Sam Grove / MPR121

A device driver for the Freescale MPR121 capactive touch IC. Not optimized for any particular system, just a starting point to get the chip up in running in no time. Changes to registers init() method will tailor the library for end system use.

Dependents:   Seeed_Grove_I2C_Touch_Example MPR121_HelloWorld mbed_petbottle_holder_shikake test_DEV-10508 ... more

Datasheet:

http://cache.freescale.com/files/sensors/doc/data_sheet/MPR121.pdf

Information

Must add pull-ups to the I2C bus!!

MPR121.cpp@5:3934358ec2b7, 2014-08-15 (annotated)

Committer:
sam_grove
Date:
Fri Aug 15 23:00:13 2014 +0000
Revision:
5:3934358ec2b7
Parent:
3:828260f21de6
Child:
6:b6bb38744edd
Updated library to work without the IRQ pin being connected

Who changed what in which revision?

UserRevisionLine numberNew contents of line
sam_grove 0:42add775212a 1 /**
sam_grove 0:42add775212a 2 * @file MPR121.cpp
sam_grove 0:42add775212a 3 * @brief Device driver - MPR121 capactiive touch IC
sam_grove 0:42add775212a 4 * @author sam grove
sam_grove 0:42add775212a 5 * @version 1.0
sam_grove 0:42add775212a 6 * @see http://cache.freescale.com/files/sensors/doc/data_sheet/MPR121.pdf
sam_grove 0:42add775212a 7 *
sam_grove 0:42add775212a 8 * Copyright (c) 2013
sam_grove 0:42add775212a 9 *
sam_grove 0:42add775212a 10 * Licensed under the Apache License, Version 2.0 (the "License");
sam_grove 0:42add775212a 11 * you may not use this file except in compliance with the License.
sam_grove 0:42add775212a 12 * You may obtain a copy of the License at
sam_grove 0:42add775212a 13 *
sam_grove 0:42add775212a 14 * http://www.apache.org/licenses/LICENSE-2.0
sam_grove 0:42add775212a 15 *
sam_grove 0:42add775212a 16 * Unless required by applicable law or agreed to in writing, software
sam_grove 0:42add775212a 17 * distributed under the License is distributed on an "AS IS" BASIS,
sam_grove 0:42add775212a 18 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
sam_grove 0:42add775212a 19 * See the License for the specific language governing permissions and
sam_grove 0:42add775212a 20 * limitations under the License.
sam_grove 0:42add775212a 21 */
sam_grove 0:42add775212a 22
sam_grove 0:42add775212a 23 #include "MPR121.h"
sam_grove 3:828260f21de6 24 #include "mbed_debug.h"
sam_grove 3:828260f21de6 25
sam_grove 3:828260f21de6 26 #define DEBUG 1
sam_grove 5:3934358ec2b7 27
sam_grove 0:42add775212a 28 MPR121::MPR121(I2C &i2c, InterruptIn &pin, MPR121_ADDR i2c_addr)
sam_grove 0:42add775212a 29 {
sam_grove 0:42add775212a 30 _i2c = &i2c;
sam_grove 0:42add775212a 31 _irq = &pin;
sam_grove 0:42add775212a 32 _i2c_addr = (i2c_addr << 1);
sam_grove 5:3934358ec2b7 33
sam_grove 5:3934358ec2b7 34 return;
sam_grove 5:3934358ec2b7 35 }
sam_grove 5:3934358ec2b7 36
sam_grove 5:3934358ec2b7 37 MPR121::MPR121(I2C &i2c, MPR121_ADDR i2c_addr)
sam_grove 5:3934358ec2b7 38 {
sam_grove 5:3934358ec2b7 39 _i2c = &i2c;
sam_grove 5:3934358ec2b7 40 _irq = NULL;
sam_grove 5:3934358ec2b7 41 _i2c_addr = (i2c_addr << 1);
sam_grove 5:3934358ec2b7 42
sam_grove 0:42add775212a 43 return;
sam_grove 0:42add775212a 44 }
