AN560

Microchip Technology

Lowpower 3-wire non-volatile memories 1994 - 2002

Manufacturer: Microchip Technology

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© 1994 Microchip Technology Inc. DS00560D-page 1 Using the 93LC56 and 93LC66 AN560 Using the 93LC56 and 93LC66 INTRODUCTION The Microchip Technology Inc. 93LC56/66 are low- power 3-wire non-volatile memories and are suitable for many embedded system code and data storage applica- tions. These devices are easily interfaced to most micro- controllers in today's market place, but Microchip’s 8-bit RISC series PIC16CXX offers the best code density of any microcontroller on the market today. Using the PIC16C54, the assembly programs contained in this application note have been fully tested and provide the correct timing and 3-wire sequences to fully operate the 93LC56/66 in a PIC16CXX-based embedded applica- tion. The PIC16C54 was clocked at a 10MHz frequency. This application note is intended to provide the engineer with readily available stand-alone code modules to accomplish all of the necessary functions to utilize these devices in a low power application using the efficient PIC16C54 microcontroller. The 93 series of devices have essentially four I/O pins: CS Chip Select CLK Clock DI Data In DO Data Out This series of devices use a series of commands to accomplish the normal memory functions. These are READ, WRITE, EWEN, ERASE, ERAL, WRAL, EWDS. For a more detailed discussion of the function of these devices reference the appropriate data sheet and AN536, also published by Microchip Technology. The following programs are included in this application note and are fully functional stand-alone modules. They are intended for use by those who are not already familiar with interfacing a PIC16CXX microcontroller to a 93 series device. For those with more experience, please refer to application note AN530. 3-Wire Byte Read Program – Start Bit Routine – Receive Data Routine – Bit Out Routine – Transmit Data Routine – Power-up Routine – Read Routine 3-Wire Byte Write Program – Delay Routine – Start Bit Routine – Bit Out Routine – Transmit Data Routine – Power-up Routine – Erase/Write Enable Routine (EWEN) – Byte Write Routine – Erase/Write Disable Routine (EWDS) 3-Wire Byte Write with Data Polling Program – Data Polling Delay Routine – Start Bit Routine – Bit Out Routine – Transmit Data Routine – Power-up Routine – Erase/Write Enable Routine – Write Routine – Erase/Write Disable Routine (EWDS) 3-Wire Sequential Read Program – Delay Routine – Start Bit Routine – Bit In Routine – Receive Data Routine – Bit Out Routine – Transmit Data Routine – Power-up Routine – Read Routine Author: Bruce Negley Memory Products Division 8-99

0001 LIST P=16C54,c=132

0003 ; 3-Wire Byte Read Program (80 bytes) 0004 ; 0005 ; This program demonstrates how to interface a 0006 ; Microchip PIC16C54 to a 93LC56 or 93LC66 Serial EE 0007 ; device. This program will read 8 consecutive addresses 0008 ; in the ‘random read’ mode. This means that the opcode 0009 ; and address for each byte will be sent to the device. 0010 ; This program will repeat forever. 0011 ; 0012 ; Another, more efficient method of reading consecutive 0013 ; addresses is called the ‘sequential read’ mode. This 0014 ; involves sending the opcode and address for the first 0015 ; byte to read, then continuing to provide clocks for the 0016 ; next addresses. The device will automatically increment 0017 ; the address. An example of the sequential read mode is 0018 ; provided in the ‘3wseqr.asm’ file. 0019 ; 0020 ; This program communicates to the serial EE in the 0021 ; x16 mode, and ASSUMES THE USER HAS SET THE ORG PIN 0022 ; ON THE DEVICE TO Vcc. 0023 ; 0024 ; Timing is based on using the PIC16C54 in ‘XT’ mode 0025 ; using a 4Mhz crystal. Clock speeds to the serial EE 0026 ; will be approximately 50 kHz for this setup. 0027 ; 0028 ; PIC16C54 to Serial EE Connections: 0029 ; 0030 ; PIC16C54 Serial EE 0032 ; Pin 10 (RB4) —> Chip Select 0033 ; Pin 11 (RB5) —> Clock 0034 ; Pin 12 (RB6) —> Data In 0035 ; Pin 13 (RB7) —> Data Out 0036 ; ORG = Vcc 0037 ; 0039 ; Register Assignments 0041 0003 status equ 3h ; status register 0042 0005 port_a equ 5h ; port 5 (port_a) 0043 0006 port_b equ 6h ; port 6 (port b) comm lines to serial EE 0044 000A eeprom equ 0ah ; bit buffer 0045 000C addr equ 0ch ; address register 0046 000D datai equ 0dh ; stored data input reg. 0047 000E datao equ 0eh ; stored data output reg. 0048 0010 txbuf equ 10h ; transmit buffer 0049 0011 count equ 11h ; bits transmitted so far 0050 0012 bits equ 12h ; bits to transmit 0051 0013 bytcnt equ 13h ; byte counter for read routine 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:10 1994 Page 2 Line PC Opcode 0052 0015 loops equ 15h ; delay loop counter 0053 0016 loops2 equ 16h ; delay loop counter 0054 0017 hbyte equ 17h ; high byte for input data 0055 0018 lbyte equ 18h ; low byte for input data 0057 ; Bit Assignments 0059 0007 di equ 7 ; eeprom input 0060 0006 do equ 6 ; eeprom output 8-100

© 1994 Microchip Technology Inc. DS00560D-page 3 Using the 93LC56 and 93LC66 0061 0007 datout equ 7 ; data out line (port_b) 0062 0006 datin equ 6 ; data in line (port_b) 0063 0005 sclk equ 5 ; clock line (port_b) 0064 0004 chpsel equ 4 ; chip select line (port_b) 0065 ; 0067 0000 org 01ffh 0068 01FF 0A33 begin goto PWRUP ; set the reset vector 0069 0000 org 000h 0070 0000 0A33 goto PWRUP 0071 ; 0073 ; Start Bit Subroutine 0074 ; this routine generates a start bit 0075 ; (Chip select and DI high when clock goes high)

