Controller. Toggling TRST2 when not the arbitrated master has no effect. This pin does not directly affect secondary port resets. Master Mode = TRST2 Input Slave Mode = TRST2 Output When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TMS2 32 Ipd/O Test Master 2 Test Port Test Mode Select Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 20kΩ pulldown resistor is connected to this pin. TMREQ2 27 Ipu Test Master 2 Master Request (Active Low) (Internal 10kΩ Pullup) When EREQ and TMREQ1 are inactive and TMREQ2 is active, this pin selects the test master port 2 as the master. When switching TMREQ2, none of the master clocks should be toggling. MGNT2 25 O Master Grant 2 (Active Low). Asserted low when Test Master 2 is the arbitrated master. STCK1 91 O Secondary Port 1 Test Clock STDI1 92 O Secondary Port 1 Serial Data In STDO1 93 Ipu Secondary Port 1 Serial Data Out (Internal 10kΩ Pullup) STRST1 90 O Secondary Port 1 Test Reset (Active Low) STMS1 89 O Secondary Port 1 Test Mode Select (Internal 20kΩ Pulldown) STCK2 86 O Secondary Port 2 Test Clock STDI2 87 O Secondary Port 2 Serial Data Input STDO2 88 Ipu Secondary port 2 Serial Data Out (Internal 10kΩ Pullup) STRST2 85 O Secondary Port 2 Test Reset (Active Low)

STMS2 84 O Secondary Port 2 Test Mode Select (Internal 20kΩ Pulldown) STCK3 80 O Secondary Port 3 Test Clock STDI3 81 O Secondary Port 3 Serial Data Input STDO3 82 Ipu Secondary Port 3 Serial Data Out (Internal 10kΩ Pullup) STRST3 79 O Secondary Port 3 Test Reset (Active Low) STMS3 78 O Secondary Port 3 Test Mode Select (Internal 20kΩ Pulldown) STCK4 75 O Secondary Port 4 Test Clock STDI4 76 O Secondary Port 4 Serial Data Input STDO4 77 Ipu Secondary Port 4 Serial Data Out (Internal 10kΩ Pullup) STRST4 74 O Secondary Port 4 Test Reset (Active Low) STMS4 73 O Secondary Port 4 Test Mode Select (Internal 20kΩ Pulldown) STCK5 70 O Secondary Port 5 Test Clock STDI5 71 O Secondary Port 5 Serial Data Input STDO5 72 Ipu Secondary Port 5 Serial Data Out (Internal 10kΩ Pullup) STRST5 69 O Secondary Port 5 Test Reset (Active Low) STMS5 68 O Secondary Port 5 Test Mode Select (Internal 20kΩ Pulldown) STCK6 65 O Secondary Port 6 Test Clock STDI6 66 O Secondary Port 6 Serial Data Input STDO6 67 Ipu Secondary Port 6 Serial Data Out (Internal 10kΩ Pullup) STRST6 64 O Secondary Port 6 Test Reset (Active Low) STMS6 63 O Secondary Port 6 Test Mode Select (Internal 20kΩ Pulldown) STCK7 59 O Secondary Port 7 Test Clock STDI7 60 O Secondary Port 7 Serial Data Input STDO7 61 Ipu Secondary Port 7 Serial Data Out (Internal 10kΩ Pullup) STRST7 58 O Secondary Port 7 Test Reset (Active Low) STMS7 57 O Secondary Port 7 Test Mode Select (Internal 20kΩ Pulldown) STCK8 54 O Secondary Port 8 Test Clock STDI8 55 O Secondary Port 8 Serial Data Input STDO8 56 Ipu Secondary Port 8 Serial Data Out (Internal 10kΩ Pullup) STRST8 53 O Secondary Port 8 Test Reset (Active Low) STMS8 52 O Secondary Port 8 Test Mode Select (Internal 20kΩ Pulldown) STCK9 49 O Secondary Port 9 Test Clock STDI9 50 O Secondary Port 9 Serial Data Input STDO9 51 Ipu Secondary Port 9 Serial Data Out (Internal 10kΩ Pullup) STRST9 47 O Secondary Port 9 Test Reset (Active Low) STMS9 46 O Secondary Port 9 Test Mode Select (Internal 20kΩ Pulldown) STCK10 43 O Secondary Port 10 Test Clock STDI10 44 O Secondary Port 10 Serial Data Input STDO10 45 Ipu Secondary Port 10 Serial Data Out (Internal 10kΩ Pullup) STRST10 42 O Secondary Port 10 Test Reset (Active Low) STMS10 41 O Secondary Port 10 Test Mode Select (Internal 20kΩ Pulldown)

STCK11 138 O Secondary Port 11 Test Clock STDI11 139 O Secondary Port 11 Serial Data Input STDO11 140 Ipu Secondary Port 11 Serial Data Out (internal 10k pullup) STRST11 137 O Secondary Port 11 Test Reset (Active Low) STMS11 136 O Secondary Port 11 Test Mode Select (Internal 20kΩ Pulldown) STCK12 132 O Secondary Port 12 Test Clock STDI12 134 O Secondary Port 12 Serial Data Input STDO12 135 Ipu Secondary Port 12 Serial Data Out (Internal 10kΩ Pullup) STRST12 131 O Secondary Port 12 Test Reset (Active Low) STMS12 130 O Secondary Port 12 Test Mode Select (Internal 20kΩ Pulldown) STCK13 127 O Secondary Port 13 Test Clock STDI13 128 O Secondary Port 13 Serial Data Input STDO13 129 Ipu Secondary Port 13 Serial Data Out (Internal 10kΩ Pullup) STRST13 126 O Secondary Port 13 Test Reset (Active Low) STMS13 125 O Secondary Port 13 Test Mode Select (Internal 20kΩ Pulldown) STCK14 122 O Secondary Port 14 Test Clock STDI14 123 O Secondary Port 14 Serial Data Input STDO14 124 Ipu Secondary Port 14 Serial Data Out (Internal 10kΩ Pullup) STRST14 121 O Secondary Port 14 Test Reset (Active Low) STMS14 120 O Secondary Port 14 Test Mode Select (Internal 20kΩ Pulldown) STCK15 116 O Secondary Port 15 Test Clock STDI15 117 O Secondary Port 15 Serial Data Input STDO15 118 Ipu Secondary Port 15 Serial Data Out (Internal 10kΩ Pullup) STRST15 115 O Secondary Port 15 Test Reset (Active Low) STMS15 114 O Secondary Port 15 Test Mode Select (Internal 20kΩ Pulldown) STCK16 111 O Secondary Port 16 Test Clock STDI16 112 O Secondary Port 16 Serial Data Input STDO16 113 Ipu Secondary Port 16 Serial Data Out (internal 10k pullup) STRST16 110 O Secondary Port 16 Test Reset (Active Low) STMS16 109 O Secondary Port 16 Test Mode Select (Internal 20kΩ Pulldown) STCK17 105 O Secondary Port 17 Test Clock STDI17 106 O Secondary Port 17 Serial Data Input STDO17 107 Ipu Secondary Port 17 Serial Data Out (Internal 10kΩ Pullup) STRST17 104 O Secondary Port 17 Test Reset (Active Low) STMS17 103 O Secondary Port 17 Test Mode Select (Internal 20kΩ Pulldown) STCK18 100 O Secondary Port 18 Test Clock STDI18 101 O Secondary Port 18 Serial Data Input STDO18 102 Ipu Secondary Port 18 Serial Data Out (Internal 10kΩ Pullup) STRST18 99 O Secondary Port 18 Test Reset (Active Low) STMS18 98 O Secondary Port 18 Test Mode Select (Internal 20kΩ Pulldown) N.C. 94, 95 — No Connection

Selected Secondary Port Indicator Bit 4 (Active Low). Along with pins SSPI3, SSPI2, SSPI1, and SSPI0, this pin provides a hardware indication of the selected secondary port. See Table 7-2 for more information. SSPI3 9 O Selected Secondary Port Indicator Bit 3 (Active Low). Along with pins SSPI4, SSPI2, SSPI1, and SSPI0, this pin provides a hardware indication of the selected secondary port. See Table 7-2 for more information. SSPI2 10 O Selected Secondary Port Indicator Bit 2 (Active Low). Along with pins SSPI4, SSPI3, SSPI1, and SSPI0, this provides a hardware indication of the selected secondary port. See Table 7-2 for more information. SSPI1 11 O Selected Secondary Port Indicator Bit 1 (Active Low). Along with pins SSPI4, SSPI3, SSPI2, and SSPI0, this pin provides a hardware indication of the selected secondary port. See Table 7-2 for more information. SSPI0 12 O Selected Secondary Port Indicator Bit 0 (Active Low). Along with pins SSPI4, SSPI3, SSPI2, and SSPI1, this pin provides a hardware indication of the selected secondary port. See Table 7-2 for more information. GPIO[3] 14 Ipd/O General-Purpose Input/Output Bit 3. (Internal 20kΩ Pulldown) This pin is a general- purpose input/output, which can be read or driven via a register bit. This pin is in input mode after a global reset. GPIO[2] 15 Ipd/O General-Purpose Input/Output Bit 2. (Internal 20kΩ Pulldown) This pin is a general- purpose input/output, which can be read or driven via a register bit. This pin is in input mode after a global reset. GPIO[1] 16 Ipd/O General-Purpose Input/Output Bit 1. (Internal 20kΩ Pulldown) This pin is a general- purpose input/output, which can be read or driven via a register bit. This pin is in input mode after a global reset. GPIO[0] 17 Ipd/O General-Purpose Input/Output Bit 0. (Internal 20kΩ Pulldown) This pin is a general- purpose input/output, which can be read or driven via a register bit. This pin is in input mode after a global reset. RST 33 Ipu Global Reset (Active Low). (Internal 10kΩ Pullup) A low state on this pin provides an asynchronous reset for global registers and logic. RST should be tied high for normal operation. TEST 62 Ipu Test Enable (Active Low). (Internal 10kΩ Pullup) Factory test input. TEST must be tied high or unconnected for normal operation. HIZ 143 I Output High-Impedance Enable (Active Low). When this pin is asserted low, internal pullup and pulldown resistors are disabled, all outputs are put into high- impedance mode, and master request inputs (EREQ, TMREQ1, TMREQ2) are disabled. PTRST must also be asserted logic 0. M[1] 141 Ipd Mode Select Bit 1. (Internal 20kΩ Pulldown) Selects mode of operation of the device (Single-Package, Cascade-Master, Cascade-Extension, or Deselect. M[0] 142 Ipd Mode Select Bit 0. (Internal 20kΩ Pulldown) Selects mode of operation of the device (Single-Package, Cascade-Master, Cascade-Extension, or Deselect). MCI 34 O Master Conflict Indicator (Active Low). Indicates that more than one device is requesting to be master. Asserted low when more than one of the EREQ, TMREQ1, or TMREQ2 signals is asserted low. DPDV 96 O Deselected Port Data Value. This pin directly indicates the state of the DPDV bit in the Device Configuration Register (DCR). PTCK 40 I Periphery JTAG Chain Test Clock. This input must be driven to a logic level during normal operation. PTDI 39 I Periphery JTAG Chain Serial Data Input. This input must be driven to a logic level during normal operation. PTDO 38 O Periphery JTAG Chain Serial Data Out