sam_grove 0:42add775212a 45
sam_grove 0:42add775212a 46 void MPR121::init(void)
sam_grove 0:42add775212a 47 {
sam_grove 0:42add775212a 48 // set the i2c speed
sam_grove 0:42add775212a 49 _i2c->frequency(400000);
sam_grove 0:42add775212a 50 // irq is open-collector and active-low
sam_grove 5:3934358ec2b7 51 if(_irq != NULL) {
sam_grove 5:3934358ec2b7 52 _irq->mode(PullUp);
sam_grove 5:3934358ec2b7 53 }
sam_grove 5:3934358ec2b7 54
sam_grove 0:42add775212a 55 // setup and registers - start with POR values (must be in stop mode)
sam_grove 0:42add775212a 56 MPR121::writeRegister(SRST, 0x63); //REG 0x80
sam_grove 5:3934358ec2b7 57
sam_grove 0:42add775212a 58 // Baseline Filtering Control Register (changes response sensitivity)
sam_grove 0:42add775212a 59 // http://cache.freescale.com/files/sensors/doc/app_note/AN3891.pdf
sam_grove 0:42add775212a 60 MPR121::writeRegister(MHDR, 0x1); //REG 0x2B
sam_grove 0:42add775212a 61 MPR121::writeRegister(NHDR, 0x1); //REG 0x2C
sam_grove 0:42add775212a 62 MPR121::writeRegister(NCLR, 0x0); //REG 0x2D
sam_grove 0:42add775212a 63 MPR121::writeRegister(FDLR, 0x0); //REG 0x2E
sam_grove 0:42add775212a 64 MPR121::writeRegister(MHDF, 0x1); //REG 0x2F
sam_grove 0:42add775212a 65 MPR121::writeRegister(NHDF, 0x1); //REG 0x30
sam_grove 0:42add775212a 66 MPR121::writeRegister(NCLF, 0xFF); //REG 0x31
sam_grove 0:42add775212a 67 MPR121::writeRegister(FDLF, 0x2); //REG 0x32
sam_grove 5:3934358ec2b7 68
sam_grove 0:42add775212a 69 // Touch / Release Threshold
sam_grove 0:42add775212a 70 // cache.freescale.com/files/sensors/doc/app_note/AN3892.pdf
sam_grove 5:3934358ec2b7 71 for(int i=0; i<(12*2); i+=2) { // touch
sam_grove 3:828260f21de6 72 MPR121::writeRegister(static_cast<MPR121_REGISTER>(E0TTH+i), 0x20); //REG 0x41...0x58 odd
sam_grove 0:42add775212a 73 }
sam_grove 5:3934358ec2b7 74 for(int i=0; i<(12*2); i+=2) { // release
sam_grove 3:828260f21de6 75 MPR121::writeRegister(static_cast<MPR121_REGISTER>(E0RTH+i), 0x10); //REG 0x41...0x58 even
sam_grove 0:42add775212a 76 }
sam_grove 5:3934358ec2b7 77
sam_grove 0:42add775212a 78 // Debounce Register DR=b6...4, DT=b2...0
sam_grove 0:42add775212a 79 MPR121::writeRegister(DT_DR, 0x11); //REG 0x5B
sam_grove 5:3934358ec2b7 80
sam_grove 0:42add775212a 81 // Filter and Global CDC CDT Configuration (sample time, charge current)
sam_grove 0:42add775212a 82 MPR121::writeRegister(CDC_CONFIG, 0x10); //REG 0x5C default 10
sam_grove 0:42add775212a 83 MPR121::writeRegister(CDT_CONFIG, 0x20); //REG 0x5D default 24
sam_grove 5:3934358ec2b7 84
sam_grove 0:42add775212a 85 // Auto-Configuration Registers
sam_grove 0:42add775212a 86 // http://cache.freescale.com/files/sensors/doc/app_note/AN3889.pdf
sam_grove 0:42add775212a 87 MPR121::writeRegister(AUTO_CFG0, 0x33); // REG 0x7B
sam_grove 0:42add775212a 88 MPR121::writeRegister(AUTO_CFG1, 0x07); // REG 0x7C
sam_grove 0:42add775212a 89 MPR121::writeRegister(USL, 0xc9); // REG 0x7D((3.3-.07)/3.3) * 256
sam_grove 0:42add775212a 90 MPR121::writeRegister(LSL, 0x83); // REG 0x7E((3.3-.07)/3.3) * 256 * 0.65f
sam_grove 0:42add775212a 91 MPR121::writeRegister(TL, 0xb5); // REG 0x7F((3.3-.07)/3.3) * 256 * 0.9f