0077 BSTART

0078 0001 04C6 bcf port_b,datin ; set datain and chipselect lines 0079 0002 0486 bcf port_b,chpsel ; low just to check operation 0080 0003 04A6 bcf port_b,sclk ; make sure clock starts low too. 0081 0004 0000 nop 0082 ; 0083 0005 0586 bsf port_b,chpsel ; set chip select line high 0084 0006 05C6 bsf port_b,datin ; set data in line high 0085 0007 0000 nop 0086 0008 05A6 bsf port_b,sclk ; set the clock line high to 0087 ; generate the start bit 0088 0009 0000 nop 0089 000A 0000 nop 0090 000B 04A6 bcf port_b,sclk ; set clock low again 0091 000C 0800 retlw 0 0092 ; 0094 ; BITIN routine reads one bit of data from the 0095 ; serial EE device and stores it in ‘di’

0097 BITIN

0098 000D 05EA bsf eeprom,di ; assume input bit is high 0099 000E 05A6 bsf port_b,sclk ; set clock line high 0100 000F 0000 nop ; 0101 0010 07E6 btfss port_b,datout ; read the data bit 0102 0011 04EA bcf eeprom,di ; input bit was low 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:10 1994 Page 3 Line PC Opcode 0103 0012 04A6 bcf port_b,sclk ; set clock line low 0104 ; 0105 0013 0800 retlw 0 ; 0106 0108 ; Receive data routine 0109 ; This routine reads one byte of data from the part 0110 ; into the ‘datai’ register. 0112 RX 0113 0014 006D clrf datai ; clear input buffer 0114 0015 0C08 movlw .8 ; set # bits to 8 0115 0016 0031 movwf count 0116 0017 0403 bcf status,0 ; make sure carry bit is low 0117 0018 036D RXLP rlf datai ; rotate the buffer left 1 bit 0118 0019 090D call BITIN ; read 1 bit 0119 001A 040D bcf datai,0 ; assume the input bit was low 0120 001B 06EA btfsc eeprom,di ; check the bit 0121 001C 050D bsf datai,0 ; set high if neccessary 0122 001D 02F1 decfsz count ; 8 bits done? 0123 001E 0A18 goto RXLP ; no, do another 0124 001F 0800 retlw 0 8-101

DS00560D-page 4 © 1994 Microchip Technology Inc. Using the 93LC56 and 93LC66 0125 ; 0127 ; BITOUT routine 0128 ; This routine takes one bit of data in ‘do’ and 0129 ; transmits it to the serial EE device

0131 BITOUT

0132 0020 07CA btfss eeprom,do ; check state of data bit 0133 0021 0A24 goto bitlow ; low, goto bitlow 0134 0022 05C6 bsf port_b,datin ; high, set datain high 0135 0023 0A25 goto clkout ; and clock it 0136 ; 0137 0024 04C6 bitlow bcf port_b,datin ; output a logic low 0138 0025 05A6 clkout bsf port_b,sclk ; set clock line high 0139 0026 0000 nop 0140 0027 04A6 bcf port_b,sclk ; return clock line low 0141 0028 0800 retlw 0 0142 ; 0144 ; Transmit Data Subroutine 0145 ; This routine takes the byte of data stored in the 0146 ; ‘datao’ register and transmits it to the serial EE device. 0148 TX 0149 0029 0212 movf bits,w ; set the number of bits to xmit 0150 002A 0031 movwf count 0151 ;

0152 TXLP

0153 002B 04CA bcf eeprom,do ; assume bit 7 is low 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:10 1994 Page 4 Line PC Opcode 0154 002C 06F0 btfsc txbuf,7 ; is bit 7 clear? 0155 002D 05CA bsf eeprom,do ; no, set data bit =1 0156 002E 0920 call BITOUT ; transmit 1 bit to serial EE 0157 002F 0370 rlf txbuf ; rotate txbuf left 0158 0030 02F1 decfsz count ; all bits done? 0159 0031 0A2B goto TXLP ; no, do another bit 0160 0032 0800 retlw 0 ; yes, jump out 0161 ; 0163 ; POWER-UP ROUTINE 0164 ; This is the program entry point, which in this case simply 0165 ; sets the port_a I/O lines and directs control to the 0166 ; read routine.

0168 PWRUP

0169 ; 0170 0033 0C00 movlw b’00000000' 0171 0034 0005 tris port_a ; set port_a as all output 0172 0035 0065 clrf port_a ; all lines low 0173 0174 0036 0C80 movlw b’10000000' 0175 0037 0006 tris port_b ; set RB7 as input, rest output; 0176 ; 0177 ; Fall through and do the read 0178 ; 0180 ; READ ROUTINE 0181 ; This routine reads 8 consecutive addresses in 0182 ; random mode starting at address 0. This is done in 0183 ; x16 mode and will repeat forever.

0185 READ

0186 ; 0187 0038 0C00 movlw .0 ; set starting address to 00 0188 0039 002C movwf addr ; 8-102

© 1994 Microchip Technology Inc. DS00560D-page 5 Using the 93LC56 and 93LC66 0189 003A 0C08 movlw .8 ; set number of addresses to 0190 003B 0033 movwf bytcnt ; read as 8 0191 ; 0192 003C 0901 rbyte call BSTART ; generate the start bit 0193 003D 0C02 movlw .2 ; set # bits to 2 0194 003E 0032 movwf bits ; 0195 003F 0C80 movlw b’10000000' ; get opcode (10b) 0196 0040 0030 movwf txbuf ; into output buffer 0197 0041 0929 call TX ; and transmit it 0198 0042 0C08 movlw .8 ; 0199 0043 0032 movwf bits ; set number of bits to 8 0200 0044 020C movf addr,w ; get the address 0201 0045 0030 movwf txbuf ; into the output buffer 0202 0046 0929 call TX ; and transmit it 0203 0204 0047 0914 call RX ; read the high byte 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:10 1994 Page 5 Line PC Opcode 0205 0048 020D movf datai,w ; move input data to w 0206 0049 0037 movwf hbyte ; xfer it to high byte 0207 0208 004A 0914 call RX ; read the low byte 0209 004B 020D movf datai,w ; move input data to w 0210 004C 0037 movwf hbyte ; xfer it to low byte 0211 0212 004D 0486 bcf port_b,chpsel ; clear the chip select line 0213 0214 004E 02AC incf addr ; add 1 to the address 0215 004F 02F3 decfsz bytcnt ; have all bytes been read? 0216 0050 0A3C goto rbyte ; no, read another byte 0217 0051 0A38 goto READ ; yes, start over 0218 0000 END 8-103