PTRST 37 I Periphery JTAG Chain Test Reset (Active Low). During normal operation, this signal is asserted low. PTMS 35 Ipu Periphery JTAG Chain Test Mode Select. This input must be driven to a logic level during normal operation. ACT 97 O Active (Active Low). Indicates that this device is active when low. An active device is determined by the MSB of the instruction code and the state of the mode pins M0 and M1. PREN 7 I Pull-Resistor Enable. When connected to VDD, the following pull resistors are enabled: 20kΩ pulldown on TCK1, TCK2, ETDI, ETCK, TMS1, TMS2 10kΩ pullup on TDI1, TDI2, ETDO, TDO1, TDO2, TRST1, TRST2, ECFG, ETMS When connected to VSS, the pull resistors on the signals above are disabled. When multiple devices are connected in parallel only one device should have PREN connected = VDD. VDD 13, 36, 83, 119 P Positive Supply. 3.3V ±5%. All VDD signals should be tied together. VSS 26, 48, 108, 133 P Ground Reference. All VSS signals should be tied together. Configuration Mode. The master is communicating with the Switch TAP Controller in the DS26900. Transparent Mode. The master is communicating directly with the selected secondary port. All pins are I/O in periphery JTAG mode except the TEST, TMREQ1, TMREQ2, EREQ, M1, M0, HIZ, RST, PTRST, PTCK, PTDI, PTDO, and PTMS pins. All outputs are rated at 8mA. Unused inputs must be tied to logic 1 or 0 if not used and a pullup/pulldown is not present. O = Output I = Input Ipu = Input with an internal pullup Ipd = Input with an internal pulldown P = Power

Table 2-2. Pin Description (Sorted by Pin Number) NAME PIN TYPE FUNCTION EREQ 1 Ipu External Test Master Request (Active Low). (Internal 10kΩ Pullup) When active, this pin selects the external test port as the master. When switching EREQ, none of the master clocks should be toggling. ETDI 2 Ipd External Test Master Serial Data Input. In configuration mode, data is clocked in on this pin on the falling edge of ETCK. When PREN = VDD, a 20kΩ pulldown resistor is connected to this pin. ETDO 3 High Impedance External Test Master Serial Data Out. (High Impedance) Data is clocked out on this pin on the falling edge of ETCK. When PREN = V DD, a 10kΩ pullup resistor is connected to this pin. ETCK 4 Ipd External Test Master Clock. In configuration mode, a falling edge on this pin clocks data in on the ETDI pin. A falling edge on this pin clocks data out on the ETDO pin. When PREN = VDD, a 20kΩ pulldown resistor is connected to this pin. ECFG 5 Ipu External Test Master Configuration (Active Low). Asserting this pin low along with EREQ asserted low allows the External Test Master to configure the DS26900, allowing access to the Switch TAP Controller. Toggling ECFG when EREQ is high has no effect. When PREN = V DD, a 10kΩ pullup resistor is connected to this pin. ETMS 6 Ipu External Test Master Test Mode Select. This pin is sampled on the rising edge of ETCK and is used to place the port into the various defined IEEE 1149.1 states. When PREN = VDD, a 10kΩ pullup resistor is connected to this pin. PREN 7 I Pull-Resistor Enable. When connected to VDD, the following pull resistors are enabled: 20kΩ pulldown on TCK1, TCK2, ETDI, ETCK, TMS1, TMS2 10kΩ pullup on TDI1, TDI2, ETDO, TDO1, TDO2, TRST1, TRST2, ECFG, ETMS When connected to VSS, the pull resistors on the signals above are disabled. When multiple devices are connected in parallel only one device should have PREN connected = VDD. SSPI4 8 O Selected Secondary Port Indicator Bit 4 (Active Low). Along with pins SSPI3, SSPI2, SSPI1 and SSPI0, provides a hardware indication of the selected secondary port. See Table 7-2 for more information. SSPI3 9 O Selected Secondary Port Indicator Bit 3 (Active Low). Along with pins SSPI4, SSPI2, SSPI1 and SSPI0, provides a hardware indication of the selected secondary port. See Table 7-2 for more information. SSPI2 10 O Selected Secondary Port Indicator Bit 2 (Active Low). Along with pins SSPI4, SSPI3, SSPI1 and SSPI0, provides a hardware indication of the selected secondary port. See Table 7-2 for more information. SSPI1 11 O Selected Secondary Port Indicator Bit 1 (Active Low). Along with pins SSPI4, SSPI3, SSPI2 and SSPI0, provides a hardware indication of the selected secondary port. See Table 7-2 for more information. SSPI0 12 O Selected Secondary Port Indicator Bit 0 (Active Low). Along with pins SSPI4, SSPI3, SSPI2 and SSPI1, provides a hardware indication of the selected secondary port. See Table 7-2 for more information. VDD 13, 36, 83, 119 P Positive Supply. 3.3V ±5%. All VDD signals should be tied together. GPIO[3] 14 Ipd/O General-Purpose Input/Output Bit 3. (Internal 20kΩ Pulldown) This pin is a general- purpose input/output, which can be read or driven via a register bit. This pin is in input mode after a global reset.

GPIO[2] 15 Ipd/O General-Purpose Input/Output Bit 2. (Internal 20kΩ Pulldown) This pin is a general- purpose input/output, which can be read or driven via a register bit. This pin is in input mode after a global reset. GPIO[1] 16 Ipd/O General-Purpose Input/Output Bit 1. (Internal 20kΩ Pulldown) This pin is a general- purpose input/output, which can be read or driven via a register bit. This pin is in input mode after a global reset. GPIO[0] 17 Ipd/O General-Purpose Input/Output Bit 0. (Internal 20kΩ Pulldown) This pin is a general- purpose input/output, which can be read or driven via a register bit. This pin is in input mode after a global reset. MGNT1 18 O Master Grant 1 (Active Low). Asserted low when Test Master 1 is the arbitrated master. TMREQ1 19 Ipu Test Master 1 Master Request (Active Low). (Internal 10kΩ Pullup) When EREQ is inactive and TMREQ1 is active, this pin selects the test master port 1 as the master. When switching TMREQ1, none of the master clocks should be toggling. TDI1 20 Ipu/O Test Master 1 Test Port Serial Data Input Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TDO1 21 I/O Test Master 1 Test Port Serial Data Out Master Mode = Output Slave Mode = Input When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TCK1 22 Ipd/O Test Master 1 Test Port Clock Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 20kΩ pulldown resistor is connected to this pin. TRST1 23 Ipu / O Test Master 1 Test Port Test Reset (Active Low). Asserting this pin low (when master) puts the DS26900 into configuration mode, allowing access to the Switch TAP Controller. Toggling TRST1 when not the arbitrated master has no effect. This pin does not directly affect secondary port resets. Master Mode = TRST1 Input Slave Mode = TRST1 Output When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TMS1 24 Ipd/O Test Master 1 Test Port Test Mode Select Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 20kΩ pulldown resistor is connected to this pin. MGNT2 25 O Master Grant 2 (Active Low). Asserted low when Test Master 2 is the arbitrated master. VSS 26, 48, 108, 133 P Ground Reference. All VSS signals should be tied together. TMREQ2 27 Ipu Test Master 2 Master Request (Active Low). (Internal 10kΩ Pullup) When EREQ and TMREQ1 are inactive and TMREQ2 is active, this pin selects the test master port 2 as the master. When switching TMREQ2, none of the master clocks should be toggling. TDI2 28 Ipu/O Test Master 2 Test Port Serial Data Input Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin.

Test Master 2 Test Port Serial Data Out Master Mode = Output Slave Mode = Input When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TCK2 30 Ipd/O Test Master 2 Test Port Clock Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 20kΩ pulldown resistor is connected to this pin. TRST2 31 Ipu/O Test Master 2 Test Port Test Reset (Active Low). Asserting this pin low (when master) puts the DS26900 into configuration mode, allowing access to the Switch TAP Controller. Toggling TRST2 when not the arbitrated master has no effect. This pin does not directly affect secondary port resets. Master Mode = TRST2 Input Slave Mode = TRST2 Output When PREN = VDD, an internal 10kΩ pullup resistor is connected to this pin. TMS2 32 Ipd/O Test Master 2 Test Port Test Mode Select Master Mode = Input Slave Mode = Output When PREN = VDD, an internal 20kΩ pulldown resistor is connected to this pin. RST 33 Ipu Global Reset (Active Low). (Internal 10kΩ Pullup) A low state on this pin provides an asynchronous reset for global registers and logic. RST should be tied high for normal operation. MCI 34 O Master Conflict Indicator (Active Low). Indicates that more than one device is requesting to be master. Asserted low when more than one of the EREQ, TMREQ1, or TMREQ2 signals is asserted low. PTMS 35 Ipu Periphery JTAG Chain Test Mode Select. This input must be driven to a logic level during normal operation. PTRST 37 I Periphery JTAG Chain Test Reset (Active Low). During normal operation, this signal is asserted low. PTDO 38 O Periphery JTAG Chain Serial Data Out PTDI 39 I Periphery JTAG Chain Serial Data Input. This input must be driven to a logic level during normal operation. PTCK 40 I Periphery JTAG Chain Test Clock. This input must be driven to a logic level during normal operation. STMS10 41 O Secondary Port 10 Test Mode Select (Internal 20kΩ Pulldown) STRST10 42 O Secondary Port 10 Test Reset (Active Low) STCK10 43 O Secondary Port 10 Test Clock STDI10 44 O Secondary Port 10 Serial Data Input STDO10 45 Ipu Secondary Port 10 Serial Data Out (Internal 10kΩ Pullup) STMS9 46 O Secondary Port 9 Test Mode Select (Internal 20kΩ Pulldown) STRST9 47 O Secondary Port 9 Test Reset (Active Low) STCK9 49 O Secondary Port 9 Test Clock STDI9 50 O Secondary Port 9 Serial Data Input STDO9 51 Ipu Secondary Port 9 Serial Data Out (Internal 10kΩ Pullup) STMS8 52 O Secondary Port 8 Test Mode Select (Internal 20kΩ Pulldown) STRST8 53 O Secondary Port 8 Test Reset (Active Low)

