mma7660: Initial implementation

This was tested on the Grove I2C 3-axis digital accelerometer.

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/mma7660/mma7660.cxx

@@ -0,0 +1,249 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 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 "mma7660.h"
+
+using namespace upm;
+using namespace std;
+
+
+MMA7660::MMA7660(int bus, uint8_t address)
+{
+  m_addr = address;
+  m_isrInstalled = false;
+
+  // setup our i2c link
+  if ( !(m_i2c = mraa_i2c_init(bus)) )
+    {
+      cerr << "MMA7660: mraa_i2c_init() failed." << endl;
+      return;
+    }
+      
+  mraa_result_t rv;
+  
+  if ( (rv = mraa_i2c_address(m_i2c, m_addr)) != MRAA_SUCCESS)
+    {
+      cerr << "MMA7660: Could not initialize i2c bus. " << endl;
+      mraa_result_print(rv);
+      return;
+    }
+}
+
+MMA7660::~MMA7660()
+{
+  if (m_isrInstalled)
+    uninstallISR();
+
+  setModeStandby();
+  mraa_i2c_stop(m_i2c);
+}
+
+bool MMA7660::writeByte(uint8_t reg, uint8_t byte)
+{
+  mraa_result_t rv = mraa_i2c_write_byte_data(m_i2c, byte, reg);
+
+  if (rv != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": mraa_i2c_write_byte() failed." << endl;
+      mraa_result_print(rv);
+      return false;
+    }
+
+  return true;
+}
+
+uint8_t MMA7660::readByte(uint8_t reg)
+{
+  return mraa_i2c_read_byte_data(m_i2c, reg);
+}
+
+void MMA7660::getRawValues(int *x, int *y, int *z)
+{
+  *x = getVerifiedAxis(REG_XOUT);
+  *y = getVerifiedAxis(REG_YOUT);
+  *z = getVerifiedAxis(REG_ZOUT);
+}
+
+void MMA7660::setModeActive()
+{
+  uint8_t modeReg = readByte(REG_MODE);
+
+  // The D2 (TON bit) should be cleared, and the MODE bit set
+
+  modeReg &= ~MODE_TON;
+  modeReg |= MODE_MODE;
+
+  writeByte(REG_MODE, modeReg);
+}
+
+void MMA7660::setModeStandby()
+{
+  uint8_t modeReg = readByte(REG_MODE);
+
+  // the D0 (mode bit) and D2 (TON bit) should be cleared.
+
+  modeReg &= ~MODE_TON;
+  modeReg &= ~MODE_MODE;
+
+  writeByte(REG_MODE, modeReg);
+}
+
+// read an axis value, verifying it's validity
+int MMA7660::getVerifiedAxis(MMA7660_REG_T axis)
+{
+  // We only want one of the 3 axes
+
+  if (axis > 2)
+    {
+      cerr << __FUNCTION__ << ": axis must be 0, 1, or 2." << endl;
+      return 0;
+    }
+
+  // we need to check the alert bit and sign bits if the alert bit is
+  // set, this means that the register was being updated when the
+  // register was read, so re-read until it's clear.
+  
+  uint8_t val;
+  do {
+    val = readByte(axis);
+
+    // check alert bit
+  } while (val & 0x40);
+
+  // shift the sign bit over, and compensate
+  return (char(val << 2) / 4);
+}
+
+// read the tilt register, verifying it's validity
+uint8_t MMA7660::getVerifiedTilt()
+{
+  // we need to check the alert bit and sign bits if the alert bit is
+  // set, this means that the register was being updated when the
+  // register was read, so re-read until it's clear.
+  
+  uint8_t val;
+  do {
+    val = readByte(REG_TILT);
+
+    // check alert bit
+  } while (val & 0x40);
+
+  // shift the sign bit over, and compensate
+  return val;
+}
+
+uint8_t MMA7660::tiltBackFront()
+{
+  uint8_t val = getVerifiedTilt();
+
+  // mask off the bits we don't care about
+  val &= 0x03;
+  return val;
+}
+
+uint8_t MMA7660::tiltLandscapePortrait()
+{
+  uint8_t val = getVerifiedTilt();
+
+  // mask off the bits we don't care about
+  val >>= 2;
+  val &= 0x07;
+  return val;
+}
+
+bool MMA7660::tiltTap()
+{
+  uint8_t val = getVerifiedTilt();
+
+  if (val & 0x20)
+    return true;
+  else
+    return false;
+}
+
+bool MMA7660::tiltShake()
+{
+  uint8_t val = getVerifiedTilt();
+
+  if (val & 0x80)
+    return true;
+  else
+    return false;
+}
+
+void MMA7660::installISR(int pin, void (*isr)(void *), void *arg)
+{
+  if (m_isrInstalled)
+    uninstallISR();
+
+  if ( !(m_gpio = mraa_gpio_init(pin)) )
+    {
+      cerr << __FUNCTION__ << ": mraa_gpio_init() failed" << endl;
+      return;
+    }
+
+  mraa_gpio_dir(m_gpio, MRAA_GPIO_IN);
+
+  // install our interrupt handler
+  mraa_gpio_isr(m_gpio, MRAA_GPIO_EDGE_RISING, 
+                isr, arg);
+  m_isrInstalled = true;
+}
+
+void MMA7660::uninstallISR()
+{
+  if (!m_isrInstalled)
+    return;
+
+  mraa_gpio_isr_exit(m_gpio);
+  m_isrInstalled = false;
+  mraa_gpio_close(m_gpio);
+}
+
+bool MMA7660::setInterruptBits(uint8_t ibits)
+{
+  return writeByte(REG_INTSU, ibits);
+}
+
+bool MMA7660::setSampleRate(MMA7660_AUTOSLEEP_T sr)
+{
+  return writeByte(REG_SR, sr);
+}
+
+void MMA7660::getAcceleration(float *ax, float *ay, float *az)
+{
+  int x, y, z;
+
+  getRawValues(&x, &y, &z);
+
+  // 21.33, typical counts/g
+
+  *ax = x/21.33;
+  *ay = y/21.33;
+  *az = z/21.33;
+}
+