DS00560D-page 6 © 1994 Microchip Technology Inc. Using the 93LC56 and 93LC66 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:06 1994 Page 1 Line PC Opcode 0003 ; 3-Wire Byte Write Program (106 bytes) 0004 ; 0005 ; This program demonstrates how to interface a 0006 ; Microchip PIC16C54 to a 93LC56 or 93LC66 Serial EE 0007 ; device. This program will execute the erase/write enable 0008 ; command, write to 8 consecutive addresses, and then 0009 ; execute the erase/write disable command. This 0010 ; sequence will repeat forever. 0011 ; 0012 ; After each byte is written, time must be given to the 0013 ; device for it to complete the write cycle before 0014 ; the next command can be sent. The easiest solution 0015 ; is to consult the data book for the maximum write 0016 ; cycle time and just wait that long before the next 0017 ; command is sent. This program demonstrates that 0018 ; solution. 0019 ; 0020 ; Another, more efficient method of determining when the 0021 ; write cycle is complete is called ‘data polling.’ This 0022 ; method is demonstrated in the program “3wdpoll.” 0023 ; 0024 ; This program communicates to the serial EE in the 0025 ; x16 mode, and ASSUMES THE USER HAS SET THE ORG PIN 0026 ; ON THE DEVICE TO Vcc. 0027 ; 0028 ; Timing is based on using the PIC16C54 in ‘XT’ mode 0029 ; using a 4Mhz crystal. Clock speeds to the serial EE 0030 ; will be approximately 40 kHz for this setup. 0031 ; 0032 ; PIC16C54 to Serial EE Connections: 0033 ; 0034 ; PIC16C54 Serial EE 0036 ; Pin 10 (RB4) —> Chip Select 0037 ; Pin 11 (RB5) —> Clock 0038 ; Pin 12 (RB6) —> Data In 0039 ; Pin 13 (RB7) —> Data Out 0040 ; ORG=Vcc 0041 ; 0043 ; Register Assignments 0045 0005 port_a equ 5h ; port 5 (port_a) 0046 0006 port_b equ 6h ; port 6 (port b) comm lines to serial EE 0047 000A eeprom equ 0ah ; bit buffer 0048 000C addr equ 0ch ; address register 0049 000D datai equ 0dh ; stored data input reg. 0050 000E datao equ 0eh ; stored data output reg. 0051 0010 txbuf equ 10h ; transmit buffer 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:06 1994 Page 2 Line PC Opcode 0052 0011 count equ 11h ; bits transmitted so far 0053 0012 bits equ 12h ; bits to transmit 0054 0013 bytcnt equ 13h ; byte counter for write routine 0055 0015 loops equ 15h ; delay loop counter 0056 0016 loops2 equ 16h ; delay loop counter ; 0058 ; Bit Assignments 0060 0007 di equ 7 ; eeprom input 8-104

© 1994 Microchip Technology Inc. DS00560D-page 7 Using the 93LC56 and 93LC66 0061 0006 do equ 6 ; eeprom output 0062 0007 datout equ 7 ; data out line (port_b) 0063 0006 datin equ 6 ; data in line (port_b) 0064 0005 sclk equ 5 ; clock line (port_b) 0065 0004 chpsel equ 4 ; chip select line (port_b) 0066 ; 0068 0000 org 01ffh 0069 01FF 0A2F begin goto PWRUP ; set the reset vector 0070 0000 org 000h 0071 0000 0A2F goto PWRUP 0072 ; 0074 ; DELAY ROUTINE 0075 ; This routine takes the value in ‘loops’ 0076 ; and multiplies it times 1 millisecond to 0077 ; determine delay time.

0079 WAIT

0080 ; 0081 0001 0C6E top movlw .110 ; timing adjustment variable 0082 0002 0036 movwf loops2 0083 0003 0000 top2 nop ; sit and wait 0084 0004 0000 nop 0085 0005 0000 nop 0086 0006 0000 nop 0087 0007 0000 nop 0088 0008 0000 nop 0089 0009 02F6 decfsz loops2 ; inner loops complete? 0090 000A 0A03 goto top2 ; no, go again 0091 ; 0092 000B 02F5 decfsz loops ; outer loops complete? 0093 000C 0A01 goto top ; no, go again 0094 000D 0800 retlw 0 ; yes, return from sub 0095 ; 0097 ; Start Bit Subroutine 0098 ; this routine generates a start bit 0099 ; (Chip select and DI high when clock goes high)

0101 BSTART

0102 000E 0C8F movlw b’10001111' 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:06 1994 Page 3 Line PC Opcode 0103 000F 0006 tris port_b ; set port b for output 0104 ; except for the data out line 0105 0010 04C6 bcf port_b,datin ; set datain and chipselect lines 0106 0011 0486 bcf port_b,chpsel ; low just to check operation 0107 0012 04A6 bcf port_b,sclk ; make sure clock starts low too. 0108 0013 0000 nop 0109 ; 0110 0014 0586 bsf port_b,chpsel ; set chip select line high 0111 0015 05C6 bsf port_b,datin ; set data in line high 0112 0016 0000 nop 0113 0017 05A6 bsf port_b,sclk ; set the clock line high to 0114 ; generate the start bit 0115 0018 0000 nop 0116 0019 0000 nop 0117 001A 04A6 bcf port_b,sclk ; set clock low again 0118 001B 0800 retlw 0 0119 ; 0121 ; BITOUT routine 0122 ; This routine takes one bit of data in ‘do’ and 0123 ; transmits it to the serial EE device 8-105

0125 BITOUT

0126 001C 07CA btfss eeprom,do ; check state of data bit 0127 001D 0A20 goto bitlow ; low, goto bitlow 0128 001E 05C6 bsf port_b,datin ; high, set datain high 0129 001F 0A21 goto clkout ; and clock it 0130 ; 0131 0020 04C6 bitlow bcf port_b,datin ; output a logic low 0132 0021 05A6 clkout bsf port_b,sclk ; set clock line high 0133 0022 0000 nop 0134 0023 04A6 bcf port_b,sclk ; return clock line low 0135 0024 0800 retlw 0 0136 ; 0138 ; Transmit Data Subroutine 0139 ; This routine takes the byte of data stored in the 0140 ; ‘datao’ register and transmits it to the serial EE device. 0142 TX 0143 0025 0212 movf bits,w ; set the number of bits to xmit 0144 0026 0031 movwf count 0145 ;

