MPR03X FREESCALE | Alldatasheet
Document overview
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Technical content
Features
- 8 µA supply current with two electrodes being monitored with 64 ms response time and IRQ enabled
- Compact 2 x 2 x 0.65 mm 8-lead µDFN package
- Supports up to 3 touch pads
- Only one external component needed
- Intelligent touch detection capacity
- 4 µA maximum shutdown current
- 1.71 V to 2.75 V operation
- Threshold based detection with hysteresis 2C interface, with optional IRQ
- Multiple devices in a system allo w for up to 6 electrodes (need MPR032 with second I2C address)
- -40°C to +85°C operating temperature range Implementations
- Switch Replacements
- Touch Pads Typical Applications
- PC Peripherals
- MP3 Players
- Remote Controls
- Mobile Phones
- Lighting Controls
ORDERING INFORMATION
Device Name Temperature Range Case Number Touch Pads I2C Address Shipping MPR031EP -40 °C to +85°C 1944 (8-Pin UDFN) 3-pads 0x4A Bulk MPR031EPR2 -40 °C to +85°C 1944 (8-Pin UDFN) 3-pads 0x4A Tape and Reel MPR032EP -40 °C to +85°C 1944 (8-Pin UDFN) 3-pads 0x4B Bulk MPR032EPR2 -40 °C to +85°C 1944 (8-Pin UDFN) 3-pads 0x4B Tape and Reel MPR031 MPR032 Capacitive Touch Sensor Controller Top View Figure 1. Pin Connections
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1 Device Overview
1.1 Introduction
filtering to detect pad input condition changes due to touch without any processing by the application.
1.2 Internal Block Diagram
Figure 2. Functional Block Diagram
3 Set Source CurrentMirror
10 Bit ADC
2 External Signal Description
2.1 Device Pin Assignment
The package available for the MPR03X is a 2 x 2 mm 8 pin UDFN. The package and pinout is shown in Figure 3. Figure 3. Package Pinouts
2.2 Recommended S ystem Connections
should have a 75 kΩ connected from the pin to GND. This resistor needs to be 1% tolerance. 4.7 kΩ pull-up resistor should be included on the IRQ. interface to communicate with the MPR03X. All of the connections for the MPR03X are shown by the schematic in Figure 4. Figure 4. Recommended System Connections Schematic Table 1. Device Pin Assignment
5 REXT Reference Resistor
6 ELE0 Electrode 0
7 ELE1 Electrode 1
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2.3 Serial Interface
Sensor Controller are detailed in the following sections.
2.3.1 Serial-Addressing
masters on the 2-wire interface, or if the master in a single-master system has an open-drain SCL output. R/W bit, a register address byte, one or more data bytes, and finally a STOP condition. Figure 5. Wire Serial Interface Timing Details
2.3.2 Start and Stop Conditions
Figure 6. Start and Stop Conditions
2.3.3 Bit Transfer
One data bit is transferred during each clock pulse (Figure 7). The data on SDA must remain stable while SCL is high.
Figure 7. Bit Transfer
2.3.4 Acknowledge
is transmitting to the master, the master generates the acknowledge bit, since the master is the recipient. Figure 8. Acknowledge
2.3.5 The Slave Address
is low for a write command and high for a read command. Figure 9. Slave Address recognizes its slave address, it acknowledges and is then ready for continued communication. The MPR031 and MPR032 slave addresses are show in Table 2.
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2.3.6 Message Format for Writing the MPR03X
command byte are data bytes. Figure 10. Command Byte Received selected by the command byte (Figure 11). Figure 11. Command and Single Data Byte Received MPR03X internal registers because the command byte address generally auto-increments (Section 2.4).
2.3.7 Message Format for Reading the MPR03X
the register addressed by the initialized register address. Figure 12. Reading MPR03X
2.3.8 Operation with Multiple Master
to fix this problem. Follow I2C protocol for multiple master configurations.
2.4 Register Address Map
Table 3. Register Address Map
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3 Functional Overview
3.1 Introduction
different ways but the method used in the MPR03X is explained in this chapter.
3.2 Understanding the Basics
with the third electrode input, so using the interrupt output reduces the number of electrode inputs to two. MPR03X's configuration, making trade-offs between noise rejection, touch response time, and power consumption.