STCK8 54 O Secondary Port 8 Test Clock STDI8 55 O Secondary Port 8 Serial Data Input STDO8 56 Ipu Secondary Port 8 Serial Data Out (Internal 10kΩ Pullup) STMS7 57 O Secondary Port 7 Test Mode Select (Internal 20kΩ Pulldown) STRST7 58 O Secondary Port 7 Test Reset (Active Low) STCK7 59 O Secondary Port 7 Test Clock STDI7 60 O Secondary Port 7 Serial Data Input STDO7 61 Ipu Secondary Port 7 Serial Data Out (Internal 10kΩ Pullup) TEST 62 Ipu Test Enable (Active Low). (Internal 10kΩ Pullup) Factory test input. TEST must be tied high or unconnected for normal operation. STMS6 63 O Secondary Port 6 Test Mode Select (Internal 20kΩ Pulldown) STRST6 64 O Secondary Port 6 Test Reset (Active Low) STCK6 65 O Secondary Port 6 Test Clock STDI6 66 O Secondary Port 6 Serial Data Input STDO6 67 Ipu Secondary Port 6 Serial Data Out (Internal 10kΩ Pullup) STMS5 68 O Secondary Port 5 Test Mode Select (Internal 20kΩ Pulldown) STRST5 69 O Secondary Port 5 Test Reset (Active Low) STCK5 70 O Secondary Port 5 Test Clock STDI5 71 O Secondary Port 5 Serial Data Input STDO5 72 Ipu Secondary Port 5 Serial Data Out (Internal 10kΩ Pullup) STMS4 73 O Secondary Port 4 Test Mode Select (Internal 20kΩ Pulldown) STRST4 74 O Secondary Port 4 Test Reset (Active Low) STCK4 75 O Secondary Port 4 Test Clock STDI4 76 O Secondary Port 4 Serial Data Input STDO4 77 Ipu Secondary Port 4 Serial Data Out (Internal 10kΩ Pullup) STMS3 78 O Secondary Port 3 Test Mode Select (Internal 20kΩ Pulldown) STRST3 79 O Secondary Port 3 Test Reset (Active Low) STCK3 80 O Secondary Port 3 Test Clock STDI3 81 O Secondary Port 3 Serial Data Input STDO3 82 Ipu Secondary Port 3 Serial Data Out (Internal 10kΩ Pullup) STMS2 84 O Secondary Port 2 Test Mode Select (Internal 20kΩ Pulldown) STRST2 85 O Secondary Port 2 Test Reset (Active Low) STCK2 86 O Secondary Port 2 Test Clock STDI2 87 O Secondary Port 2 Serial Data Input STDO2 88 Ipu Secondary port 2 Serial Data Out (Internal 10kΩ Pullup) STMS1 89 O Secondary Port 1 Test Mode Select (Internal 20kΩ Pulldown) STRST1 90 O Secondary Port 1 Test Reset (Active Low) STCK1 91 O Secondary Port 1 Test Clock STDI1 92 O Secondary Port 1 Serial Data In STDO1 93 Ipu Secondary Port 1 Serial Data Out (Internal 10kΩ Pullup) N.C. 94, 95 — No Connection DPDV 96 O Deselected Port Data Value. This pin directly indicates the state of the DPDV bit in the Device Configuration Register (DCR).

Active (Active Low). Indicates that this device is active when low. An active device is determined by the MSB of the instruction code and the state of the M0, M1 mode pins. STMS18 98 O Secondary Port 18 Test Mode Select (Internal 20kΩ Pulldown) STRST18 99 O Secondary Port 18 Test Reset STCK18 100 O Secondary Port 18 Test Clock STDI18 101 O Secondary Port 18 Serial Data Input STDO18 102 Ipu Secondary Port 18 Serial Data Out (Internal 10kΩ Pullup) STMS17 103 O Secondary Port 17 Test Mode Select (Internal 20kΩ Pulldown) STRST17 104 O Secondary Port 17 Test Reset (Active Low) STCK17 105 O Secondary Port 17 Test Clock STDI17 106 O Secondary Port 17 Serial Data Input STDO17 107 Ipu Secondary Port 17 Serial Data Out (Internal 10kΩ Pullup) STMS16 109 O Secondary Port 16 Test Mode Select (Internal 20kΩ Pulldown) STRST16 110 O Secondary Port 16 Test Reset (Active Low) STCK16 111 O Secondary Port 16 Test Clock STDI16 112 O Secondary Port 16 Serial Data Input STDO16 113 Ipu Secondary Port 16 Serial Data Out (Internal 10kΩ Pullup) STMS15 114 O Secondary Port 15 Test Mode Select (Internal 20kΩ Pulldown) STRST15 115 O Secondary Port 15 Test Reset (Active Low) STCK15 116 O Secondary Port 15 Test Clock STDI15 117 O Secondary Port 15 Serial Data Input STDO15 118 Ipu Secondary Port 15 Serial Data Out (Internal 10kΩ Pullup) STMS14 120 O Secondary Port 14 Test Mode Select (Internal 20kΩ Pulldown) STRST14 121 O Secondary Port 14 Test Reset (Active Low) STCK14 122 O Secondary Port 14 Test Clock STDI14 123 O Secondary Port 14 Serial Data Input STDO14 124 Ipu Secondary Port 14 Serial Data Out (Internal 10kΩ Pullup) STMS13 125 O Secondary Port 13 Test Mode Select (Internal 20kΩ Pulldown) STRST13 126 O Secondary Port 13 Test Reset (Active Low) STCK13 127 O Secondary Port 13 Test Clock STDI13 128 O Secondary Port 13 Serial Data Input STDO13 129 Ipu Secondary Port 13 Serial Data Out (Internal 10kΩ Pullup) STMS12 130 O Secondary Port 12 Test Mode Select (Internal 20kΩ Pulldown) STRST12 131 O Secondary Port 12 Test Reset (Active Low) STCK12 132 O Secondary Port 12 Test Clock STDI12 134 O Secondary Port 12 Serial Data Input STDO12 135 Ipu Secondary Port 12 Serial Data Out (Internal 10kΩ Pullup) STMS11 136 O Secondary Port 11 Test Mode Select (Internal 20kΩ Pulldown) STRST11 137 O Secondary Port 11 Test Reset (Active Low) STCK11 138 O Secondary Port 11 Test Clock STDI11 139 O Secondary Port 11 Serial Data Input STDO11 140 Ipu Secondary Port 11 Serial Data Out (Internal 10kΩ Pullup)

M[1] 141 Ipd Mode Select Bit 1. (Internal 20kΩ Pulldown) Selects mode of operation of the device (Single-Package, Cascade-Master, Cascade-Extension, or Deselect). M[0] 142 Ipd Mode Select Bit 0. (Internal 20kΩ Pulldown) Selects mode of operation of the device (Single-Package, Cascade-Master, Cascade-Extension, or Deselect). HIZ 143 I Output High-Impedance Enable (Active Low). When this pin is asserted low, internal pullup and pulldown resistors are disabled, all outputs are put into high impedance mode, and master request inputs (EREQ, TMREQ1, TMREQ2) are disabled. PTRST must also be asserted logic 0. MGNT0 144 O Master Grant 0 (Active Low). Asserted low when the External Test Master is the arbitrated master. Configuration Mode. The master is communicating with the Switch TAP Controller in the DS26900. Transparent Mode. The master is communicating directly with the selected secondary port. All pins are I/O in periphery JTAG mode except the TEST, TMREQ1, TMREQ2, EREQ, M1, M0, HIZ, RST, PTRST, PTCK, PTDI, PTDO, and PTMS pins. All outputs are rated at 8mA. Unused inputs must be tied to logic 1 or 0 if not used and a pullup/pulldown is not present. O = Output I = Input Ipu = Input with an internal pullup Ipd = Input with an internal pulldown P = Power

1. Functional Description The DS26900 is a star (radial) configur ation system-level JTAG signal multip lexer, which provides connectivity between a master port and secondary ports. The master po rt, which has been granted control of the switch, can also treat the unselected master ports as secondary ports. There are three possible master ports: ETM (External Test Master), TM1 (Test Master 1), and TM2 (Test Master 2). ETM functions as the primary master with TM1 and TM2 available as alternative masters. Direct arbitration determines which of the three possible masters can control the switch. ETM has the highest priority whenever there is a conflict over which master port can control the device. See Section 4.2 for more information on master port arbitration. JTAG connectivity is provided for up to 18 secondary ports per package as well as two additional secondary ports, TM1 and TM2, when they are not functioning as a master . Two DS26900s can be cascaded to provide additional secondary ports. The DS26900 can be in one of four modes: Single-Package Mode, Cascade-Master Mode, Cascade-Extension Mode, and Deselect Mode. The DS26900 contains two TAP controllers: one as part of the primary switch function and one to control the traditional JTAG interface at the periphery of the device for manufacturing test purposes. Configuration of the DS26900 is accomplished via the Switch TAP Controller. Configuration options include sensing the presence of secondary ports, addressing the target secondary port, reading/writing scratchpad registers, GPIO pin read/write, generating port resets, configuring path and signaling inversion options, and placing the DS26900 in transparent mode for direct communications with the secondary port. Communications with the DS26900 is accomplished via a master port while asserting the associated ports configure signal ( TRST1, TRST2, or ECFG) low. Connected ports (cards) are detected by sensing the port’s TMS pullup resistor, and the results are avail able in the Port Detection Register ( PDR). Selection of the desired port is accomplished by setting the address in t he Secondary Port Selection Register ( SPSR). Once the destination port selection bits are written, the Switch TAP Controller is returned to idle/r eset state and the configuration signal (TRST) is asserted high. The DS26900 routes the JTAG signal set (clock, data-in, data-out, mode select, and reset) from the arbitrated master to the sele cted destination port with controlled timing relationships. A reset for the secondary port can be generated by writing a register bi t after a port address is selected. Test masters can be swapped without affecting the logic state of the selected secondary port. The DS26900 also contains traditional boundary scan ci rcuitry at the periphery of the package for board manufacturing tests. See Section 9. This periphery boundary scan circuitry is independent and has priority over the operation of the master/slave multiplexer. It contains a se parate TAP controller with a 3-bit wide instruction code register. Signals associated with the periphery boundary scan circuitry are PTRST, PTMS, PTCK, PTDI, and PTDO. The DS26900 switch is designed to work at clock rates up to 50MHz. The arbitrated master is the source of the operating clock. However, the separate periphery JTAG function, as described above, operates at a maximum frequency of 10MHz.