0146 TXLP

0147 0027 04CA bcf eeprom,do ; assume bit 7 is low 0148 0028 06F0 btfsc txbuf,7 ; is bit 7 clear? 0149 0029 05CA bsf eeprom,do ; no, set data bit =1 0150 002A 091C call BITOUT ; transmit 1 bit to serial EE 0151 002B 0370 rlf txbuf ; rotate txbuf left 0152 002C 02F1 decfsz count ; all bits done? 0153 002D 0A27 goto TXLP ; no, do another bit 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:06 1994 Page 4 Line PC Opcode 0154 002E 0800 retlw 0 ; yes, jump out 0155 ; 0157 ; POWER-UP ROUTINE 0158 ; This is the program entry point, which in this case simply 0159 ; sets the port_a I/O lines and directs control to the 0160 ; erase/write enable routine.

0162 PWRUP

0163 ; 0164 002F 0C00 movlw b’00000000' 0165 0030 0005 tris port_a ; set port_a as all output 0166 0031 0065 clrf port_a ; all lines low 0167 0168 0032 0C80 movlw b’10000000' 0169 0033 0006 tris port_b ; set RB7 as input, rest output; 0170 ; 0171 ; Fall through and do erase/write enable 0172 ; 0174 ; EWEN (Erase/Write ENable Routine) 0175 ; this routine enables the dut for erasing and 0176 ; writing. This must be done prior to any erase,write 0177 ; eral,wral instructions.

0179 EWEN

0180 ; 0181 0034 090E call BSTART ; generate a start bit 0182 ; 0183 0035 0C02 movlw .2 ; set # bits to 2 0184 0036 0032 movwf bits ; 0185 0037 0C00 movlw b’00000000' ; get the opcode (00b) 0186 0038 0030 movwf txbuf ; into the output buffer 0187 0039 0925 call TX ; and transmit it 0188 003A 0C08 movlw .8 ; set # bits to 8 8-106

© 1994 Microchip Technology Inc. DS00560D-page 9 Using the 93LC56 and 93LC66 0189 003B 0032 movwf bits ; 0190 003C 0CC0 movlw b’11000000' ; get opcode and address 0191 ; (11XXXXXX) 0192 003D 0030 movwf txbuf ; into output buffer 0193 003E 0925 call TX ; and transmit it 0194 003F 0486 bcf port_b,chpsel ; set chip select line low 0195 0040 0000 nop 0196 ; 0197 ; Now continue on to the write command 0198 ; 0200 ; Byte Write Routine 0201 ; This routine writes an AA55h pattern into 0202 ; 8 consecutive addresses starting at address 00. 0203 ; A delay of about 10ms is given after each byte 0204 ; for the write cycle to complete. 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:06 1994 Page 5 Line PC Opcode 0205 ; The write is done in the x16 mode: the user must 0206 ; have the ORG pin tied to Vcc on the device

0208 WRITE

0209 ; 0210 0041 0C00 movlw .0 ; set starting address to 00 0211 0042 002C movwf addr ; 0212 0043 0C08 movlw .8 ; set number of bytes to write as 8 0213 0044 0033 movwf bytcnt ; 0214 ; 0215 0045 090E topwr call BSTART ; generate the start bit 0216 ; 0217 0046 0C02 movlw .2 ; set # bits to 2 for the opcode 0218 0047 0032 movwf bits ; 0219 0048 0C40 movlw b’01000000' ; get opcode (01b) 0220 0049 0030 movwf txbuf ; into the transmit buffer 0221 004A 0925 call TX ; and send it 0222 ; 0223 004B 0C08 movlw .8 ; set # of bits to 8 for the 0224 004C 0032 movwf bits ; address 0225 004D 020C movf addr,w ; get address counter 0226 004E 0030 movwf txbuf ; into output buffer 0227 004F 0925 call TX ; and send it 0228 0050 0CAA movlw b’10101010' ; get upper byte of data (AAh) 0229 0051 0030 movwf txbuf ; into the transmit buffer 0230 0052 0925 call TX ; and send it 0231 0053 0C55 movlw b’01010101' ; get lower byte of data (55h) 0232 0054 0030 movwf txbuf ; into transmit buffer 0233 0055 0925 call TX ; and send it 0234 ; 0235 0056 0486 bcf port_b,chpsel ; clear the chip select line 0236 ; to initiate write cycle 0237 ; 0238 0057 0C0A movlw .10 ; 0239 0058 0035 movwf loops ; set delay time to 10mS 0240 0059 0901 call WAIT ; and wait 0241 ; 0242 005A 02AC incf addr ; increment address counter 0243 005B 02F3 decfsz bytcnt ; all bytes written? 0244 005C 0A45 goto topwr ; no, do another 0245 ; yes, go on 0246 ; 0247 ; Now continue on to the erase/write disable command 0248 ; 0250 ; EWDS (Erase/Write Disable Routine) 0251 ; This routine executes the erase/write disable command 0252 ; which prevents the contents of the array from being 8-107

0256 EWDS

0257 ; 0258 005D 090E call BSTART ; generate a start bit 0259 ; 0260 005E 0C02 movlw .2 ; set # bits to 2 0261 005F 0032 movwf bits ; 0262 0060 0C00 movlw b’00000000' ; get the opcode (00b) 0263 0061 0030 movwf txbuf ; into the output buffer 0264 0062 0925 call TX ; and transmit it 0265 0063 0C08 movlw .8 ; set # bits to 8 0266 0064 0032 movwf bits ; 0267 0065 0C00 movlw b’00000000' ; get opcode and address 0268 ; (00XXXXXX) 0269 0066 0030 movwf txbuf ; into output buffer 0270 0067 0925 call TX ; and transmit it 0271 0068 0486 bcf port_b,chpsel ; set chip select line low 0272 0069 0000 nop 0273 006A 0A34 goto EWEN ; start all over 0274 ; 0275 0000 END 8-108

