Diff: MicroBitMpr121.cpp

Revision:

0:fb4572fc4901

Child:

1:f6fed00a3ff2

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MicroBitMpr121.cpp	Mon Jan 16 08:46:27 2017 +0000
@@ -0,0 +1,196 @@
+/**
+ * @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 "MicroBit.h"
+#include "microbit-mpr121-pi-cap.h"
+#include "mbed_debug.h"
+
+#define DEBUG 1
+    
+MicroBitMpr121::MicroBitMpr121(I2C &i2c, InterruptIn &pin, MPR121_ADDR i2c_addr)
+{
+    _i2c = &i2c;
+    _irq = &pin;
+    _i2c_addr = (i2c_addr << 1);
+    
+    return;
+}
+
+void MPR121::init(void)
+{
+    // 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 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(int i=0; i<(12*2); i+=2) // touch
+    {
+        MPR121::writeRegister(static_cast<MPR121_REGISTER>(E0TTH+i), 0x20); //REG 0x41...0x58 odd
+    }
+    for(int i=0; i<(12*2); i+=2) // release
+    {
+        MPR121::writeRegister(static_cast<MPR121_REGISTER>(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
+    
+    // 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
+    
+    // Electrode Configuration Register - enable all 12 and start
+    MPR121::writeRegister(ECR, 0x8f);
+    
+    return;
+}
+
+void MPR121::enable(void)
+{
+    _button = 0;
+    _button_has_changed = 0;
+    // enable the 12 electrodes - allow disable to put device into
+    //  lower current consumption mode
+    MPR121::writeRegister(ECR, 0x8f);
+    // and attach the interrupt handler
+    _irq->fall(this, &MPR121::handler);
+    
+    return;
+}
+
+void MPR121::disable(void)
+{
+    // detach the interrupt handler
+    _irq->fall(NULL);
+    _button = 0;
+    _button_has_changed = 0;
+    //  put the device in low current consumption mode - dont re-init registers
+    MPR121::writeRegister(ECR, 0x0);
+    MPR121::writeRegister(AUTO_CFG0, 0x0); // REG 0x7B
+    MPR121::writeRegister(AUTO_CFG1, 0x0); // REG 0x7C
+    
+    return;
+}
+
+uint32_t MPR121::isPressed(void)
+{
+    return _button_has_changed;
+}
+
+uint16_t MPR121::buttonPressed(void)
+{
+    _button_has_changed = 0;
+    return _button;
+}
+
+void MPR121::registerDump(Serial &obj) const
+{
+    uint8_t reg_val = 0;
+    
+    for(int i=0; i<0x80; i++)
+    {
+        reg_val = MPR121::readRegister(static_cast<MPR121_REGISTER>(i));
+        obj.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;
+    
+    // debugging stuff and errors - if OOR fails someone was touching the pad during auto-config
+    //  Just reboot until they're not doing this
+    if((0 != oor_val) && DEBUG)
+    {
+        debug("MPR121 OOR failure - 0x%04x\n", oor_val);
+        wait(0.1f);
+        NVIC_SystemReset();
+    }
+   
+    _button = reg_val;
+    _button_has_changed = 1;
+    
+    return;
+}
+
+void MPR121::writeRegister(MPR121_REGISTER const reg, uint8_t const data) const
+{
+    char buf[2] = {reg, data};
+    uint8_t result = 0;
+    
+    result = _i2c->write(_i2c_addr, buf, 2);
+    
+    if(result && DEBUG)
+    {
+        debug("I2c write failed\n");
+    }
+    
+    return;
+}
+
+uint8_t MPR121::readRegister(MPR121_REGISTER const reg) const
+{
+    char buf[1] = {reg}, data = 0;
+    uint8_t result = 1;
+    
+    result &= _i2c->write(_i2c_addr, buf, 1, true);
+    result &= _i2c->read(_i2c_addr, &data, 1); 
+    
+    if(result && DEBUG)
+    {
+        debug("I2c read failed\n");
+    }
+    
+    return data;
+}