mpu9150: rewrite from scratch

This driver has been rewritten from scratch.  It is implemented as 3
seperate drivers now (but all included as part of the mpu9150 UPM
library):

AK8975 (Magnetometer)
MPU60X0 (Accelerometer, Gyroscope, and Temperature sensor)
MPU9150 (composed of AK8975 and MPU60X0)

Each driver can be used independently and includes examples in
C++/JS/Python.

Commonly used capabilities are supported, and methods/register
definitions exist to easily implement any desired functionality that
is missing.  Interrupt support has also been added.

Scaling support has also been properly implemented for both the
Accelerometer and Gyroscope.

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

src/mpu9150/mpu60x0.cxx

@@ -0,0 +1,405 @@
+/*
+ * 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 <unistd.h>
+#include <iostream>
+#include <string.h>
+
+#include "mpu60x0.h"
+
+using namespace upm;
+using namespace std;
+
+
+MPU60X0::MPU60X0(int bus, uint8_t address) :
+  m_i2c(bus), m_gpioIRQ(0)
+{
+  m_addr = address;
+
+  m_accelX = 0.0;
+  m_accelY = 0.0;
+  m_accelZ = 0.0;
+  
+  m_gyroX = 0.0;
+  m_gyroY = 0.0;
+  m_gyroZ = 0.0;
+  
+  m_temp = 0.0;
+
+  m_accelScale = 1.0;
+  m_gyroScale = 1.0;
+
+  mraa_result_t rv;
+  if ( (rv = m_i2c.address(m_addr)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": Could not initialize i2c address. " << endl;
+      mraa_result_print(rv);
+      return;
+    }
+}
+
+MPU60X0::~MPU60X0()
+{
+  uninstallISR();
+}
+
+bool MPU60X0::init()
+{
+  // first, take the device out of sleep mode
+  if (!setSleep(false))
+    {
+      cerr << __FUNCTION__ << ": Unable to wake up device" << endl;
+      return false;
+    }
+
+  // set the clock source to use the gyroscope PLL rather than the
+  // internal clock for stability
+  if (!setClockSource(PLL_XG))
+    {
+      cerr << __FUNCTION__ << ": Unable to set clock source" << endl;
+      return false;
+    }
+
+  usleep(5000);
+
+  // enable temperature measurement (default on power up, but let's be sure)
+  enableTemperatureSensor(true);
+
+  // set the gyro and accel scale bits to reasonable values
+  setGyroscopeScale(FS_500);
+  setAccelerometerScale(AFS_2);
+
+  // enable the DLPF
+  setDigitalLowPassFilter(DLPF_94_98);
+
+  // let things stabilize...
+  usleep(100000);
+
+  return true;
+}
+
+
+void MPU60X0::update()
+{
+  // read all of the sensor registers - accel, gyro, and temp
+  uint8_t buffer[14];
+
+  memset(buffer, 0, 14);
+  readRegs(REG_ACCEL_XOUT_H, buffer, 14);
+
+  int16_t ax, ay, az;
+  int16_t temp;
+  int16_t gx, gy, gz;
+
+  ax =  ( (buffer[0] << 8) | buffer[1] );
+  ay =  ( (buffer[2] << 8) | buffer[3] );
+  az =  ( (buffer[4] << 8) | buffer[5] );
+
+  temp = ( (buffer[6] << 8) | buffer[7] );