© 1994 Microchip Technology Inc. DS00560D-page 11 Using the 93LC56 and 93LC66 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:00 1994 Page 1 Line PC Opcode 0003 ; 3-Wire Byte Write with Data Poll Program (107 bytes) 0004 ; 0005 ; This program demonstrates how to interface a 0006 ; Microchip PIC16C54 to a 93LC56 or 93LC66 Serial EE 0007 ; device. This program will execute the erase/write enable 0008 ; command, write to 8 consecutive addresses, and then 0009 ; use the ‘data polling’ method to determine when the 0010 ; write cycle is complete. The program then executes 0011 ; the erase/write disable command. This sequence will 0012 ; repeat forever. 0013 ; 0014 ; When writing to a 3-wire serial EE device, the 0015 ; internally timed write cycle will begin after 0016 ; the opcode, address and data are sent to the 0017 ; device. There are two ways to make sure that the 0018 ; cycle is complete before you send it another command. 0019 ; The simplest method is to simply wait for the maximum 0020 ; write cycle time, which can be obtained from the data book. 0021 ; A more efficient method is “Data polling.” This is 0022 ; done by toggling the chip select line low and then 0023 ; back high after the opcode, address and data are sent. 0024 ; The chip select line must be low for at least 250ns 0025 ; before bringing it high again. The device will pull 0026 ; the data out line low at that point, and set it high 0027 ; when the write cycle is complete. The user can then check 0028 ; or “poll” the dataout line until it goes high before 0029 ; sending the next command. 0030 ; 0031 ; As an option, the user can connect a LED to pin 18 0032 ; on the PIC16C54 (use about a 1K resistor in series) as a 0033 ; timeout indicator. This LED will come on if the 0034 ; data polling is unsuccessful and the device being 0035 ; programmed does not respond. This can be tested by 0036 ; simply running the program with no part in the socket. 0037 ; 0038 ; This program communicates to the serial EE in the 0039 ; x16 mode, and ASSUMES THE USER HAS SET THE ORG PIN 0040 ; ON THE DEVICE TO Vcc. 0041 ; 0042 ; Timing is based on using the PIC16C54 in ‘XT’ mode 0043 ; using a 4Mhz crystal. Clock speeds to the serial EE 0044 ; will be approximately 50 kHz for this setup. 0045 ; 0046 ; PIC16C54 to Serial EE Connections: 0047 ; 0048 ; PIC16C54 Serial EE 0050 ; Pin 10 (RB4) —> Chip Select 0051 ; Pin 11 (RB5) —> Clock 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:00 1994 Page 2 Line PC Opcode 0052 ; Pin 12 (RB6) —> Data In 0053 ; Pin 13 (RB7) —> Data Out 0054 ; ORG=Vcc 0055 ; 0057 ; Register Assignments 0059 0005 port_a equ 5h ; port 5 (port_a) 0060 0006 port_b equ 6h ; port 6 (port b) used comm lines to serial EE 8-109

DS00560D-page 12 © 1994 Microchip Technology Inc. Using the 93LC56 and 93LC66 0061 000A eeprom equ 0ah ; bit buffer 0062 000C addr equ 0ch ; address register 0063 000D datai equ 0dh ; stored data input reg. 0064 000E datao equ 0eh ; stored data output reg. 0065 0010 txbuf equ 10h ; transmit buffer 0066 0011 count equ 11h ; bits transmitted so far 0067 0012 bits equ 12h ; bits to transmit 0068 0013 bytcnt equ 13h ; byte counter for write routine 0069 0015 loops equ 15h ; delay loop counter 0070 0016 loops2 equ 16h ; delay loop counter 0072 ; Bit Assignments 0074 0007 di equ 7 ; eeprom input 0075 0006 do equ 6 ; eeprom output 0076 0007 datout equ 7 ; data out line (port_b) 0077 0006 datin equ 6 ; data in line (port_b) 0078 0005 sclk equ 5 ; clock line (port_b) 0079 0004 chpsel equ 4 ; chip select line (port_b) 0080 0001 timeout equ 1 ; write cycle timeout warning (port_a) 0081 ; 0083 0000 org 01ffh 0084 01FF 0A26 begin goto PWRUP ; set the reset vector 0085 0000 org 000h 0086 0000 0A26 goto PWRUP 0087 ; 0089 ; DATA POLL DELAY ROUTINE 0090 ; This routine delays 100 us is 0091 ; used for delay between polls 0093 dpdelay 0094 ; 0095 0001 0C19 movlw .25 ; timing adjustment variable 0096 0002 0036 movwf loops2 0097 0003 0000 top nop 0098 0004 02F6 decfsz loops2 ; loops complete? 0099 0005 0A03 goto top ; no, go again 0100 ; 0101 0006 0800 retlw 0 ; yes, return from sub 0102 ; 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:00 1994 Page 3 Line PC Opcode 0104 ; Start Bit Subroutine 0105 ; this routine generates a start bit 0106 ; (Chip select and DI high when clock goes high)

0108 BSTART

0109 0007 04C6 bcf port_b,datin ; set datain and chipselect lines 0110 0008 0486 bcf port_b,chpsel ; low just to check operation 0111 0009 04A6 bcf port_b,sclk ; make sure clock starts low too. 0112 000A 0000 nop 0113 ; 0114 000B 0586 bsf port_b,chpsel ; set chip select line high 0115 000C 05C6 bsf port_b,datin ; set data in line high 0116 000D 0000 nop 0117 000E 05A6 bsf port_b,sclk ; set the clock line high to 0118 ; generate the start bit 0119 000F 0000 nop 0120 0010 0000 nop 0121 0011 04A6 bcf port_b,sclk ; set clock low again 0122 0012 0800 retlw 0 0123 ; 8-110

0129 BITOUT

0130 0013 07CA btfss eeprom,do ; check state of data bit 0131 0014 0A17 goto bitlow ; low, goto bitlow 0132 0015 05C6 bsf port_b,datin ; high, set datain high 0133 0016 0A18 goto clkout ; and clock it 0134 ; 0135 0017 04C6 bitlow bcf port_b,datin ; output a logic low 0136 0018 05A6 clkout bsf port_b,sclk ; set clock line high 0137 0019 0000 nop 0138 001A 04A6 bcf port_b,sclk ; return clock line low 0139 001B 0800 retlw 0 0140 ; 0142 ; Transmit Data Subroutine 0143 ; This routine takes the byte of data stored in the 0144 ; ‘datao’ register and transmits it to the serial EE device. 0146 TX 0147 001C 0212 movf bits,w ; set the number of bits to xmit 0148 001D 0031 movwf count 0149 ;

