mpr121: Initial implementation

This module implements support for the Grove I2C touch sensor
(mpr121).

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Zion Orent <zorent@ics.com>
Signed-off-by: John Van Drasek <john.r.van.drasek@intel.com>

src/mpr121/CMakeLists.txt

@@ -0,0 +1,5 @@
+set (libname "mpr121")
+set (libdescription "upm mpr121 I2C Touch module")
+set (module_src ${libname}.cxx)
+set (module_h ${libname}.h)
+upm_module_init()

src/mpr121/jsupm_mpr121.i

@@ -0,0 +1,8 @@
+%module jsupm_mpr121
+%include "../upm.i"
+
+%{
+    #include "mpr121.h"
+%}
+
+%include "mpr121.h"

src/mpr121/mpr121.cxx

@@ -0,0 +1,204 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <iostream>
+#include <string>
+
+#include "mpr121.h"
+
+using namespace upm;
+using namespace std;
+
+
+MPR121::MPR121(int bus, uint8_t address)
+{
+  // setup our i2c link
+  m_i2c = mraa_i2c_init(bus);
+
+  m_addr = address;
+
+  mraa_result_t ret = mraa_i2c_address(m_i2c, m_addr);
+
+  if (ret != MRAA_SUCCESS) 
+    cerr << "MPR121: Could not initialize i2c bus. " << endl;
+
+  m_buttonStates = 0;
+  m_overCurrentFault = false;
+}
+
+MPR121::~MPR121()
+{
+  mraa_i2c_stop(m_i2c);
+}
+
+mraa_result_t MPR121::writeBytes(uint8_t reg, uint8_t *buffer, unsigned int len)
+{
+  if (!len || !buffer)
+    return MRAA_SUCCESS;
+
+  // create a buffer 1 byte larger than the supplied buffer,
+  // store the register in the first byte
+  uint8_t buf2[len + 1];
+
+  buf2[0] = reg;
+
+  // copy in the buffer after the reg byte
+  for (int i=1; i<(len + 1); i++)
+    buf2[i] = buffer[i-1];
+
+  mraa_i2c_address(m_i2c, m_addr);
+
+  return mraa_i2c_write(m_i2c, buf2, len + 1);
+}
+
+void MPR121::readBytes(uint8_t reg, uint8_t *buffer, unsigned int len)
+{
+  if (!len || !buffer)
+    return;
+
+  // The usual mraa_i2c_read() does not work here, so we need to
+  // read each byte individually.
+  for (int i=0; i<len; i++)
+    buffer[i] = mraa_i2c_read_byte_data(m_i2c, reg + i);
+
+  return;
+}
+
+bool MPR121::configAN3944()
+{
+  // Configure the mpr121 chip as recommended in the AN3944 MPR121
+  // Quick Start Guide
+
+  mraa_result_t rv;
+
+  // First, turn off all electrodes by zeroing out the Electrode Configuration
+  // register.
+  // If this one fails, it's unlikely any of the others will succeed.
+  uint8_t eleConf = 0x00;
+  if ((rv = writeBytes(0x5e, &eleConf, 1)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
+      return false;
+    }
+
+  // Section A
+  // Filtering when data is greater than baseline
+  // regs 0x2b-0x2e
+  uint8_t sectA[] = { 0x01, 0x01, 0x00, 0x00 };
+  if ((rv = writeBytes(0x2b, sectA, 4)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
+      return false;
+    }
+
+  // Section B
+  // Filtering when data is less than baseline
+  // regs 0x2f-0x32
+  uint8_t sectB[] = { 0x01, 0x01, 0xff, 0x02 };
+  if ((rv = writeBytes(0x2f, sectB, 4)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
+      return false;
+    }
+
+  // Section C
+  // Touch Threshold/Release registers, ELE0-ELE11
+  // regs 0x41-0x58
+  //                __T_  __R_
+  uint8_t sectC[] = { 0x0f, 0x0a, 
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a,
+                      0x0f, 0x0a };
+  if ((rv = writeBytes(0x41, sectC, 24)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
+      return false;
+    }
+
+  // Section D
+  // Filter configuration
+  // reg 0x5d
+  uint8_t filterConf = 0x04;
+  if ((rv = writeBytes(0x5d, &filterConf, 1)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
+      return false;
+    }
+
+  // Section F
+  // Autoconfiguration registers
+  // regs 0x7b-0x7f
+  uint8_t sectF0 = 0x0b;
+  if ((rv = writeBytes(0x7b, &sectF0, 1)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
+      return false;
+    }
+  uint8_t sectF1[] = { 0x9c, 0x65, 0x8c };
+  if ((rv = writeBytes(0x7d, sectF1, 3)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
+      return false;
+    }
+
+  // Section E - this one must be set last, and switches to run mode
+  // Enable all 12 electrodes, and set a pre-calibration to avoid
+  // excessive calibration delay on startup.
+  // reg 0x5e
+  eleConf = 0x8c;
+  if ((rv = writeBytes(0x5e, &eleConf, 1)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
+      return false;
+    }
+
+  return true;
+}
+
+void MPR121::readButtons()
+{
+  uint8_t rv;
+  uint8_t buffer[2];
+
+  // read in the 2 bytes at register 0x00-0x01, and setup the member
+  // variables accordingly.
+
+  readBytes(0x00, buffer, 2);
+
+  m_buttonStates = (buffer[0] | ((buffer[1] & 0x1f) << 8));
+  if (buffer[1] & 0x80)
+    m_overCurrentFault = true;
+  else
+    m_overCurrentFault = false;
+
+  return;
+}

