Diff: MPR121.cpp

Revision:

0:42add775212a

Child:

1:cee45334b36a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MPR121.cpp	Thu Mar 07 19:25:08 2013 +0000
@@ -0,0 +1,210 @@
+/**
+ * @file    MPR121.cpp
+ * @brief   Device driver - MPR121 capactiive touch IC
+ * @author  sam grove
+ * @version 1.0
+ * @see     http://cache.freescale.com/files/sensors/doc/data_sheet/MPR121.pdf
+ *
+ * Copyright (c) 2013
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "MPR121.h"
+    
+MPR121::MPR121(I2C &i2c, InterruptIn &pin, MPR121_ADDR i2c_addr)
+{
+    _i2c = &i2c;
+    _irq = &pin;
+    _i2c_addr = (i2c_addr << 1);
+    
+    return;
+}
+
+void MPR121::init(void)
+{
+    uint8_t i = 0;
+    // set the i2c speed
+    _i2c->frequency(400000);
+    // irq is open-collector and active-low
+    _irq->mode(PullUp);
+    
+    // setup and registers - start with POR values (must be in stop mode)
+    MPR121::writeRegister(SRST, 0x63); //REG 0x80
+    
+    // baseline < filtered data = touch (set by auto-config)
+//    for(i=0; i<12; i++)
+//    {
+//        MPR121::writeRegister(E0BV+i, 0x10); //REG 0x1E...0x29
+//    }
+    
+    // Baseline Filtering Control Register (changes response sensitivity)
+    // http://cache.freescale.com/files/sensors/doc/app_note/AN3891.pdf
+    MPR121::writeRegister(MHDR, 0x1);  //REG 0x2B
+    MPR121::writeRegister(NHDR, 0x1);  //REG 0x2C
+    MPR121::writeRegister(NCLR, 0x0);  //REG 0x2D
+    MPR121::writeRegister(FDLR, 0x0);  //REG 0x2E
+    MPR121::writeRegister(MHDF, 0x1);  //REG 0x2F
+    MPR121::writeRegister(NHDF, 0x1);  //REG 0x30
+    MPR121::writeRegister(NCLF, 0xFF); //REG 0x31
+    MPR121::writeRegister(FDLF, 0x2);  //REG 0x32
+    
+    
+    // Touch / Release Threshold
+    // cache.freescale.com/files/sensors/doc/app_note/AN3892.pdf
+    for(i=0; i<(12*2); i+=2) // touch
+    {
+        MPR121::writeRegister(E0TTH+i, 0x20); //REG 0x41...0x58 odd
+    }
+    for(i=0; i<(12*2); i+=2) // release
+    {
+        MPR121::writeRegister(E0RTH+i, 0x10); //REG 0x41...0x58 even
+    }
+    
+    // Debounce Register DR=b6...4, DT=b2...0
+    MPR121::writeRegister(DT_DR, 0x11); //REG 0x5B
+    
+    // Filter and Global CDC CDT Configuration (sample time, charge current)
+    MPR121::writeRegister(CDC_CONFIG, 0x10); //REG 0x5C default 10
+    MPR121::writeRegister(CDT_CONFIG, 0x20); //REG 0x5D default 24
+    
+    // Electrode Charge Current Register - uses CDC_STAT if 0
+//    for(i=0; i<12; i++) // current
+//    {
+//        MPR121::writeRegister(CDC0+i, 0x10); //REG 0x5F ... 0x6B
+//    }
+//    for(i=0; i<6; i++) // time
+//    {
+//        MPR121::writeRegister(CDT0_CDT1+i, 0x11); //REG 0x6C ... 0x72
+//    }
+    
+    // Auto-Configuration Registers
+    // http://cache.freescale.com/files/sensors/doc/app_note/AN3889.pdf
+    MPR121::writeRegister(AUTO_CFG0, 0x33); // REG 0x7B
+    MPR121::writeRegister(AUTO_CFG1, 0x07); // REG 0x7C
+    MPR121::writeRegister(USL, 0xc9);       // REG 0x7D((3.3-.07)/3.3) * 256
+    MPR121::writeRegister(LSL, 0x83);       // REG 0x7E((3.3-.07)/3.3) * 256 * 0.65f
+    MPR121::writeRegister(TL,  0xb5);       // REG 0x7F((3.3-.07)/3.3) * 256 * 0.9f
+    // 255 > USL > TL > LSL > 0
+    
+//    MPR121::registerDump();
+    
+    // Electrode Configuration Register - enable all 12 and start
+    MPR121::writeRegister(ECR, 0x8f);
+    
+    return;
+}
+
+void MPR121::enable(void)
+{
+    _button = 0;
+    _button_has_changed = 0;
+    _irq->fall(this, &MPR121::handler);
+    
+    return;
+}
+
+void MPR121::disable(void)
+{
+    _irq->fall(NULL);
+    _button = 0;
+    _button_has_changed = 0;
+    
+    return;
+}
+
+uint32_t MPR121::isPressed(void)
+{
+    return _button_has_changed;
+}
+
+uint16_t MPR121::buttonPressed(void)
+{
+    _button_has_changed = 0;
+    return _button;
+}
+
+void MPR121::registerDump(void)
+{
+    uint8_t reg_val = 0;
+    
+    for(int i=0; i<0x80; i++)
+    {
+        reg_val = MPR121::readRegister(i);
+        printf("Reg 0x%02x: 0x%02x \n", i, reg_val);
+    }
+    
+    return;
+}
+
+void MPR121::handler(void)
+{
+    uint16_t reg_val = 0, oor_val = 0;
+    // read register 0 and 1
+    reg_val  = MPR121::readRegister(ELE0_7_STAT);
+    reg_val |= MPR121::readRegister(ELE8_11_STAT) << 8;
+    // 2 and 3
+    oor_val  = MPR121::readRegister(ELE0_7_OOR_STAT);
+    oor_val |= MPR121::readRegister(ELE8_11_OOR_STAT) << 8;
+    
+    if(0 != oor_val)
+    {
+        error("%s %d: MPR121 OOR failure - 0x%04x\n", __FILE__, __LINE__, oor_val);
+    }
+   
+    _button = reg_val;
+    _button_has_changed = 1;
+    
+    return;
+}
+
+void MPR121::writeRegister(uint8_t reg, uint8_t data)
+{
+    char buf[2] = {reg, data};
+    uint8_t result = 0;
+    
+    __disable_irq(); // Tickers and other timebase events can jack up the I2C bus
+    result = _i2c->write(_i2c_addr, buf, 2);
+    __enable_irq();  // Just need to block during the transaction
+    
+    if(0 != result)
+    {
+        error("%s %d: I2c write failed\n", __FILE__, __LINE__);
+    }
+    
+    return;
+}
+
+uint8_t MPR121::readRegister(uint8_t reg)
+{
+    uint8_t result = 1, data = 0;
+    
+    __disable_irq(); // Tickers and other timebase events can jack up the I2C bus
+    _i2c->start();
+    result &= _i2c->write(_i2c_addr);
+    result &= _i2c->write(reg);
+    // issue a repeated start...
+    _i2c->start();
+    result &= _i2c->write(_i2c_addr | 0x01);
+    // read with nak
+    data = _i2c->read(0);
+    _i2c->stop();
+    __enable_irq();  // Just need to block during the transaction
+    
+    if(1 != result)
+    {
+        error("%s %d: I2C read failed\n", __FILE__, __LINE__);
+    }
+    
+    return data;
+}