0150 TXLP

0151 001E 04CA bcf eeprom,do ; assume bit 7 is low 0152 001F 06F0 btfsc txbuf,7 ; is bit 7 clear? 0153 0020 05CA bsf eeprom,do ; no, set data bit =1 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:00 1994 Page 4 Line PC Opcode 0154 0021 0913 call BITOUT ; transmit 1 bit to serial EE 0155 0022 0370 rlf txbuf ; rotate txbuf left 0156 0023 02F1 decfsz count ; all bits done? 0157 0024 0A1E goto TXLP ; no, do another bit 0158 0025 0800 retlw 0 ; yes, jump out 0159 ; 0161 ; POWER-UP ROUTINE 0162 ; This is the program entry point, which in this case simply 0163 ; sets the port_a I/O lines and directs control to the 0164 ; erase/write enable routine.

0166 PWRUP

0167 ; 0168 0026 0C00 movlw b’00000000' 0169 0027 0005 tris port_a ; set port_a as all output 0170 0028 0065 clrf port_a ; all lines low 0171 0172 0029 0C80 movlw b’10000000' 0173 002A 0006 tris port_b ; set RB7 as input, rest output; 0174 ; 0175 ; Fall through and do erase/write enable 0176 ; 0178 ; EWEN (Erase/Write ENable Routine) 0179 ; this routine enables the dut for erasing and 0180 ; writing. This must be done prior to any erase,write 0181 ; eral,wral instructions.

0183 EWEN

0184 ; 0185 002B 0907 call BSTART ; generate a start bit 0186 ; 0187 002C 0C02 movlw .2 ; set # bits to 2 0188 002D 0032 movwf bits ; 8-111

DS00560D-page 14 © 1994 Microchip Technology Inc. Using the 93LC56 and 93LC66 0189 002E 0C00 movlw b’00000000' ; get the opcode (00b) 0190 002F 0030 movwf txbuf ; into the output buffer 0191 0030 091C call TX ; and transmit it 0192 0031 0C08 movlw .8 ; set # bits to 8 0193 0032 0032 movwf bits ; 0194 0033 0CC0 movlw b’11000000' ; get opcode and address 0195 ; (11XXXXXX) 0196 0034 0030 movwf txbuf ; into output buffer 0197 0035 091C call TX ; and transmit it 0198 0036 0486 bcf port_b,chpsel ; set chip select line low 0199 0037 0000 nop 0200 ; 0201 ; Now continue on to the write command 0202 ; 0204 ; WRITE 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:00 1994 Page 5 Line PC Opcode 0205 ; This routine writes a AA55h pattern into 0206 ; 8 consecutive addresses starting at address 00. 0207 ; It will then ‘poll’ the data out line to determine 0208 ; when the write cycle is complete. If the cycle has 0209 ; not completed within 20 ms, then it will continue 0210 ; anyway and turn the timeout fail LED on. 0211 ; The write is done in the x16 mode: the user must 0212 ; have the ORG pin tied to Vcc on the device. This 0213 ; program will repeat forever.

0215 WRITE

0216 ; 0217 0038 0C00 movlw .0 ; set starting address to 00 0218 0039 002C movwf addr ; 0219 003A 0C08 movlw .8 ; set number of bytes to write as 8 0220 003B 0033 movwf bytcnt ; 0221 ; 0222 003C 0907 topwr call BSTART ; generate the start bit 0223 ; 0224 003D 0C02 movlw .2 ; set # bits to 2 for the opcode 0225 003E 0032 movwf bits ; 0226 003F 0C40 movlw b’01000000' ; get opcode (01b) 0227 0040 0030 movwf txbuf ; into the transmit buffer 0228 0041 091C call TX ; and send it 0229 ; 0230 0042 0C08 movlw .8 ; set # of bits to 8 for the 0231 0043 0032 movwf bits ; address 0232 0044 020C movf addr,w ; get address counter 0233 0045 0030 movwf txbuf ; into output buffer 0234 0046 091C call TX ; and send it 0235 0047 0CAA movlw b’10101010' ; get first half of data (AAh) 0236 0048 0030 movwf txbuf ; into the transmit buffer 0237 0049 091C call TX ; and send it 0238 004A 0C55 movlw b’01010101' ; get second half of data (55h) 0239 004B 0030 movwf txbuf ; into transmit buffer 0240 004C 091C call TX ; and send it 0241 ; 0242 004D 0486 bcf port_b,chpsel ; clear the chip select line 0243 ; to initiate write cycle 0244 004E 0000 nop 0245 004F 0586 bsf port_b,chpsel ; set the chip sel line high 0246 ; to begin data polling 0247 0050 0CC8 movlw .200 ; 0248 0051 0035 movwf loops ; poll 100 times before timeout(about 20ms) 0249 0052 0901 polltop call dpdelay ; wait 100us 0250 0053 06E6 btfsc port_b,datout ; is the data out line high? 0251 0054 0A59 goto okpoll ; yes-cycle complete: do another 0252 0055 02F5 decfsz loops ; has it timed out? 8-112

© 1994 Microchip Technology Inc. DS00560D-page 15 Using the 93LC56 and 93LC66 0253 0056 0A52 goto polltop ; no, check again 0254 0057 0525 bsf port_a,timeout; yes, set timeout LED and go on 0255 0058 0A5A goto badpoll ; 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:00 1994 Page 6 Line PC Opcode 0256 0257 0059 0425 okpoll bcf port_a,timeout; clear the timeout LED 0258 005A 0486 badpoll bcf port_b,chpsel ; chip sel line back low 0259 005B 02AC incf addr ; increment address counter 0260 005C 02F3 decfsz bytcnt ; all bytes written? 0261 005D 0A3C goto topwr ; no, do another 0262 ; yes, go on 0263 ; 0264 ; Now continue on to the erase/write disable command 0265 ; 0267 ; EWDS (Erase/Write Disable Routine) 0268 ; This routine executes the erase/write disable command 0269 ; which prevents the contents of the array from being 0270 ; written to. 0271 ;