1. Detailed Description

4.1 Modes of Operation

The mode pins, M1 and M0, provide four modes of operation as described in Table 4-1. Table 4-1. Mode Pins M1 M0 MODE OF OPERATION DESCRIPTION 0 0 Single-Package 18 secondary ports, TM1 and TM2 slave ports when configuration bit TM_SLAVE set to logic 1. 0 1 Cascade-Master First group of 18 secon dary ports, TM1 and TM2 are slave ports. 1 0 Cascade-Extension Second gr oup of 18 secondary ports. 1 1 Deselect Device is deselected (acts as if no master is present).

4.1.1 Single-Package Mode

Single-Package Mode allows access to 18 or 20 secondary ports. See Table 4-1 for M0 and M1 pin settings. If the TM_SLAVE bit in the DCR register is set = 0, the device is confi gured for three master ports and 18 secondary ports, as shown in Figure 4-1. If the TM_SLAVE bit in the DCR register is set = 1, the device is configured for one master port and 20 secondary ports, as shown in Figure 4-2. . In this configuration, TM1 and TM2 are used as secondary ports 19 and 20. If one or more master ports are unused, their REQ input pin(s) must be connected = VDD and the remaining unused inputs must be connected = VDD or VSS, but cannot be left floating. Figure 4-1. Configuration for 3 Masters, 18 Secondary Ports DS26900 ETM TM1 TM2 SECONDARY 1 SECONDARY 18 PREN M[1:0] = 00 VDD EXTERNAL TEST MASTER TEST MASTER 1 TEST MASTER 2 INSTRUCTION CODE = "0xxxx" Figure 4-2. Configuration for 1 Master, 20 Secondary Ports DS26900ETM SECONDARY 1 SECONDARY 18 PREN M[1:0] = 00 VDD EXTERNAL TEST MASTER INSTRUCTION CODE = "0xxxx" SCR.TM_SLAVE = 1 SECONDARY 19 SECONDARY 20

M[1:0] = 10 (EXTENSION) M[1:0] = 01 (MASTER) VDD EXTERNAL TEST MASTER TEST MASTER 1 TEST MASTER 2 ETM TM1 TM2 PREN SECONDARY 19 SECONDARY 36 DS26900 INSTRUCTION CODE = "0xxxx" INSTRUCTION CODE = "1xxxx"

4.1.2 Cascade Conf iguration Modes

The cascade configuration allows tw o devices to be connected together, the cascade master and the cascade extension device. This provides access to 36 secondary po rts plus the TM1 and TM2 port s (as slave ports) of the extension device without external co ntrol logic. The cascade master has its mode pins (M[1:0]) set = 01 and the cascade extension has its mode pins (M[1:0]) set = 10. See Table 4-1 for M0 and M1 pin settings. In Figure 4-3, secondary ports 1 to 18 or 19 to 36 are selected by the MSB of the instruction code. Each device has a 5-bit instruction register. The lower four LSBs have common definitions between the cascade devices, but the MSB of the 5-bit instruction register acts as an address bit. Instructions to be execut ed by the cascade master have their MSB set to 0. Instructions to be executed by the cascade extension have their MSB set to 1. The same instructions are loaded into each device, but only the appropriate dev ice (determined by the mode pin setting) executes the instruction. The PREN pin on the cascade master is connected = V DD to enable internal pullup/down resistors. On the cascade extension device, PREN is connected = VSS to disable internal pullup/down resistors. If one or more master ports are unused, their REQ input pin(s) must be connected = VDD and the remaining unused inputs must be connected = VDD or VSS, but cannot be left floating. Figure 4-3. Two Cascaded Devices

4.1.3 Deselect Mode and Redundancy

Deselect Mode allows multiple devices to be connected in parallel with the use of exte rnal logic controlling the M[1:0] and PREN pins. Deselect Mode is enabled when the mo de pins (M[1:0]) are both set high. This internally forces the TMREQ1, TMREQ2, and EREQ signals to go high, causing the DS26900 to act as though no active master is present. When both mode pins are set low via the external select logic, the device is selected and operated in Single-Package Mode. Applications requiring device redundan cy can be achieved by asserting PTRST low and HIZ low. This causes outputs to become high impedance and disables the pullups and pulldowns. During normal operation, PTRST is asserted low and HIZ is asserted high. A device that is deselected (M[1:0] = 11) internally acts as if an arbitrated master is not present. The Switch TAP Controller goes into Test-Logic-Reset (and the instruction register is clea red). The other programmable registers are left unchanged. Figure 4-4. Three Cascaded Devices Using External Select Logic DS26900 ETM TM1 TM2 SECONDARY 1 SECONDARY 18 PREN M[1:0] = 00/11 VDD EXTERNAL TEST MASTER TEST MASTER 1 TEST MASTER 2 ETM TM1 TM2 PREN SECONDARY 1 SECONDARY 18 DS26900 INSTRUCTION CODE = "0xxxx" INSTRUCTION CODE = "0xxxx" ETM TM1 TM2 PREN SECONDARY 1 SECONDARY 18 DS26900 INSTRUCTION CODE = "0xxxx" M[1:0] = 00/11 M[1:0] = 00/11 MODE SELECT LOGIC

4.2 Master Arbitration

The DS26900 can have one of three possible master ports: External Test Master (ETM), Test Master 1 (TM1), or Test Master 2 (TM2). The TM1 and TM2 ports can be bidi rectional based on the state of the configuration bit TM_SLAVE. An application, which has less than three masters, can use any combination of master ports. Table 4-2 lists the possible signal configurat ions and arbitrations for master. In the table, BLOCKED indicates that the JTAG signals are ignored both to and from this port, SLAVE indicates that this port is a target for the JTAG master, MASTER indicates the JTAG signal source port, CONFIG indicates the configuration mode for the DS26900, and NORMAL indicates normal JTAG signal operation from master to slave. Table 4-2. Master Arbitration EREQ ECFG TMREQ1 TRST1 TMREQ2 TRST2 ACTIVE MASTER MODE TM1 INTERFACE MODE TM2 INTERFACE MODE L L L X L X ETM CONFIG BLOCKED BLOCKED L H L X L X ETM NORMAL BLOCKED BLOCKED L H L X H X ETM NORMAL BLOCKED SLAVE L H H X L X ETM NORMAL SLAVE BLOCKED L H H X H X ETM NORMAL SLAVE SLAVE H X L L L X TM1 CONFIG MASTER BLOCKED H X L H L X TM1 NORMAL MASTER BLOCKED H X H X L L TM2 CONFIG SLAVE MASTER H X H X L H TM2 NORMAL SLAVE MASTER H X H X H X NONE INACTIVE SLAVE SLAVE Note: Slave mode of TM1 and TM2 is affected by the state of the configuration bit TM_SLAVE. L = Connect = VSS; H = Connect = VDD; X = Don’t care Only one master is allowed at any time. A test master that is in slave mode has the sense of all the JTAG signals reversed (outputs become inputs, inputs become outputs, and only TMREQ does not change), and it functions identically to a secondary port. A test master that is blocked ha s its control signals ignored (the JTAG outputs are blocked, JTAG inputs are set to a constant logic level, TMREQ is unaffected). Since the TM ports lack a separate configuration signal, TRST functions as the configuration signal. To avoid glitches on the output secondary ports, all the master signals (TMS, TDI, TDO, and CLK) should be set to logic 0 while switching the master to/from Test Master 1 or Test Master 2. The TM 1/TM2 slave interface mode will addition ally be affected by the state of the configuration bit TM_SLAVE. If an active master is not present ( EREQ, TMREQ1, and TMREQ2 are all logic 1), the Switch TAP Controller goes into Test-Logic-Reset and the content of the instruction register is cleared. A ll other registers retain their values. The MSB of the last instruction, before clearing, is always retained in a separate register unless global reset is asserted. The port whose address is in the Secondary Port Selection Register ( SPSR) is technically still selected, and that port will not be affected by the state of th e DPDV bit in the Device Configuration Register ( DCR). If a different master becomes the active master, communication s can resume with the port whose address is in the Secondary Port Selection Register and whose instruction r egister MSB is of the proper value. The Secondary Port Selection Register should be written with all zeros once communications with secondary ports is completed. A DS26900 in Deselect Mode disables detection of EREQ, TMREQ1, and TMREQ2, and the device therefore acts as if an active master is not present. Deselect Mode is selected when the mode pins (M[1:0]) are both asserted high.

The master grant signals, MGNT0, MGNT1, and MGNT2, are generated by the master arbitrator. These signals are available to the appropriate master to indicate that it has control. The MCI output is asserted low to indicate this possible conflict should more than one of the REQ signals be asserted low. An active signal indicates the active (selected) device by asserting ACT low. The ACT pin is asserted low under the conditions listed in Table 4-3. Table 4-3. ACT Output States M1 PIN M0 PIN INSTRUCTION REGISTER VALUE IS THERE AN ACTIVE MASTER? ACT OUTPUT 0 0 0XXXX Yes 0 0 0 1XXXX Yes 1 0 1 0XXXX Yes 0 0 1 1XXXX Yes 1 1 0 0XXXX Yes 1 1 0 1XXXX Yes 0 1 1 XXXXX X 1 X X XXXXX No 1 X = Don’t care

4.2.1 Missing Test Master or Unused Test Master Port

An unused or missing test master has its TMREQ signal tied high by the user (DS26900 has a pullup on that input pin so the user can leave this pin unconnected), which puts that port into slave mode.

4.2.2 Detection of the Presence of Secondary Ports

The presence of secondary ports is detected by sensi ng the logic level present on the STMSn signal (the STMSn signal on a port should have a pullup) on each secondary port and test master port. Logic 1 is latched into the 20-bit Port Detection Register (PDR) for each pullup that is sensed. The STMSn and TMSn signals are sensed and the Port Detection Register ( PDR) is updated each time the Switch TAP Controller passes out of the reset state. (TMSn signals can only be sensed on TM1/TM2 slave-mode ports.)