3.3 Implementation
configuration of each block will be described. Electrodes can be connected to the MPR03X in two different configurations, one with an IRQ and one without (Figure 13). Figure 13. MPR03X Pad and Interrupt Connection Options
4 Modes of Operation
4.1 Introduction
MPR03X’s operation modes are Stop, Run1, and Run2. Stop mode is the start-up and configuration mode.
4.2 Stop Mode
In Stop mode, the MPR03X does not monitor any of the electrodes. This mode is the lowest power state.
4.2.1 Initial Power Up
mode drawing minimal supply current. The user configurable pin IRQ/ELE2 defaults to being the interrupt output IRQ function. IRQ is reset on power-up, and so defaults to logic high. Since the IRQ is an open-drain output, IRQ will be high impedance.
4.2.2 Stop Mode Usage
Electrode Configuration register to zero. Table 4. Power-Up Register Configurations
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4.3 Run1 Mode
1 or 2 electrodes are selected, the IRQ/ELE2 pin is automatically configured as an open drain interrupt output. When 3 electrodes are selected in Run1 Mode, the IRQ/ELE2 pin becomes the third electrode input, ELE2 (Figure 14). Figure 14. Electrode/Pad Connections in Run Mode
4.4 Run2 Mode
surface of all the touch pads is used as a single pad, increasing the total area of the conductor. When 2 electrodes are selected in Run2 Mode, the IRQ/ELE2 pin is automatically configured as an open drain interrupt output. When 3 electrodes are selected, the IRQ/ELE2 pin becomes the third electrode input, ELE2 (Figure 15). Figure 15. Electrode/Pad Connections in Area Detection Mode
4.5 Electrode Configuration Register
address of the Electrode Configuration Register is 0x44. Figure 16. Electrode Configuration Register
2 ELE1
Table 5. Electrode Configuration Register Field Descriptions 0 Enabled – In this state baseline calibration is enabled. 1 Disabled – In this state baseline calibration is disabled. operate in. This register is ignored when in Stop Mode. 00 Encoding 0 – Run1 Mode is enabled. 01 Encoding 1 – Run2 Mode is enabled. 10 Encoding 2 – Run2 Mode is enabled. 11 Encoding 3 – Run2 Mode is enabled.
0000 Encoding 0 – Stop Mode
0001 Encoding 1 – Run Mode with ELE0 is enabled, ELE1 is disabled, IRQ
0010 Encoding 2 – Run Mode with ELE0 is enabled, ELE1 is enabled, IRQ is
0011 Encoding 3 – Run Mode with ELE0 is enabled, ELE1 is enabled, ELE2 is
1111 Encoding 15 – Run Mode with ELE0 is enabled, ELE1 is enabled, ELE2 is
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5 Output Mechanisms
5.1 Introduction
determine when a touch occurs.
5.2 Touch Status
using the touch threshold and release threshold registers to determine when a pad is considered touched or untouched. Configuration of this system is discussed in Section 9.
5.2.1 Touch Status Register
of the Touch Pad Status Register is 0x02. Figure 17. Touch Status Register Table 6. Touch Pad Status Register Field Descriptions mode. When OCF is set, the MPR03X cannot be put back into a Run mode. 0 – Current is within limits. 1 – Current is above limits. Writing a 1 to this field will clear the OCF. Electrode 2 Status – The Electrode 2 Status bit shows touched or not touched. Electrode 1 Status – The Electrode 1 Status bit shows touched or not touched. Electrode 0 Status – The Electrode 0 Status bit shows touched or not touched.
5.3 Filtered Data
implementation (Section 8.4).
5.3.1 Filtered Data Low Register
Low register is 0x04. The address of the ELE2 Filtered Data Low register is 0x06. Figure 18. Filtered Data Low Register
5.3.2 Filtered Data High Register
High register is 0x05. The address of the ELE2 Filtered Data High register is 0x07. Figure 19. Filtered Data High Register Table 7. Filtered Data Low Register Field Descriptions the 10 bit filtered A/D reading.
00000000 Encoding 0
11111111 Encoding 25576543210
Table 8. Filtered Data High Register Field Descriptions the 10 bit filtered A/D reading.