+
+  gx =  ( (buffer[8] << 8) | buffer[9] );
+  gy =  ( (buffer[10] << 8) | buffer[11] );
+  gz =  ( (buffer[12] << 8) | buffer[13] );
+
+  // now stash them
+  m_accelX = float(ax);
+  m_accelY = float(ay);
+  m_accelZ = float(az);
+
+  m_temp = float(temp);
+
+  m_gyroX = float(gx);
+  m_gyroY = float(gy);
+  m_gyroZ = float(gz);
+}
+
+uint8_t MPU60X0::readReg(uint8_t reg)
+{
+  return m_i2c.readReg(reg);
+}
+
+void MPU60X0::readRegs(uint8_t reg, uint8_t *buf, int len)
+{
+  m_i2c.readBytesReg(reg, buf, len);
+}
+
+bool MPU60X0::writeReg(uint8_t reg, uint8_t val)
+{
+  mraa_result_t rv;
+  if ((rv = m_i2c.writeReg(reg, val)) != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": failed:" << endl;
+      mraa_result_print(rv);
+      return false;
+    } 
+  
+  return true;
+}
+
+bool MPU60X0::setSleep(bool enable)
+{
+  uint8_t reg = readReg(REG_PWR_MGMT_1);
+
+  if (enable)
+    reg |= PWR_SLEEP;
+  else
+    reg &= ~PWR_SLEEP;
+
+  return writeReg(REG_PWR_MGMT_1, reg);
+}
+
+bool MPU60X0::setClockSource(CLKSEL_T clk)
+{
+  uint8_t reg = readReg(REG_PWR_MGMT_1);
+
+  reg &= ~(_CLKSEL_MASK << _CLKSEL_SHIFT);
+
+  reg |= (clk << _CLKSEL_SHIFT);
+
+  return writeReg(REG_PWR_MGMT_1, reg);
+}
+
+bool MPU60X0::setGyroscopeScale(FS_SEL_T scale)
+{
+  uint8_t reg = readReg(REG_GYRO_CONFIG);
+
+  reg &= ~(_FS_SEL_MASK << _FS_SEL_SHIFT);
+
+  reg |= (scale << _FS_SEL_SHIFT);
+
+  if (!writeReg(REG_GYRO_CONFIG, reg))
+    {
+      return false;
+    }
+
+  // store scaling factor
+
+  switch (scale)
+    {
+    case FS_250:
+      m_gyroScale = 131.0;
+      break;
+
+    case FS_500:
+      m_gyroScale = 65.5;
+      break;
+
+    case FS_1000:
+      m_gyroScale = 32.8;
+      break;
+
+    case FS_2000:
+      m_gyroScale = 16.4;
+      break;
+
+    default: // should never occur, but...
+      m_gyroScale = 1.0;        // set a safe, though incorrect value
+      cerr << __FUNCTION__ << ": internal error, unsupported scale" << endl;
+      break;
+    }
+
+  return true;
+}
+
+bool MPU60X0::setAccelerometerScale(AFS_SEL_T scale)
+{
+  uint8_t reg = readReg(REG_ACCEL_CONFIG);
+
+  reg &= ~(_AFS_SEL_MASK << _AFS_SEL_SHIFT);
+
+  reg |= (scale << _AFS_SEL_SHIFT);
+
+  if (!writeReg(REG_ACCEL_CONFIG, reg))
+    {
+      return false;
+    }
+
+  // store scaling factor
+  
+  switch (scale)
+    {
+    case AFS_2:
+      m_accelScale = 16384.0;
+      break;
+
+    case AFS_4:
+      m_accelScale = 8192.0;
+      break;
+
+    case AFS_8:
+      m_accelScale = 4096.0;
+      break;
+
+    case AFS_16:
+      m_accelScale = 2048.0;
+      break;
+
+    default: // should never occur, but...
+      m_accelScale = 1.0;        // set a safe, though incorrect value
+      cerr << __FUNCTION__ << ": internal error, unsupported scale" << endl;