4.2.3 Selection of the Secondary Port

Selection of the secondary port (“slav e”) is accomplished by writing a 5-bit address into the Secondary Port Selection Register (SPSR). Due to the star configuration, only one port can be selected at a time. Ports that are not detected as being present by sensing the pullup on t he secondary port’s TMS pin can still be selected, and the signals will be sent to that port. This 5-bit secondary port selection address is complemented and used to generate the selected slave port indicator bits (SSPI[4:0]). These bits can be used as a visual indicator as to which slave port has been selected. Once communications with a secondary port has been completed, the Secondary Port Selection Register ( SPSR) should be set to all zeros. If not, the selected port add ress will not respond to the DPDV bit of the Device Configuration Register (DCR). This is true if an active master is present or not.

4.2.4 Master Port/Secondary Port Path Timing Description

Each of the arbitrated masters passes into a 3 x 1 multip lexer and then a 1 x 20 multiplexer, such that any of the three possible masters can connect to any of the 20 possi ble secondary ports (18 secondary ports plus the test master ports when available). The test clock (TCK), test mode select (TMS), test data in (TDI), and test data out

(TDO) signals can each be individually inve rted by setting an optional configuration bit. Figure 1-1 diagrams this path in a simple form.

4.3 GPIO Pins—General-Purpose I/O

The general-purpose I/O (GPIO) are bidirectional pins that offer the user the ability to output logic levels or read input logic levels. Each GPIO pin can be configured to output logic 1, logic 0, or to be an input. Configuration of the GPIO pins for write or read operation is accomplished by writing the GPIO Confi guration and Write Register (GPIOCR) bits. The reading the logic state of the GP IO pins can be accomplished by acce ssing the 4-bit GPIO Read Register (GPIORR). Pins that are configured for read mode read the input logic state in the register. Pins that are configured for output mode read back the logic state for which those pins are configured.

4.4 Programmable Pullup/Pulldown Resistors

A hardware configuration pin (PREN) is provided to enabl e/disable pull resistors on the input signal pins of the three masters. PREN works such that when connected to VDD, the following signals have pull resistors enabled: TCK1, TCK2, ETDI, ETCK, TMS1, TMS2—20k Ω pulldown TDI1, TDI2, ETDO, TDO1, TDO2—10k Ω pullup TRST1, TRST2, ECFG, ETMS—10k Ω pullup When connected to V SS, the pull resistors on the signals above are disabled. PREN can be connected to V DD for single device implementations or for one of the devices in a multiple-device implementation. Connecting PREN to VDD on multiple devices, which are in parallel, would cause the pull resistors to be connected in parallel. This would have the undesirable effect of halving the pull-resistor values.

4.5 Signal Path Configuration—Inversions

To help overcome possible timing issues, the JTAG signal path timing can be modified in limited ways in the Device Configuration Register ( DCR). Signal path timing changes are global and, once set, they apply to all secondary ports until reconfigured. Figure 1-1 diagrams the relative placement of the signal path modifier logic. There are several possible options:

• The test clock (TCK) from the arbitrated master to a slave port can be inverted by setting the TCKi bit.
• The test data from the arbitrated master to a slave port can be inverted by setting the TDIi bit.
• The test data coming from the slave port to the arbitrated master can be inverted by setting the TDOi bit.
• The TMS signal from the arbitrated master to a slave port can be inverted by setting the TMSi bit. There is only one set of configuration bits. Switching from port to port does not change the configuration bits.

4.6 Switch Configuration by External Test Master

The External Test Master (ETM) has the highest priori ty in the master arbitrat ion circuit, so asserting EREQ low makes the ETM the master. The ETM accesses the configuration mode of the switch by asserting EREQ low and ECFG low. Access is then provided to the Switch TAP Controller. While in configuration mode, the secondary slave ports’ JTAG signals are asserted low (except STRSTn signals, which are high) and do not toggle. In configuration mode, the master has access to the configuratio n registers in the Swit ch TAP Controller. When EREQ is asserted low and a Secondary Port Selection Register (SPSR) address from 1 to 18 is selected, the selected secondary port JTAG signal group follows the ETM signals. The Switch TAP Controller operates as an IEEE 1149.1 TAP controller. Instruct ions can be written and registers written or read using the 1149.1 state diagram. The Switch TAP Controller uses the inverted ECFG signal as reset.

It can also be reset by asserting ETMS high for at leas t six clock cycles. The Switch TAP Controller should be returned to the Test-Logic-Reset or Run-Test/Idle state before asserting ECFG high. To communicate with a particular secondary port, an address from 1 to 18 must be written into the 5-bit Secondary Port Selection Register ( SPSR) during the configuration mode. This address does not change unless it is overwritten. However, toggling global rest (RST) sets the Secondary Port Selection Register (SPSR) to 00000b. An address of 00000b in the Secondary Port Selection Register ( SPSR) (or any nonvalid port address) blocks communications to all slave ports. Only one secondary port can be selected at a time.

4.7 Switch Configuration by Test Master 1 or Test Master 2

The master arbitration circuit determines which test mast er has priority. Test Master 1 (TM1) or Test Master 2 (TM2) configures the sw itch by asserting its TMREQn low and TRSTn low. Access to the switch’s configuration mode is accomplished by asserting TRSTn low. While in configuration mode, the secondary slave ports’ JTAG signals are asserted low (except STRSTn signals, which are high) and do not toggle. In configuration mode, the master has access to the confi guration registers in the Switch TAP Controller in the DS26900. When TREQn is asserted low and a Secondary Port Selection Register ( SPSR) address from 1 to 18 (34) is selected, the secondary port JTAG signal group toggl es normally and the arbitrated test master acts as the master. The Switch TAP Controller ope rates as a IEEE 1149.1 TAP controller. In structions can be written and registers written or read using the 1149.1 state diagram. The Switch TAP Controller uses the inverted TRSTn signal as reset. It can also be reset by asserting TMSn high for at leas t six clock cycles. The Switch TAP Controller should be returned to the Test-Logic-Reset or Run-Test/Idle state before asserting TRSTn high. To communicate with a particular secondary port, an address from 1 to 18 must be written into the 5-bit Secondary Port Selection Register ( SPSR) during the configuration mode. This address does not change unless it is overwritten. However, toggling global rest (RST) sets the Secondary Port Selection Register (SPSR) to 00000b. An address of 00000b in the Secondary Port Selection Register ( SPSR) (or any nonvalid port address) blocks communications to all slave ports. Only one secondary port can be selected at any time.

1. Resets

5.1 Global Reset Usage

The global reset, RST pin, does not affect the state machine logic of the Switch TAP Controller. The RST pin resets all other read and/or write registers.

5.2 Secondary Port Resets

The reset pins for secondary ports are always logic 1 unless the PORT_RST or the ALL_PORTS_RST instruction is set in configuration mode. When the PORT_RST instruction is loaded, the valid ports STRSTn is asserted logic 0 for three master TCLKs before returning to logic 1. Wh en the ALL_PORTS_RST instruction is loaded, all valid STRSTn signals are asserted logic 0 for three master TCLKs bef ore returning to logic 1. When not in configuration mode, the secondary ports STRSTn signals are always logic 1.

1. Configuration Mode Configuration mode is used by a master to program t he options in the DS26900 switch and to configure the address of the secondary port. Configurati on mode for the ETM is accomplished when EREQ and ECFG are both asserted low. While EREQ and ECFG are asserted low, the secondary slave ports JTAG signals are not allowed to toggle (STRSTn can only be asserted low by the Sw itch TAP Controller port reset instructions). In configuration mode, the master has access to the configuration TAP controller in the DS26900. When EREQ is asserted low and ECFG is asserted high, the JTAG signal group toggles normally and the ETM acts as the master. Configuration mode for the Test Master 1 and Test Master 2 is accomplished when TREQn and TRSTn are both asserted low. While TMREQ and TRSTn are both asserted low, the JTAG signal group remains static. In configuration mode, the master has access to the configur ation TAP controller in the DS26900. To set the target (slave) port, the port address must be written to the Secondary Port Selection Register (SPSR). There is only one configuration mode for the DS26900. As a result, the master can set a configuration that remains valid for any master secondary port until reconfigured or RST is asserted low.

6.1 Switch TAP Controller

The Switch TAP Controller is implemented as standard IEEE 1149.1 TAP co ntroller. See Section 9.2 and Figure 9-2.

6.1.1 Switch Instructions

Table 6-1. Switch TAP Instruction Codes INSTRUCTIONS SELECTED REGISTER SINGLE-PACKAGE AND CASCADE MASTER INSTRUCTION CODES CASCADE EXTENSION INSTRUCTION CODES IDCODE ID Register ( IDR) 00000 10000 PORT_DET Port Detection Register ( PDR) 00001 10001 PORT_SEL Secondary Port Selection Register (SPSR) 00010 10010 GPIO_CFG GPIO Configuration and Write Register ( GPIOCR) 00011 10011 GPIO_READ GPIO Read Register ( GPIORR) 00100 10100 CONFIG Device Configuration Register DCR) 00101 10101 SCRATCH_1 Scratchpad 1 Register ( SPR1) 00110 10110 SCRATCH_2 Scratchpad 2 Register ( SPR2) 00111 10111 PORT_RST Port Reset for a Selected Port 01000 11000 NOP No Operation 01001–01110 11001–11110 ALL_PORTS_RST Global Port Test Reset 01111 11111 When performing a register write, the cu rrent value of a register is shifted out while the new register value is being shifted in. For read-only registers, some bit value must be shifted in (which is ignored) to shift out the current register value.

The MSB of the instruction code acts as an address bit. When in cascade configuration, the cascade master’s TDO output and port communications is enabled only when the in struction MSB is 0. The cascade extension’s TDO output and port communications is enabled only when the instruction MSB is 1. In Single-Package Mode, TDO output and port communications is enabled only when the instruction MSB is 0.

6.1.1.1 IDCODE

The IDCODE instruction allows access to the ID Register ( IDR). The IDR register is an 8-bit read-only register that contains the revision code for the DS26900 in the lower 4 bi ts and a fixed 4-bit code in the upper 4 bits. This is identical to the revision code of the ID code, wh ich is used for the periphery boundary scan. The IDR register is read-only. Writes to this register are ignored.