00 Encoding 0
11 Encoding 3
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5.4 Baseline Values
least two significant bits are removed before the 10-bit value is displayed in the register.
5.4.1 Baseline Value Register
register is 0x1B. The address of the ELE2 Baseline Value register is 0x1C. Figure 20. Filtered Data High Register Table 9. Filtered Data High Register Field Descriptions 00000000 Encoding 0 – The 10 bit baseline value is between 0 and 3. 11111111 Encoding 255 – The 10 bit baseline value is between 1020 and 1023.
Freescale Semiconductor 15 Preliminary
6 Interrupts
6.1 Introduction
The MPR03X has one interrupt output that is triggered on any touch related event. The interrupts trigger on both the up or down motion of a finger as defined by a set of configurable thresholds.
6.2 Triggering an Interrupt
An interrupt is asserted any time data changes in the Touch Status Register (Section 5.2). This means that if an electrode touch or release occurs, an interrupt will alert the application of the change.
6.3 Interrupt Handling
The MPR03X has one interrupt output that is asserted on any touch related event. The interrupts trigger on both the up or down motion of a finger as defined by a set of configurable thresholds as described in Section 9. To service an interrupt, the application must read the Touch Status Register (Section 5.2) and determine the current condition of the system. As soon as an I2C read takes place the MPR03X will release the interrupt.
6.4 IRQ Pin
The IRQ pin is an open-drain latching interrupt output which requires an external pull-up resistor. The pin will latch down based on the conditions in Section 6.2. The pin will de-assert when an I2C transaction reads from the MPR03X.
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7 Theory of Operation
7.1 Introduction
implementation and the configuration will be described in this section.
7.2 Capacitance Measurement
Figure 21. MPR03X Electrode Measurement Charging Pad Capacitance after charging must be in the range that is shown in Figure 22.
Freescale Semiconductor 17 Preliminary The valid operating range of the electrode charging source is 0.7V to (VDD-.7)V. This means that for a given VDD the valid ADC (voltage visible to the digital interface) range is given by , Equation 3 and . Equation 4 These equations are represented in the graph. In the nominal case of VDD = 1.8V the ADC range is shown below in Table 10. Any ADC counts outside of the range shown are invalid and settings must be adjusted to be within this range. If capacitance variation is of importance for an application after the current output, charge time and supply voltage are determined then the following equations can be used. The valid range for capacitance is calculated by using the minimum and maximum ADC values in the capacitance equation. Substituting the low and high ADC equations into the capacitance equation yields the equations for the minimum and maximum capacitance values which are and . Equation 5
7.3 Sensitivity
The sensitivity of the MPR03X is relative to the capacitance range being measured. Given the ADC value, current and time settings capacitance can be calculated, . Equation 6 For a given capacitance the sensitivity can be measured by taking the derivative of this equation. The result of this is the following equation, representing the change in capacitance per one ADC count, where the ADC in the equation represents the current value. Equation 7 This relationship is shown in the following graph by taking the midpoints off all possible ranges by varying the current and time settings. The midpoint is assumed to be 512 for ADC and the nominal supply voltage of 1.8V is used. Table 10. VDD ADChigh ADClow ADCmid 1.8 625.7778 398.2222 512 ()10247. DD low VADC = () ()10247. DD DD high V VADC −= 7.− DD low V TIC TIChigh ADCV TIC DD × ××= 1024 1024 ADCV TI dADC dC DD × ××−=
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Figure 23. Smaller amounts of change indicate increased sensitivity for the capacitance sensor. Some sample values are shown in Table 11. In the above cases, the capacitance is assumed to be in the middle of the range for specific settings. Within the capacitance range the equation is nonlinear, thus the sensitivity is best with the lowest capacitance. This graph shows the sensitivity derivative reading across the valid range of capacitances for a set I, T, and VDD. For simple small electrodes (that are approximately 21 pF) and a nominal 1.8V supply the following graph is representative of this effect. Figure 24. Table 11. pF Sensitivity (pF/ADC count) 10 -0.01953 100 -0.19531 Sensitivity vs. Midpoint Capacitance for VDD =1 . 8V -4.5 -3.5 -2.5 -1.5 -0.5 0 500 1000 1500 2000 2500 Midpoint Capacitance (pF) Sensitivity (pF/ADC Count) dC/dADC @cmid (pF/1 ADC Count) Sensitivity vs. Capacitance for VDD =1 . 8Va n dI= 3 6µAa n dT=. 5µS 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 10 12 14 16 18 20 22 24 26 28 30 Sensitivity (pF/ADC Count) Maximum Minimum C/ADC Capacitance
7.4 Configuration
in the AFE Configuration register (Section 7.4.1). in the Filter Configuration Register (Section 8.3.1).