sam_grove 0:42add775212a 92 // 255 > USL > TL > LSL > 0
sam_grove 5:3934358ec2b7 93
sam_grove 0:42add775212a 94 // Electrode Configuration Register - enable all 12 and start
sam_grove 0:42add775212a 95 MPR121::writeRegister(ECR, 0x8f);
sam_grove 5:3934358ec2b7 96
sam_grove 0:42add775212a 97 return;
sam_grove 0:42add775212a 98 }
sam_grove 0:42add775212a 99
sam_grove 0:42add775212a 100 void MPR121::enable(void)
sam_grove 0:42add775212a 101 {
sam_grove 0:42add775212a 102 _button = 0;
sam_grove 0:42add775212a 103 _button_has_changed = 0;
sam_grove 1:cee45334b36a 104 // enable the 12 electrodes - allow disable to put device into
sam_grove 1:cee45334b36a 105 // lower current consumption mode
sam_grove 1:cee45334b36a 106 MPR121::writeRegister(ECR, 0x8f);
sam_grove 1:cee45334b36a 107 // and attach the interrupt handler
sam_grove 5:3934358ec2b7 108 if(_irq != NULL) {
sam_grove 5:3934358ec2b7 109 _irq->fall(this, &MPR121::handler);
sam_grove 5:3934358ec2b7 110 }
sam_grove 5:3934358ec2b7 111
sam_grove 0:42add775212a 112 return;
sam_grove 0:42add775212a 113 }
sam_grove 0:42add775212a 114
sam_grove 0:42add775212a 115 void MPR121::disable(void)
sam_grove 0:42add775212a 116 {
sam_grove 1:cee45334b36a 117 // detach the interrupt handler
sam_grove 0:42add775212a 118 _irq->fall(NULL);
sam_grove 0:42add775212a 119 _button = 0;
sam_grove 0:42add775212a 120 _button_has_changed = 0;
sam_grove 1:cee45334b36a 121 // put the device in low current consumption mode - dont re-init registers
sam_grove 1:cee45334b36a 122 MPR121::writeRegister(ECR, 0x0);
sam_grove 1:cee45334b36a 123 MPR121::writeRegister(AUTO_CFG0, 0x0); // REG 0x7B
sam_grove 1:cee45334b36a 124 MPR121::writeRegister(AUTO_CFG1, 0x0); // REG 0x7C
sam_grove 5:3934358ec2b7 125
sam_grove 0:42add775212a 126 return;
sam_grove 0:42add775212a 127 }
sam_grove 0:42add775212a 128
sam_grove 0:42add775212a 129 uint32_t MPR121::isPressed(void)
sam_grove 0:42add775212a 130 {
sam_grove 0:42add775212a 131 return _button_has_changed;
sam_grove 0:42add775212a 132 }
sam_grove 0:42add775212a 133
sam_grove 0:42add775212a 134 uint16_t MPR121::buttonPressed(void)
sam_grove 0:42add775212a 135 {
sam_grove 5:3934358ec2b7 136 if(_irq == NULL) {
sam_grove 5:3934358ec2b7 137 handler();
sam_grove 5:3934358ec2b7 138 }
sam_grove 0:42add775212a 139 _button_has_changed = 0;
sam_grove 0:42add775212a 140 return _button;
sam_grove 0:42add775212a 141 }
sam_grove 0:42add775212a 142
sam_grove 3:828260f21de6 143 void MPR121::registerDump(Serial &obj) const
sam_grove 0:42add775212a 144 {
sam_grove 0:42add775212a 145 uint8_t reg_val = 0;
sam_grove 5:3934358ec2b7 146
sam_grove 5:3934358ec2b7 147 for(int i=0; i<0x80; i++) {
sam_grove 3:828260f21de6 148 reg_val = MPR121::readRegister(static_cast<MPR121_REGISTER>(i));
sam_grove 3:828260f21de6 149 obj.printf("Reg 0x%02x: 0x%02x \n", i, reg_val);
sam_grove 0:42add775212a 150 }
sam_grove 5:3934358ec2b7 151
sam_grove 5:3934358ec2b7 152 return;
sam_grove 5:3934358ec2b7 153 }
sam_grove 5:3934358ec2b7 154
sam_grove 5:3934358ec2b7 155 void MPR121::registerDump(void) const