6.1.1.2 PORT_DET

The PORT_DET instruction initiates the sensing of the presence of secondary ports and allows access to the 20-bit Port Detection Register ( PDR). The process of port detection tempor arily changes the STMSn bidirectional pin outputs to inputs, senses which ports read as logical 1 (ports should have a 10k Ω resistive pullup on their STMSn pin and the DS26900 has a 20k Ω pulldown), and saves the results to the PDR register. Then the user must wait in the Run-Test-Idle state for a period of time to allow the vo ltage on the STMS pin to settle, typically 100ms. A “1” in a bit position indicates that logic 1 was sensed on that port’s STMS pin. However, due to implementation variables, logic 0 in a bit position does not necessarily imply that a device is not attached to that port (the port STMS pin must have a pullup on STMS in order to be sensed). The PDR register inputs are level sensitive and are sampled after the PORT_DET instruction is loaded. The values in this register do not affect the operation of the DS26900. Port detection works for single-package and the two-package cascade configuration. Writes to this register are ignored.

6.1.1.3 PORT_SEL

The PORT_SEL instruction allows access to the 5-bi t read/write Secondary Port Selection Register ( SPSR). Writing a value to this register selects a port with wh ich to communicate. Valid addresses are from 00001b (port one selected) to 10100b (TMS2). Addresses greater than 10100b and address 00000b do not select a port. Selecting an empty or nonexistent port has no adverse effect on the device, and no secondary port signals will toggle.

6.1.1.4 GPIO_CFG

The GPIO_CFG instruction allows access to the 8-bit read/write GPIO Configuration and Write Register (GPIOCR). The four GPIO pins can be individually configured to be an input, output logic 1, or output logic 0. The values, which are sensed on the pins, are available in the GPIO Read Register (GPIORR) via the GPIO_READ instruction. After global reset, the GPIO Configuration and Write Register ( GPIOCR) bits are set to 00000000b and the GPIO pins are set to input mode.

6.1.1.5 GPIO_READ

The GPIO_READ instruction allows access to the 4-bit read-only GPIO Read Register ( GPIORR). A “1” in a bit position indicates that logic 1 was sensed on that input’s GPIO pin, and a “0” in a bit position indicates that logic 0 was sensed on that GPIO pin. If a pin was configured as an output, the register bit indicates the value being output. Writes to this register are ignored. The GPIO inputs are level sensitive and are sampled after the GPIO_READ instruction is loaded. GPIO pins that are configured as outputs are always read in this register as the value that is being output. After reset, the GPIO Read Register (GPIORR) bits are set to 0000b until a GPIO_READ instruct ion is given. Writes to this register are ignored.

6.1.1.6 CONFIG

The CONFIG instruction allows access to the 6- bit read/write Device Configuration Register ( DCR). The DCR register controls options such as path and signaling inversions and the default deselected port drive values.

6.1.1.7 SCRATCH_1

The SCRATCH_1 instruction allows access to the 32-bit read/write Scratchpad 1 Register ( SPR1). The SPR1 register is a user storage location, which is reset by the global reset signal. The values stored in this register do not affect the operation of the DS26900.

6.1.1.8 SCRATCH_2

The SCRATCH_2 instruction allows access to the 32-bit read/write Scratchpad 2 Register ( SPR2). The SPR2 register is a user storage location, which is reset by the global reset signal. The values stored in this register do not affect the operation of the DS26900.

6.1.1.9 PORT_RST

The PORT_RST instruction generates a port-specific STRSTn signal. Port selection must first be performed by loading an address into the Secondary Port Selection Register ( SPSR). The selected STRSTn signal is asserted high, asserted low for three (TCLK) clock periods, and then is asserted high. If the SPSR register contains 00000b or an invalid address, no port reset is generated. The three-clock-period width is a fixed value. Exit from configuration mode before three clock periods have elapsed can shorten the width of this pulse.

6.1.1.10 NOP

The NOP instruction is “no operation.” It does not perform a function. 6.1.1.11ALL_PORTS_RST The ALL_PORTS_RST instruction generates a STRSTn signal to all possible 18 (or 20) ports simultaneously. All STRSTn signals start by being asserted high, asserted low for three (TCLK) clock periods, and then asserted high. The three-clock-period width is a fixed value. Exit from configuration mode before three clock periods have elapsed can shorten the width of this pulse.

1. Device Registers Table 7-1. DS26900 List of Registers REGISTER NAME SIZE (BITS) FUNCTION IDR 8 Device Identification and Revision Code Register DCR 6 Device Configuration Register GPIOCR 8 GPIO Configuration and Write Register GPIORR 4 GPIO Read Register PDR 20 Port Detection Register SPSR 5 Secondary Port Selection Register SPR1 32 Scratchpad Register 1 SPR2 32 Scratchpad Register 2 Register Name: IDR Register Description: 8-Bit Device Identification and Revision Code Register Bit # 7 6 5 4 3 2 1 0 Name ID7 ID6 ID5 ID4 ID3 ID2 ID1 ID0 Reset 1 1 0 0 Revid[3] Revi d[2] Revid[1] Revid[0] Bits 7 to 4: (ID[7:4]) Fixed binary pattern. Bits 3 to 0: (ID[3:0]). Bit revision ID.

Register Name: DCR Register Description: 6-Bit Device Configuration Register Bit # 7 6 5 4 3 2 1 0 Name — — TM_SLAVE DPDV TMSi TDIi TDOi TCKi Reset — — 0 0 0 0 0 0 Bit 5: Test Master Slave Enable (TM_SLAVE). Determines in conjunction with M[1:0] if the DS26900 device will drive nonmaster TM1/TM2 as slaves. If the TM buses ar e in parallel with more than one DS26900, only one DS26900 can drive TM1/TM2 as a slave. The following table describes the combinations. MODE M[1:0] TM_SLAVE BIT TM1/TM2 SLAVE CAPABLE Single-Package 00 0 No Single-Package 00 1 Yes Cascade Master 01 N/A Yes Cascade Extension 10 N/A No Deselect 11 N/A N/A Bit 4: Deselected Port Drive Values (DPDV). This bit determines the logic levels driving a deselected secondary port according to the following table. Note: This configuration bit does not apply to TM1 or TM2 in slave mode. TM1 or TM2 port signals in slave mode will never be high impedance. A secondary port is not selected (deselected) when device is in switch configuration mode, or when the particular port address is not loaded in the Se condary Port Selection Register (SPSR). The state of this bit can be monitored via the DPDV pin. SIGNAL DPDV = 0 DPDV = 1 STMSn 0 HiZ * STRSTn 1 1 STDIn 0 HiZ * STCKn 0 0 *HiZ is a high-impedance state with no internal pullup/down resistors active. Bit 3: Test Mode Select Invert (TMSi). Invert the TMS signal from the arbitrated master to the selected slave port by setting this bit to logic 1. Bit 2: Test Data In Invert (TDIi). Invert the TDI signal from the arbitrated master to the selected slave port by setting this bit to logic 1. Bit 1: Test Data Out Invert (TDOi). Invert the TDO signal from the selected sl ave port to the arbitrated master by setting this bit to logic 1. Bit 0: Test Clock Invert (TCKi). Invert the TCK from the arbitrated master to the selected slave port by setting this bit to logic 1.

Register Name: GPIOCR Register Description: 8-Bit GPIO Configuration and Write Register Bit # 7 6 5 4 3 2 1 0 Name GPIO3[1] GPIO3[0] GPIO2[1] GPIO2[0] GPIO1[1] GPIO1[0] GPIO0[1] GPIO0[0] Reset 0 0 0 0 0 0 0 0 Bit 7: GPIO3 Configuration Bit 1 (GPIO3[1]) GPIOn[1] GPIOn[0] GPIOn PIN MODE 0 0 Input 0 1 Output logic 0 1 0 Output logic 1 1 1 Reserved Bit 6: GPIO3 Configuration Bit 0 (GPIO3[0]) Bit 5: GPIO2 Configuration Bit 1 (GPIO2[1]) Bit 4: GPIO2 Configuration Bit 0 (GPIO2[0]) Bit 3: GPIO1 Configuration Bit 1 (GPIO1[1]) Bit 2: GPIO1 Configuration Bit 0 (GPIO1[0]) Bit 1: GPIO0 Configuration Bit 1 (GPIO0[1]) Bit 0: GPIO0 Configuration Bit 0 (GPIO0[0]) Register Name: GPIORR Register Description: 4-Bit GPIO Read Register Bit # 7 6 5 4 3 2 1 0 Name — — — — IN[3] IN[2] IN[1] IN[0] Reset — — — — 0 0 0 0 Bit 3: GPIO3 Input Value (IN[3]) Bit 2: GPIO2 Input Value (IN[2]) Bit 1: GPIO1 Input Value (IN[1]) Bit 0: GPIO0 Input Value (IN[0])

Register Name: PDR Register Description: 20-Bit Port Detection Register (Read-Only) Bit # 23 22 21 20 19 18 17 16 Name — — — — PORT20 (TM2 SLAVE) PORT19 (TM1 SLAVE) PORT18 PORT17 Reset — — — — 0 0 0 0 Bit # 15 14 13 12 11 10 9 8 Name PORT16 PORT15 PORT14 PORT13 PORT12 PORT11 PORT10 PORT9 Reset 0 0 0 0 0 0 0 0 Bit # 7 6 5 4 3 2 1 0 Name PORT8 PORT 7 PORT6 PORT5 PORT4 PORT3 PORT2 PORT1 Reset 0 0 0 0 0 0 0 0 Bits 19 and 18: Port Detection (PORT[20:19]). If the TMS signal on PORTn has a 10kΩ pullup resistor, a value of 1 is recorded in the bit location corresponding to PORTn. The Switch TAP Cont roller instruct ion PORT_DET instruction triggers the port detection action. Detection is also determined by the settings of the M[1:0] pins and the TM_SLAVE configuration bit. Bits 17 to 0: Port Detection (PORT[18:1]). If the TMS signal on PORTn has a 10kΩ pullup resistor, a value of 1 is recorded in the bit location corresponding to PORTn. The Switch TAP Controller instruction PORT_DET instruction triggers the port detection action.

Register Name: SPSR Register Description: 5-Bit Secondary Port Selection Register Bit # 7 6 5 4 3 2 1 0 Name — — — SSP[4] SSP[3] SSP[2] SSP[1] SSP[0] Reset — — — 0 0 0 0 0 Bits 4 to 0: Secondary Port Selection (SSP[4:0]). Port address (see Table 7-2). Table 7-2. Secondary Port Selection Bits and Indicator Pins SSP[4:0] BITS SELECTED PORT SSPI[4:0] PINS

00000 No Port Selected 11111

00001 Port 1 11110

00010 Port 2 11101

00011 Port 3 11100

00100 Port 4 11011

00101 Port 5 11010

00110 Port 6 11001

00111 Port 7 11000

01000 Port 8 10111

01001 Port 9 10110

01010 Port 10 10101

01011 Port 11 10100

01100 Port 12 10011

01101 Port 13 10010

01110 Port 14 10001

01111 Port 15 10000

10000 Port 16 01111

10001 Port 17 01110

10010 Port 18 01101

10011 Port 19*

(TM1 Slave Mode) 01100

10100 Port 20*

(TM2 Slave Mode) 01011 10101–11111 No Port Selected 11111 *Ports 19 and 20 are only available if TM1 and/or TM2 are available to be driven in slave mode.