7.4.1 AFE Configuration Register
taken in the lowest level filter. The address of the AFE Configuration Register is 0x41. Figure 25. AFE Configuration Register Table 12. AFE Configuration Register Field Descriptions taken as input to the first level of filtering.
00 Encoding 0 – Sets samples taken to 6
01 Encoding 1 – Sets samples taken to 10
10 Encoding 2 – Sets samples taken to 18
11 Encoding 3 – Sets samples taken to 34
supply current to be used when charging and discharging an electrode.
000000 Encoding 0 – Disables Electrode Charging
000001 Encoding 1 – Sets the current to 1uA
111111 Encoding 63 – Sets the current to 63uA
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8.1 Introduction
detection. Each level of filtering will be further described in this section.
8.2 First Level
the Filter Configuration Register (Section 8.3.1). period of the first level filter.
8.3 Second Level
Note that the ESI (Electrode Sample Interval) must be configured to accommodate the low power requirements of a system. Thus, the resulting value will affect the period of the second level filter.
8.3.1 Filter Configuration Register
The Filter Configuration register is used to set. The address of the Electrode Configuration Register is 0x43. Figure 26. Filter Configuration Register
8.4 Third Level Filter
a set of registers including the Max Half Delta Register, the Noise Half Delta Register, and the Noise Count Limit.
8.4.1 Max Half Delta Register
Figure 27. Max Half Delta Register Table 13. Filter Configuration Register Field Descriptions of time an electrode charges and discharges.
000 Encoding 0 – Invalid
010 Encoding 2 – Time is set to 1 µs
111 Encoding 7 – Time is set to 32 µs. samples taken for the second level filter.
00 Encoding 0 – Number of samples is set to 4
01 Encoding 1 – Number of samples is set to 6
10 Encoding 2 – Number of samples is set to 10
11 Encoding 3 – Number of samples is set to 18
period between samples used for the second level of filtering.
000 Encoding 0 – Period set to 1 ms
001 Encoding 1 – Period set to 2 ms
111 Encoding 7 – Period set to 128 ms
Table 14. Max Half Delta Register Field Descriptions variation to pass through the third level filter.
000000 DO NOT USE THIS CODE
000001 Encoding 1 – Sets the Max Half Delta to 1
111111 Encoding 63 – Sets the Max Half Delta to 63
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8.4.2 Noise Half Delta Register
Figure 28. Noise Half Delta Register
8.4.3 Noise Count Limit Register
Figure 29. Noise Count Limit Register Table 15. Noise Half Delta Register Field Descriptions non-noise drift is detected.
000001 Encoding 1 – Sets the Noise Half Delta to 1
111111 Encoding 63 – Sets the Noise Half Delta to 63
Table 16. Noise Count Limit Register Field Descriptions greater than the Max Half Delta necessary before it can be determined that it is non-noise.
0000 Encoding 0 – Sets the Noise Count Limit to 1 (every time over Max Half Delta)
0001 Encoding 1 – Sets the Noise Count Limit to 2 consecutive samples over Max Half Delta
1111 Encoding 15 – Sets the Noise Count Limit to 15 consecutive samples over Max Half Delta
9 Touch Detection
9.1 Introduction
The MPR03X uses a threshold based system to determine when touches occur. This section will describe that mechanism.
9.2 Thresholds
Section 8.4), an interrupt is generated (refer to Section 6), and the touch status register (Section 5.2) is updated. a release would be detected. In either case the system will respond by changing the previously mentioned items.