0273 EWDS

0274 ; 0275 005E 0907 call BSTART ; generate a start bit 0276 ; 0277 005F 0C02 movlw .2 ; set # bits to 2 0278 0060 0032 movwf bits ; 0279 0061 0C00 movlw b’00000000' ; get the opcode (00b) 0280 0062 0030 movwf txbuf ; into the output buffer 0281 0063 091C call TX ; and transmit it 0282 0064 0C08 movlw .8 ; set # bits to 8 0283 0065 0032 movwf bits ; 0284 0066 0C00 movlw b’00000000' ; get opcode and address 0285 ; (00XXXXXX) 0286 0067 0030 movwf txbuf ; into output buffer 0287 0068 091C call TX ; and transmit it 0288 0069 0486 bcf port_b,chpsel ; set chip select line low 0289 006A 0000 nop 0290 006B 0A2B goto EWEN ; start all over 0291 ; 0292 ; 0293 0294 0000 END 8-113

DS00560D-page 16 © 1994 Microchip Technology Inc. Using the 93LC56 and 93LC66 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:20 1994 Page 1 Line PC Opcode 0003 ; 3-Wire Sequential Read Program (93 bytes) 0004 ; 0005 ; This program demonstrates how to interface a 0006 ; Microchip PIC16C54 to a 93LC56 or 93LC66 Serial EE 0007 ; device. This program will read 8 consecutive addresses 0008 ; in the ‘sequential read’ mode. This means that the opcode 0009 ; and address are sent for the first address only. After 0010 ; the first address is read, the Chip Select line is left 0011 ; high and clocks for the remaining 7 bytes are sent to the 0012 ; device. The device will automatically increment the address 0013 ; pointer in this mode, allowing the user to read as many 0014 ; consecutive addresses as needed. This program will repeat 0015 ; forever. 0016 ; 0017 ; This program communicates to the serial EE in the 0018 ; x16 mode, and ASSUMES THE USER HAS SET THE ORG PIN 0019 ; ON THE DEVICE TO Vcc. 0020 ; 0021 ; Timing is based on using the PIC16C54 in ‘XT’ mode 0022 ; using a 4MHz crystal. Clock speeds to the serial EE 0023 ; will be approximately 50 kHz for this setup. 0024 ; 0025 ; PIC16C54 to Serial EE Connections: 0026 ; 0027 ; PIC16C54 Serial EE 0029 ; Pin 10 (RB4) —> Chip Select 0030 ; Pin 11 (RB5) —> Clock 0031 ; Pin 12 (RB6) —> Data In 0032 ; Pin 13 (RB7) —> Data Out 0033 ; ORG = Vcc 0034 ; 0036 ; Register Assignments 0038 0003 status equ 3h ; status register 0039 0005 port_a equ 5h ; port 5 (port_a) 0040 0006 port_b equ 6h ; port 6 (port b) used comm lines to serial EE 0041 000A eeprom equ 0ah ; bit buffer 0042 000C addr equ 0ch ; address register 0043 000D datai equ 0dh ; stored data input reg. 0044 000E datao equ 0eh ; stored data output reg. 0045 0010 txbuf equ 10h ; transmit buffer 0046 0011 count equ 11h ; bits transmitted so far 0047 0012 bits equ 12h ; bits to transmit 0048 0013 bytcnt equ 13h ; byte counter for read routine 0049 0015 loops equ 15h ; delay loop counter 0050 0016 loops2 equ 16h ; delay loop counter 0051 0017 hbyte equ 17h ; high byte for input data 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:20 1994 Page 2 Line PC Opcode 0052 0018 lbyte equ 18h ; low byte for input data 0054 ; Bit Assignments 0056 0007 di equ 7 ; eeprom input 0057 0006 do equ 6 ; eeprom output 0058 0007 datout equ 7 ; data out line (port_b) 0059 0006 datin equ 6 ; data in line (port_b) 0060 0005 sclk equ 5 ; clock line (port_b) 8-114

© 1994 Microchip Technology Inc. DS00560D-page 17 Using the 93LC56 and 93LC66 0061 0004 chpsel equ 4 ; chip select line (port_b) 0062 ; 0064 0000 org 01ffh 0065 01FF 0A40 begin goto PWRUP ; set the reset vector 0066 0000 org 000h 0067 0000 0A40 goto PWRUP 0068 ; 0070 ; DELAY ROUTINE 0071 ; This routine takes the value in ‘loops’ 0072 ; and multiplies it times 1 millisecond to 0073 ; determine delay time.

0075 WAIT

0076 ; 0077 0001 0C6E top movlw .110 ; timing adjustment variable 0078 0002 0036 movwf loops2 0079 0003 0000 top2 nop ; sit and wait 0080 0004 0000 nop 0081 0005 0000 nop 0082 0006 0000 nop 0083 0007 0000 nop 0084 0008 0000 nop 0085 0009 02F6 decfsz loops2 ; inner loops complete? 0086 000A 0A03 goto top2 ; no, go again 0087 ; 0088 000B 02F5 decfsz loops ; outer loops complete? 0089 000C 0A01 goto top ; no, go again 0090 000D 0800 retlw 0 ; yes, return from sub 0091 ; 0093 ; Start Bit Subroutine 0094 ; this routine generates a start bit 0095 ; (Chip select and DI high when clock goes high)

0097 BSTART

0098 000E 04C6 bcf port_b,datin ; set datain and chipselect lines 0099 000F 0486 bcf port_b,chpsel ; low just to check operation 0100 0010 04A6 bcf port_b,sclk ; make sure clock starts low too. 0101 0011 0000 nop 0102 ; 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:20 1994 Page 3 Line PC Opcode 0103 0012 0586 bsf port_b,chpsel ; set chip select line high 0104 0013 05C6 bsf port_b,datin ; set data in line high 0105 0014 0000 nop 0106 0015 05A6 bsf port_b,sclk ; set the clock line high to 0107 ; generate the start bit 0108 0016 0000 nop 0109 0017 0000 nop 0110 0018 04A6 bcf port_b,sclk ; set clock low again 0111 0019 0800 retlw 0 0112 ; 0114 ; BITIN routine reads one bit of data from the 0115 ; serial EE device and stores it in ‘di’