Register Name: SPR1 Register Description: 32-Bit Scratchpad Register 1 Bit # 31 30 29 28 27 26 25 24 Name SR1[31] SR1[30] SR1[29] SR1[28] SR1[27] SR1[26] SR1[25] SR1[24] Reset 0 0 0 0 0 0 0 0 Bit # 23 22 21 20 19 18 17 16 Name SR1[23] SR1[22] SR1[21] SR1[20] SR1[19] SR1[18] SR1[17] SR1[16] Reset 0 0 0 0 0 0 0 0 Bit # 15 14 13 12 11 10 9 8 Name SR1[15] SR1[14] SR1[13] SR1[12] SR1[11] SR1[10] SR1[9] SR1[8] Reset 0 0 0 0 0 0 0 0 Bit # 7 6 5 4 3 2 1 0 Name SR1[7] SR1[6] SR1[5] SR1[4] SR1[3] SR1[2] SR1[1] SR1[0] Reset 0 0 0 0 0 0 0 0 Bits 31 to 0: Scratchpad Register 1 Bits 31 to 0 (SR1[31:0]) Register Name: SPR2 Register Description: 32-Bit Scratchpad Register 2 Bit # 31 30 29 28 27 26 25 24 Name SR2[31] SR2[30] SR2[29] SR2[28] SR2[27] SR2[26] SR2[25] SR2[24] Bit # 23 22 21 20 19 18 17 16 Name SR2[23] SR2[22] SR2[21] SR2[20] SR2[19] SR2[18] SR2[17] SR2[16] Bit # 15 14 13 12 11 10 9 8 Name SR2[15] SR2[14] SR2[13] SR2[12] SR2[11] SR2[10] SR2[9] SR2[8] Bit # 7 6 5 4 3 2 1 0 Name SR2[7] SR2[6] SR2[5] SR2[4] SR2[3] SR2[2] SR2[1] SR2[0] Bits 31 to 0: Scratchpad Register 2 Bits 31 to 0 (SR2[31:0])

1. Additional Application Information

8.1 Accessing Individual Device JTAG on a Board

The DS26900 can be used to provide access to individual device JTAG chains on a board. For this configuration, TMREQ1 and TMREQ2 are tied high and EREQ is tied low, yielding a single-master configuration with a 5-pin interface. Individual subports on the DS26900 can be selected in configuration mode.

8.2 Using LED Indicators on the SSPI, ACT and MCI Pins

LED indicators can be attached to the MCI, ACT, and/or SSPI[4:0] pins by connecting the anode of the LED to V DD via a series resistor and the cathode connected to the appropriate DS26900 pin. Series resistance should be no less than approximately 175Ω to limit current to 8mA. 8.3 Using 2.7V and 1.8V Logic Levels with the DS26900 The DS26900 operates at a nominal s upply voltage of 3.3V. The input buffers are designed to switch at midrail (VDD/2 = ~1.65V) with some hysteresis. This allows the input buffers the ability to sense 2.7V and 1.8V CMOS logic levels without modification or configuration in some applications. With that in mind, compatibility with 2.7V and 1.8V CMOS logic levels (other than 3.3V CMOS logic level) is not expressly guaranteed. The output buffers are capable of 3.3V CMOS (rail-to-rail) logic levels.

8.4 Series Termination Resistors

Although not part of the IEEE 1149.1 specification, some PCB designs require series termination of clock signals at the electrical source. For the DS26900, the recommended typical series termination value for outputs is 33Ω. This value can vary depending on the PCB’s trace geometries.

1. Periphery JTAG

9.1 Periphery JTAG Description

The DS26900 contains traditional boundary scan circuitry at the periphery of the package for board manufacturing tests. This periphery boundary scan circuitry is independent and has priority over the operation of the master/slave multiplexer. It contains a separate TAP controller with a 3-bit wide instruction code register. Signals associated with the periphery boundary scan circuitry are PTRST, PTMS, PTCK, PTDI, and PTDO. The DS26900 supports t he standard instruction codes SAMPLE/PRELOAD, BYPASS, and EXTEST. Optional public instructions included are HIGHZ, CLAMP and IDCODE. See Figure 9-1 for a block diagram. The DS26900 contains the following items, which meet the requirements set by the IEEE 1149.1 Standard Test Access Port and Boundary Scan Architecture: Test Access Port (TAP) TAP Controller Instruction Register Bypass Register Boundary Scan Register Device Identification Register Details on the Boundary Scan Arch itecture and the Test Access Po rt can be found in IEEE 1149.1-2001, IEEE 1149.1-1990, IEEE 1149.1a-1993, and IEEE 1149.1b-1994. Figure 9-1. Periphery JTAG Block Diagram BOUNDARY SCAN REGISTER IDENTIFICATION REGISTER BYPASS REGISTER INSTRUCTION REGISTER TEST ACCESS PORT CONTROLLER MUX SELECT TRI-STATE PTDI 10kΩ PTMS 10kΩ PTCLK PTRST 10kΩ PTDO

9.2 JTAG TAP Controller State Machine Description

This section covers the details on the operation of the Test Access Port (TAP) Cont roller State Machine. See Figure 9-2 for details on each of the states described. The TAP controller is a finite state machine that responds to the logic level at PTMS on the rising edge of PTCLK. Figure 9-2. JTAG TAP Controller State Machine Test-Logic-Reset. Upon device power-up, the TAP c ontroller starts in the Test-Logi c-Reset state. The instruction register contains the IDCODE instruction. All system logic on the device operates normally. Run-Test-Idle. Run-Test-Idle is used between scan operations or during specific tests. The instruction register and test register remain idle. Select-DR-Scan. All test registers retain their pr evious state. With PTMS low, a rising edge of PTCLK moves the controller into the Capture-DR state and initiates a scan sequence. PTMS high moves the controller to the Select- IR-SCAN state. Capture-DR. Data can be parallel loaded into the test data regi sters selected by the cu rrent instruction. If the instruction does not call for a parallel load or the selected register does not allow parallel loads, the test register Test-Logic-Reset Run-Test/Idle Select DR-Scan Capture-DR Shift-DR Exit1- DR 1 Pause-DR Exit2-DR Update-DR Select IR-Scan Capture-IR Shift-IR Exit1-IR 1 Pause-IR Exit2-IR Update-IR

remains at its current value. On the rising edge of PTCLK, the controller goes to the Shift-DR state if PTMS is low or it to the Exit1-DR state if PTMS is high. Shift-DR. The test data register selected by the current instruction is c onnected between PTDI and PTDO and shifts data one stage towards its serial output on each ri sing edge of PTCLK. If a test register selected by the current instruction is not placed in the serial path, it maintains its previous state. Exit1-DR. While in this state, a rising edge on PTCLK with PT MS high puts the controller in the Update-DR state, which terminates the scanning process. A rising edge on PTCLK with PTMS low puts the controller in the Pause- DR state. Pause-DR. Shifting of the test registers is halted while in this state. All test register s selected by the current instruction retain their previ ous state. The controller remains in this state while PTMS is low. A rising edge on PTCLK with PTMS high puts the controller in the Exit2-DR state. Exit2-DR. While in this state, a rising edge on PTCLK with PTMS high puts the controller in the Update-DR state and terminates the scanning process. A rising edge on PTCLK with PTMS low puts the controller in the Shift-DR state. Update-DR. A falling edge on PTCLK while in the Update-DR state latches the data from the shift register path of the Test registers into the data output latches. This prevents changes at the parallel output due to changes in the shift register. A rising edge on PTCLK with PTMS low puts the controller in the Run-Test-Idle state. With PTMS high, the controller enters the Select-DR-Scan state. Select-IR-Scan. All test registers retain their previous state. The instruction register remains unchanged during this state. With PTMS low, a rising edge on PTCLK moves the cont roller into the Capture-IR state and initiates a scan sequence for the Instruction register. PTMS high duri ng a rising edge on PTCLK puts the controller back into the Test-Logic-Reset state. Capture-IR. The Capture-IR state is used to load the shift register in the Instruction register with a fixed value. This value is loaded on the rising edge of PTCLK. If PTMS is high on the rising edge of PTCLK, the controller enters the Exit1-IR state. If PTMS is low on the rising edge of PTCLK, the controller enters the Shift-IR state. Shift-IR. In this state, the shift register in the instruction register is connected between PTDI and PTDO and shifts data one stage for every rising edge of PTCLK towards the serial output. The parallel register, as well as all test registers, remains at its previous states. A rising edge on PTCLK with PTMS high moves the controller to the Exit1- IR state. A rising edge on PTCLK with PTMS low keeps t he controller in the Shift-IR state while moving data one stage through the Instruction shift register. Exit1-IR. A rising edge on PTCLK with PTMS low puts the controll er in the Pause-IR state. If PTMS is high on the rising edge of PTCLK, the controller enters the Update-IR state and terminates the scanning process. Pause-IR. Shifting of the Instruction register is halted te mporarily. With PTMS high, a rising edge on PTCLK puts the controller in the Exit2-IR state. The controller remains in the Pause-IR state if PTMS is low during a rising edge on PTCLK. Exit2-IR. A rising edge on PTCLK with PTMS high put the controll er in the Update-IR state. The controller loops back to the Shift-IR state if PTMS is low during a rising edge of PTCLK in this state. Update-IR. The instruction shifted into the instruction shift r egister is latched into the parallel output on the falling edge of PTCLK as the controller enters this state. Once latc hed, this instruction becomes the current instruction. A rising edge on PTCLK with PTMS low, puts the controller in the Run-Test-Idle state. With PTMS high, the controller enters the Select-DR-Scan state.