9.2.1 Touch Threshold Register
Figure 30. Touch Threshold Register
9.2.2 Release Threshold Register
Figure 31. Release Threshold Register Table 17. Touch Threshold Register Field Descriptions
11111111 Encoding 255
Table 18. Release Threshold Register Field Descriptions
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This section contains electrical and timing specifications. than maximum-rated voltages to this high-impedance circuit. Normal handling precautions should be used to avoid exposure to static discharge. (HBM), the Machine Model (MM) and the Charge Device Model (CDM). temperature, unless specified otherwise in the device specification. Table 19. Absolute Maximum Ratings - Voltage (with respect to VSS) Table 20. ESD and Latch-up Test Conditions
This section includes information about power supply requirements and I/O pin characteristics.
- Parameters tested 100% at final test at room temperature; limits at -40°C and +85°C verified by characterization, not tested in production
- Limits verified by characterization, not tested in production
- Parameters tested 100% at final test at room temperature; limits at -40°C and +70°C verified by characterization, not tested in production
- Limits verified by characterization, not tested in production.
Table 21. DC Characteristics (Temperature Range = –40°C to 85°C Ambient) Table 22. AC CHARACTERISTICS
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This section includes information about I2C AC Characteristics. Table 23. I2C AC Characteristics
Freescale Semiconductor 27 Preliminary Appendix B Brief Register Descriptions REGISTER Abrv Fields REGISTER ADDRESS Initial Value Touch Status Register TS OCF E2S E1S E0S 0x00 0x00 ELE0 Filtered Data Low Register E0FDL E0FDLB 0x02 0x00 ELE0 Filtered Data High Register E0FDH E0FDHB 0x03 0x00 ELE1 Filtered Data Low Register E1FDL E1FDLB 0x04 0x00 ELE1 Filtered Data High Register E1FDH E1FDHB 0x05 0x00 ELE2 Filtered Data Low Register E2FDL E2FDLB 0x06 0x00 ELE2 Filtered Data High Register D2FDH E2FDHB 0x07 0x00 ELE0 Baseline Value Register E0BV E0BV 0x1A 0x00 ELE1 Baseline Value Register E1BV E1BV 0x1B 0x00 ELE2 Baseline Value Register E2BV E2BV 0x1C 0x00 Max Half Delta Register MHD MHD 0x26 0x00 Noise Half Delta Register NHD NHD 0x27 0x00 Noise Count Limit Register NCL NCL 0x28 0x00 ELE0 Touch Threshold Register E0TTH E0TTH 0x29 0x00 ELE0 Release Threshold Register E0RTH E0RTH 0x2A 0x00 ELE1 Touch Threshold Register E1TTH E1TTH 0x2B 0x00 ELE1 Release Threshold Register E1RTH E1RTH 0x2C 0x00 ELE2 Touch Threshold Register E2TTH E2TTH 0x2D 0x00 ELE2 Release Threshold Register E2RTH E2RTH 0x2E 0x00 AFE Configuration Register AFEC FFI CDC 0x41 0x08 Filter Configuration Register FC CDT SFI ESI 0x43 0x04 Electrode Configuration Register EC CalL ock ModeSel EleEn 0x44 0x00
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Appendix C Order ing Information C.1 Ordering Information This section contains ordering information for MPR03X devices. C.2 Device Numbering Scheme All Proximity Sensor Products have a similar numbering scheme. The below diagram explains what each part number in the family represents. Device Name Temperature Range Case Number Touch Pads I2C Address Shipping MPR031EP -40 °C to +85°C 1944 (8-Pin UDFN) 3-pads 0x4A Bulk MPR031EPR2 -40 °C to +85°C 1944 (8-Pin UDFN) 3-pads 0x4A Tape and Reel MPR032EP -40 °C to +85°C 1944 (8-Pin UDFN) 3-pads 0x4B Bulk MPR032EPR2 -40 °C to +85°C 1944 (8-Pin UDFN) 3-pads 0x4B Tape and Reel M Status (M = Fully Qualified, P = Preproduction) PR Proximity Sensor Product EE X P Number of Electrodes (03 = 3 electrode device) Package Designator Version (Q = QFN, EJ = TSSOP , EP = µDFN)
Freescale Semiconductor 29 Preliminary PACKAGE DIMENSIONS PAGE 1 OF 3
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Freescale Semiconductor 31 Preliminary PAGE 3 OF 3
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