src/mpr121/mpr121.h

@@ -0,0 +1,108 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#pragma once
+
+#include <string>
+#include <mraa/i2c.h>
+
+#define MPR121_I2C_BUS     0
+#define MPR121_DEFAULT_I2C_ADDR    0x5a
+
+namespace upm {
+
+  /**
+   * @brief C++ API for the MPR121 I2C touch sensor
+   *
+   * UPM module for the MPR121 touch sensor
+   *
+   * @ingroup i2c mpr121
+   * @snippet mpr121.cxx Interesting
+   */
+  class MPR121 {
+  public:
+    /**
+     * mpr121 touch sensor constructor
+     *
+     * @param bus i2c bus to use
+     */
+    MPR121(int bus, uint8_t address = MPR121_DEFAULT_I2C_ADDR);
+
+    /**
+     * MPR121 Destructor
+     */
+    ~MPR121();
+
+    /**
+     * Setup a default configuration, based on Application Note 3944
+     * (AN3944):
+     * http://cache.freescale.com/files/sensors/doc/app_note/AN3944.pdf
+     *
+     * After configuration, the sensor will be left in the Run State.
+     *
+     * @return True if configuration succeeded
+     */
+    bool configAN3944();
+
+    /**
+     * Read the button states into the m_buttonStates member variable.  Also
+     * set the m_overCurrentFault variable if an over current is detected.
+     */
+    void readButtons();
+
+    /**
+     * Write value(s) into registers
+     *
+     * @param reg register location to start writing into
+     * @param buffer buffer for data storage
+     * @param len number of bytes to write
+     * @return mraa_result_t
+     */
+    mraa_result_t writeBytes(uint8_t reg, uint8_t *buffer, unsigned int len);
+
+    /**
+     * Read value(s) from registers
+     *
+     * @param reg register location to start reading from
+     * @param buffer buffer for data storage
+     * @param len number of bytes to read
+     */
+    void readBytes(uint8_t reg, uint8_t *buffer, unsigned int len);
+
+    /**
+     * button states
+     */
+    uint16_t m_buttonStates;
+
+    /**
+     * Over current fault detected
+     */
+    bool m_overCurrentFault;
+
+  private:
+    mraa_i2c_context m_i2c;
+    uint8_t m_addr;
+  };
+}
+
+

src/mpr121/pyupm_mpr121.i

@@ -0,0 +1,13 @@
+%module pyupm_mpr121
+%include "../upm.i"
+
+%feature("autodoc", "3");
+
+#ifdef DOXYGEN
+%include "mpr121_doc.i"
+#endif
+
+%include "mpr121.h"
+%{
+    #include "mpr121.h"
+%}