sam_grove 5:3934358ec2b7 156 {
sam_grove 5:3934358ec2b7 157 uint8_t reg_val = 0;
sam_grove 5:3934358ec2b7 158
sam_grove 5:3934358ec2b7 159 for(int i=0; i<0x80; i++) {
sam_grove 5:3934358ec2b7 160 reg_val = MPR121::readRegister(static_cast<MPR121_REGISTER>(i));
sam_grove 5:3934358ec2b7 161 printf("Reg 0x%02x: 0x%02x \n", i, reg_val);
sam_grove 5:3934358ec2b7 162 }
sam_grove 5:3934358ec2b7 163
sam_grove 0:42add775212a 164 return;
sam_grove 0:42add775212a 165 }
sam_grove 0:42add775212a 166
sam_grove 0:42add775212a 167 void MPR121::handler(void)
sam_grove 0:42add775212a 168 {
sam_grove 0:42add775212a 169 uint16_t reg_val = 0, oor_val = 0;
sam_grove 0:42add775212a 170 // read register 0 and 1
sam_grove 0:42add775212a 171 reg_val = MPR121::readRegister(ELE0_7_STAT);
sam_grove 0:42add775212a 172 reg_val |= MPR121::readRegister(ELE8_11_STAT) << 8;
sam_grove 0:42add775212a 173 // 2 and 3
sam_grove 0:42add775212a 174 oor_val = MPR121::readRegister(ELE0_7_OOR_STAT);
sam_grove 0:42add775212a 175 oor_val |= MPR121::readRegister(ELE8_11_OOR_STAT) << 8;
sam_grove 5:3934358ec2b7 176
sam_grove 3:828260f21de6 177 // debugging stuff and errors - if OOR fails someone was touching the pad during auto-config
sam_grove 3:828260f21de6 178 // Just reboot until they're not doing this
sam_grove 5:3934358ec2b7 179 if((0 != oor_val) && DEBUG) {
sam_grove 3:828260f21de6 180 debug("MPR121 OOR failure - 0x%04x\n", oor_val);
sam_grove 3:828260f21de6 181 wait(0.1f);
sam_grove 3:828260f21de6 182 NVIC_SystemReset();
sam_grove 0:42add775212a 183 }
sam_grove 5:3934358ec2b7 184
sam_grove 0:42add775212a 185 _button = reg_val;
sam_grove 0:42add775212a 186 _button_has_changed = 1;
sam_grove 5:3934358ec2b7 187
sam_grove 0:42add775212a 188 return;
sam_grove 0:42add775212a 189 }
sam_grove 0:42add775212a 190
sam_grove 3:828260f21de6 191 void MPR121::writeRegister(MPR121_REGISTER const reg, uint8_t const data) const
sam_grove 0:42add775212a 192 {
sam_grove 0:42add775212a 193 char buf[2] = {reg, data};
sam_grove 0:42add775212a 194 uint8_t result = 0;
sam_grove 5:3934358ec2b7 195
sam_grove 0:42add775212a 196 result = _i2c->write(_i2c_addr, buf, 2);
sam_grove 5:3934358ec2b7 197
sam_grove 5:3934358ec2b7 198 if(result && DEBUG) {
sam_grove 3:828260f21de6 199 debug("I2c write failed\n");
sam_grove 0:42add775212a 200 }
sam_grove 5:3934358ec2b7 201
sam_grove 0:42add775212a 202 return;
sam_grove 0:42add775212a 203 }
sam_grove 0:42add775212a 204
sam_grove 3:828260f21de6 205 uint8_t MPR121::readRegister(MPR121_REGISTER const reg) const
sam_grove 0:42add775212a 206 {
sam_grove 3:828260f21de6 207 char buf[1] = {reg}, data = 0;
sam_grove 3:828260f21de6 208 uint8_t result = 1;
sam_grove 5:3934358ec2b7 209
sam_grove 3:828260f21de6 210 result &= _i2c->write(_i2c_addr, buf, 1, true);
sam_grove 5:3934358ec2b7 211 result &= _i2c->read(_i2c_addr, &data, 1);
sam_grove 5:3934358ec2b7 212
sam_grove 5:3934358ec2b7 213 if(result && DEBUG) {
sam_grove 3:828260f21de6 214 debug("I2c read failed\n");
sam_grove 0:42add775212a 215 }
sam_grove 5:3934358ec2b7 216
sam_grove 0:42add775212a 217 return data;
sam_grove 0:42add775212a 218 }