+      break;
+    }
+
+  return true;
+}
+
+bool MPU60X0::setDigitalLowPassFilter(DLPF_CFG_T dlp)
+{
+  uint8_t reg = readReg(REG_CONFIG);
+
+  reg &= ~(_CONFIG_DLPF_MASK << _CONFIG_DLPF_SHIFT);
+
+  reg |= (dlp << _CONFIG_DLPF_SHIFT);
+
+  return writeReg(REG_CONFIG, reg);
+}
+
+bool MPU60X0::setSampleRateDivider(uint8_t div)
+{
+  return writeReg(REG_SMPLRT_DIV, div);
+}
+
+uint8_t MPU60X0::getSampleRateDivider()
+{
+  return readReg(REG_SMPLRT_DIV);
+}
+
+void MPU60X0::getAccelerometer(float *x, float *y, float *z)
+{
+  if (x)
+    *x = m_accelX / m_accelScale;
+
+  if (y)
+    *y = m_accelY / m_accelScale;
+
+  if (z)
+    *z = m_accelZ / m_accelScale;
+}
+
+void MPU60X0::getGyroscope(float *x, float *y, float *z)
+{
+  if (x)
+    *x = m_gyroX / m_gyroScale;
+
+  if (y)
+    *y = m_gyroY / m_gyroScale;
+
+  if (z)
+    *z = m_gyroZ / m_gyroScale;
+}
+
+float MPU60X0::getTemperature()
+{
+  // this equation is taken from the datasheet
+  return (m_temp / 340.0) + 36.53;
+}
+
+bool MPU60X0::enableTemperatureSensor(bool enable)
+{
+  uint8_t reg = readReg(REG_PWR_MGMT_1);
+
+  if (enable)
+    reg &= ~TEMP_DIS;
+  else
+    reg |= TEMP_DIS;
+
+  return writeReg(REG_PWR_MGMT_1, reg);
+}
+
+bool MPU60X0::setExternalSync(EXT_SYNC_SET_T val)
+{
+  uint8_t reg = readReg(REG_CONFIG);
+
+  reg &= ~(_CONFIG_EXT_SYNC_SET_MASK << _CONFIG_EXT_SYNC_SET_SHIFT);
+
+  reg |= (val << _CONFIG_EXT_SYNC_SET_SHIFT);
+
+  return writeReg(REG_CONFIG, reg);
+}
+
+bool MPU60X0::enableI2CBypass(bool enable)
+{
+  uint8_t reg = readReg(REG_INT_PIN_CFG);
+
+  if (enable)
+    reg |= I2C_BYPASS_ENABLE;
+  else
+    reg &= ~I2C_BYPASS_ENABLE;
+
+  return writeReg(REG_INT_PIN_CFG, reg);
+}
+
+bool MPU60X0::setMotionDetectionThreshold(uint8_t thr)
+{
+  return writeReg(REG_MOT_THR, thr);
+}
+
+uint8_t MPU60X0::getInterruptStatus()
+{
+  return readReg(REG_INT_STATUS);
+}
+
+bool MPU60X0::setInterruptEnables(uint8_t enables)
+{
+  return writeReg(REG_INT_ENABLE, enables);
+}
+
+uint8_t MPU60X0::getInterruptEnables()
+{
+  return readReg(REG_INT_ENABLE);
+}
+
+bool MPU60X0::setInterruptPinConfig(uint8_t cfg)
+{
+  return writeReg(REG_INT_PIN_CFG, cfg);
+}
+
+uint8_t MPU60X0::getInterruptPinConfig()
+{
+  return readReg(REG_INT_PIN_CFG);
+}
+
+void MPU60X0::installISR(int gpio, mraa::Edge level, 
+                         void (*isr)(void *), void *arg)
+{
+  // delete any existing ISR and GPIO context
+  uninstallISR();
+
+  // greate gpio context
+  m_gpioIRQ = new mraa::Gpio(gpio);
+
+  m_gpioIRQ->dir(mraa::DIR_IN);
+  m_gpioIRQ->isr(level, isr, arg);
+}
+
+void MPU60X0::uninstallISR()
+{
+  if (m_gpioIRQ)
+    {
+      m_gpioIRQ->isrExit();
+      delete m_gpioIRQ;
+      
+      m_gpioIRQ = 0;
+    }
+}