9.3 JTAG Instruction Register and Instructions

The instruction register contains a shift register as well as a latched parallel output and is 3 bits in length. When the TAP controller enters the Shift-IR state, the instruction sh ift register is connected between PTDI and PTDO. While in the Shift-IR state, a rising edge on PTCLK with PTMS low shifts data one stage towards the serial output at PTDO. A rising edge on PTCLK in the Exit1-IR state or the Exit2-IR state with PTMS high moves the controller to the Update-IR state. The falling edge of that same PTCLK latches the data in the instruction shift register to the instruction parallel output. Instructions supported by the DS26900 and their respective operational binary codes are shown in Table 9-1. Table 9-1. Periphery JTAG Instruction Codes INSTRUCTIONS SELECTED REGI STER INSTRUCTION CODES SAMPLE/PRELOAD Boundary Scan 010 BYPASS Bypass 111 EXTEST Boundary Scan 000 CLAMP Bypass 011 HIGHZ Bypass 100 IDCODE Device Identification 001

9.3.1 SAMPLE/PRELOAD

This is a mandatory instruction for th e IEEE 1149.1 specification. This in struction supports two functions. The digital I/Os of the device can be sampled at the boundary scan register without interfering with the normal operation of the device by using the Capture-DR state. SAMPLE/PRELOAD also allows the DS26900 to shift data into the boundary scan register via PTDI using the Shift-DR state.

9.3.2 EXTEST

EXTEST allows testing of all interconnections to the device. When the EXTEST instruction is latched in the instruction register, the following actions occur. Once en abled via the Update-IR state, the parallel outputs of all digital output pins are driven. The boundary scan register is connected between PTDI and PTDO. The Capture-DR samples all digital inputs into the boundary scan register.

9.3.3 BYPASS

When the BYPASS instruction is latched into the parallel Instruction register , PTDI connects to PTDO through the 1-bit bypass test register. This allows data to pass from PTDI to PTDO not affecting the device's normal operation.

9.3.4 IDCODE

When the IDCODE instruction is latched into the parallel Instruction register, the iden tification test register is selected. The device identification code is loaded into the Identification register on the rising edge of PTCLK following entry into the Capture-DR stat e. Shift-DR can be used to shift the identification code out serially via PTDO. During Test-Logic-Reset, the identification code is forc ed into the instruction register's parallel output. The device ID code always has a one in the LSB position. T he next 11 bits identify the manufacturer's JEDEC number and number of continuation bytes followed by 16 bits for t he device and 4 bits for the version. The device ID code for the DS26900 is 0008D143.

9.3.5 HIGHZ

All digital outputs are placed into a hi gh-impedance state. The bypass regist er is connected between PTDI and PTDO.

9.3.6 CLAMP

All digital outputs pins output data from the boundary sc an parallel output while connecting the bypass register between PTDI and PTDO. The outputs do not change during the CLAMP instruction.

9.4 JTAG Test Registers

IEEE 1149.1 requires a minimum of two te st registers: the bypass register and the boundary scan register. An optional test register has been included in the device design. This test register is the identification register, and is used in conjunction with the IDCODE instruction and the Test-Logic-Reset state of the TAP controller.

9.4.1 Bypass Register

This is a single 1-bit shift register used in conjunct ion with the BYPASS, CLAMP, and HIGHZ instructions, which provides a short path between PTDI and PTDO.

9.4.2 Identification Register

The Identification register contains a 32-bit shift regi ster and a 32-bit latched parallel output. This register is selected during the IDCODE instruction and when the TAP controller is in the Test-Logic-Reset state.

9.4.3 Boundary Scan Register

This register contains both a shift regi ster path and a latched parallel output for all control cells and digital I/O cells and is 361 bits in length.

1. Operating Parameters ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Lead with Respect to VSS (except VDD) ……………………………………………..-0.3V to 5.5V This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

10.1 Thermal Information

Table 10-1. Thermal Characteristics PARAMETER VALUE Target Ambient Temperature Range -40°C to +85°C Die Junction Temperature Range -40°C to +126°C Theta-JC (Junction to Top of Case) 10°C/W Theta-JB (Junction to Bottom Pins) 10°C/W Theta-JA, Still Air 22°C/W (Note 1)

100 LFM 20°C/W (Note 1)

200 LFM 17°C/W (Note 1) Theta-JA

500 LFM 15°C/W (Note 1)

Note 1: Theta-JA values are estimates using JEDEC-standard PCB and enclosure dimensions.

10.2 DC Characteristics

Table 10-2. Recommended DC Operating Conditions (TA = -40°C to +85°C) PARAMETER SYMBOL MIN TYP MAX UNITS Logic 1 V IH 2.4 4.2 V Logic 0 V IL -0.3 0.8 V Supply (VDD) V DD 3.135 3.465 V Table 10-3. DC Electrical Characteristics (VDD = 3.3V ±5%, TA = -40°C to +85°C.) PARAMETER SYMBOL MIN TYP MAX UNITS Supply Current (VDD = 3.465V) I DD 15 mA Lead Capacitance C IO 7 pF Input Leakage I IL -10 +10 μA Input Pins with Internal Pullup Resistors I ILP -250 +10 μA Output Current (2.4V) I OH -4.0 mA Output Voltage (IOH = -4.0mA) V OH 2.4 V Output Voltage (IOH = +4.0mA) V OL 0.4 V Output Current (0.4V) I OL +4.0 mA

1. AC Timing Unless otherwise noted, all timing numbers assume 20pF test load on output signals, 40pF test load on bus signals.

11.1 Switch TAP Controller Interface Timing

Table 11-1. Switch TAP Controller Interface Timing (VDD = 3.3V ±5%, TA = -40°C to +85°C.) (See Figure 11-1.) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES ETCK, TCK1, TCK2 Clock Period t1 25 ns 30% DC ETCK, TCK1, TCK2 Clock Low Time t2 17.5 ns ETCK, TCK1, TCK2 Clock High Time t3 7.5 ns ETCK to ETDI, ETMS Setup Time TCK1 to TDI1, TMS1 Setup Time TCK2 to TDI2, TMS2 Setup Time t4 3 ns ETCK to ETDI, ETMS Hold Time TCK1 to TDI1, TMS1 Hold Time TCK2 to TDI2, TMS2 Hold Time t5 3 ns ETCK to ETDO Delay TCK1 to TDO1 Delay TCK2 to TDO2 Delay t6 15 ns ETCK to ETDO High-Impedance Delay TCK1 to TDO1 High-Impedance Delay TCK2 to TDO2 High-Impedance Delay t7 17.5 ns Note 1: TCK should be stopped low. Note 2: Interface timing in Table 11-1 is to/from the arbitrated master. Note 3: TCK corresponds to each master port clock when being used to configure the core JTAG controller, e.g., ETCK or TCK1 or TCK2. Note 4: TDI, TMS correspond to the master port TDI, TMS when being used to configure the core JTAG controller, e.g., ETDI, ETMS or TDI1, TMS1 or TDI2, TMS2. Note 5: TDO corresponds to the master port TDO when being used to configure the core JTAG controller, e.g., ETDO or TDO1 or TDO2. Note 6: The configuration signals (TRST1, TRST2, ECFG) and the master request signals (TMREQ1, TMREQ2, EREQ) are asynchronous. TCK, TDI, TMS should be low when switching masters to avoid the possibility of glitching the secondary port whose address is in the Secondary Port Selection Register (SPSR). Another method to avoid glitching the secondary port is to set the Secondary Port Selection Register (SPSR) to 00000 when changing the arbitrated master. Figure 11-1. Switch TAP Controller Interface Timing Diagram ETCK TCK1 TCK2 ETDO TDO1 TDO2 T2 T3 ETDI, ETMS TDI1, TMS1 TDI2, TMS2

11.2 Transparent Mode Master/Slave Port Timing

Table 11-2. Master/Slave Port Timing (VDD = 3.3V ±5%, TA = -40°C to +85°C.) (See Figure 11-2.) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES ETCK, TCLK1, TCLK2 to STCKx Latency ETMS, TMS1, TMS2 to STMSx Latency ETDI, TDI1, TDI2 to STDIx Latency t1 3 11 ns 1 ETCK, TCLK1, TCLK2 to STCKx Skew ETMS, TMS1, TMS2 to STMSx Skew ETDI, TDI1, TDI2 to STDIx Skew t2 0.8 4.0 ns 2, 3 STDOx to ETDO, TDO1, TDO2 Latency t3 3 11 ns 4 TDO + TCK t5 11.4 16 26.4 ns 5 Note 1: Delay (latency) from a particular master port signal to the corresponding slave port signal. Note 2: Skew values are with respect to a signal from the arbitrated master to the same signal on the selected secondary slave port. Note 3: Skew from any set of two signals at a master port to the corresponding two signals at the selected slave port. Note 4: Delay path from a selected slave port STDO to the arbitrated master’s TDO. Note 5: Half-cycle path from falling edge STCK/STDO (launch) to rising edge TCK/TDO (capture), pass-through path (see Figure 11-2). Note 6: TCK corresponds to each master port clock when being used to configure the core JTAG controller, e.g., ETCK or TCK1 or TCK2. TDI, TMS correspond to the master port TDI, TMS, e.g., ETDI, ETMS or TDI1, TMS1 or TDI2, TMS2. TDO corresponds to the master port TDO when being used to configure the core JTAG controller, e.g., ETDO or TDO1 or TDO2. STDI1–STDI18, STMS1–STMS18. STDO corresponds to the slave port STDO1–STDO18. Figure 11-2. Transparent Mode Master/Slave Port Timing Diagram ETCK, TCK1, TCK2 ETMS, TMS1, TMS2 ETDI, TDI1, TDI2 STCKn, STMSn, STDIn STDOn ETDO, TDO1, TDO2 t1 t2 t3 t4

11.3 Periphery JTAG Interface Timing

Table 11-3. Periphery JTAG Interface Timing (VDD = 3.3V ±5%, TA = -40°C to +85°C.) (See Figure 11-3.) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES PTCLK Clock Period t1 100 ns 1 PTCLK Clock High/Low Time t2/t3 30 ns 2 PTCLK to PTDI, PTMS Setup Time t4 20 ns PTCLK to PTDI, PTMS Hold Time t5 10 ns PTCLK to PTDO Delay t6 2 10 ns PTCLK to PTDO High-Impedance Delay t7 2 10 ns PTRST Width Low Time t8 50 ns Note 1: Clock period for the periphery boundary scan is 100ns (min). Note 2: Clock can be stopped high or low. Figure 11-3. Periphery JTAG Interface Timing Diagram PTCLK PTDO T2 T3 PTDI PTMS PTRST

1. Pin Configuration

1. Package Information (The package drawing(s) in this data sheet may not refl ect the most current specifications. The package number provided for each package is a link to the latest package outline information.) 13.1 144-Pin LQFP ( 56-G6037-001)

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 50 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products. 14. Document Revision History REVISION DESCRIPTION 072707 New Product Release.