0117 BITIN

0118 001A 05EA bsf eeprom,di ; assume input bit is high 0119 001B 05A6 bsf port_b,sclk ; set clock line high 0120 001C 0000 nop ; 0121 001D 07E6 btfss port_b,datout ; read the data bit 0122 001E 04EA bcf eeprom,di ; input bit was low 0123 001F 04A6 bcf port_b,sclk ; set clock line low 0124 ; 8-115

DS00560D-page 18 © 1994 Microchip Technology Inc. Using the 93LC56 and 93LC66 0125 0020 0800 retlw 0 ; 0126 0128 ; Receive data routine 0129 ; This routine reads one byte of data from the part 0130 ; into the ‘datai’ register. 0132 RX 0133 0021 006D clrf datai ; clear input buffer 0134 0022 0C08 movlw .8 ; set # bits to 8 0135 0023 0031 movwf count 0136 0024 0403 bcf status,0 ; make sure carry bit is low 0137 0025 036D RXLP rlf datai ; rotate the buffer left 1 bit 0138 0026 091A call BITIN ; read 1 bit 0139 0027 040D bcf datai,0 ; assume the input bit was low 0140 0028 06EA btfsc eeprom,di ; check the bit 0141 0029 050D bsf datai,0 ; set high if necessary 0142 002A 02F1 decfsz count ; 8 bits done? 0143 002B 0A25 goto RXLP ; no, do another 0144 002C 0800 retlw 0 0145 ; 0147 ; BITOUT routine 0148 ; This routine takes one bit of data in ‘do’ and 0149 ; transmits it to the serial EE device

0151 BITOUT

0152 002D 07CA btfss eeprom,do ; check state of data bit 0153 002E 0A31 goto bitlow ; low, goto bitlow 16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:20 1994 Page 4 Line PC Opcode 0154 002F 05C6 bsf port_b,datin ; high, set datain high 0155 0030 0A32 goto clkout ; and clock it 0156 ; 0157 0031 04C6 bitlow bcf port_b,datin ; output a logic low 0158 0032 05A6 clkout bsf port_b,sclk ; set clock line high 0159 0033 0000 nop 0160 0034 04A6 bcf port_b,sclk ; return clock line low 0161 0035 0800 retlw 0 0162 ; 0164 ; Transmit Data Subroutine 0165 ; This routine takes the byte of data stored in the 0166 ; ‘datao’ register and transmits it to the serial EE device. 0168 TX 0169 0036 0212 movf bits,w ; set the number of bits to xmit 0170 0037 0031 movwf count 0171 ;

0172 TXLP

0173 0038 04CA bcf eeprom,do ; assume bit 7 is low 0174 0039 06F0 btfsc txbuf,7 ; is bit 7 clear? 0175 003A 05CA bsf eeprom,do ; no, set data bit =1 0176 003B 092D call BITOUT ; transmit 1 bit to serial EE 0177 003C 0370 rlf txbuf ; rotate txbuf left 0178 003D 02F1 decfsz count ; all bits done? 0179 003E 0A38 goto TXLP ; no, do another bit 0180 003F 0800 retlw 0 ; yes, jump out 0181 ; 0183 ; POWER-UP ROUTINE 0184 ; This is the program entry point, which in this case simply 0185 ; sets the port_a I/O lines and directs control to the 0186 ; erase/write enable routine.

0188 PWRUP

© 1994 Microchip Technology Inc. DS00560D-page 19 Using the 93LC56 and 93LC66 0189 ; 0190 0040 0C11 movlw b’00010001' 0191 0041 0005 tris port_a ; set RA0 as input, rest output 0192 0042 0065 clrf port_a ; all lines low 0193 0043 0C80 movlw b’10000000' 0194 0044 0006 tris port_b ; set RB7 as input, rest output; 0195 ; 0196 ; Fall through and do the read 0197 ; 0199 ; READ ROUTINE (Sequential read mode) 0200 ; This routine reads 8 consecutive addresses in 0201 ; sequential mode starting at address 0. This 0202 ; program will repeat forever

0204 READ

16c5x/7x Cross-Assembler V4.12 Released Mon Jun 06 10:49:20 1994 Page 5 Line PC Opcode 0205 ; 0206 0045 0C00 movlw .0 ; set starting address to 00 0207 0046 002C movwf addr ; 0208 0047 0C08 movlw .8 ; set number of addresses to 0209 0048 0033 movwf bytcnt ; read as 8 0210 ; 0211 0049 090E call BSTART ; generate the start bit 0212 004A 0C02 movlw .2 ; set # bits to 2 0213 004B 0032 movwf bits ; 0214 004C 0C80 movlw b’10000000' ; get opcode (10b) 0215 004D 0030 movwf txbuf ; into output buffer 0216 004E 0936 call TX ; and transmit it 0217 004F 0C08 movlw .8 ; 0218 0050 0032 movwf bits ; set number of bits to 8 0219 0051 020C movf addr,w ; get the address 0220 0052 0030 movwf txbuf ; into the output buffer 0221 0053 0936 call TX ; and transmit it 0222 0223 0054 0921 rbyte call RX ; read the high byte 0224 0055 020D movf datai,w ; move input data to w 0225 0056 0037 movwf hbyte ; xfer it to high byte 0226 0227 0057 0921 call RX ; read the low byte 0228 0058 020D movf datai,w ; move input data to w 0229 0059 0037 movwf hbyte ; xfer it to low byte 0230 0231 005A 02AC incf addr ; add 1 to the address 0232 005B 02F3 decfsz bytcnt ; have all bytes been read? 0233 005C 0A54 goto rbyte ; no, read another byte 0234 0235 005D 0486 bcf port_b,chpsel ; yes,clear the chip select line 0236 005E 0A45 goto READ ; and start over 0237 0000 END 8-117

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Product Information

AN560 specifications and overview.

Summary

Lowpower 3-wire non-volatile memories 1994 - 2002

Description

Lowpower 3-wire non-volatile memories 1994 - 2002

Source title AN560 Datasheet(PDF) - Microchip Technology

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