Diff: MMA7455.cpp

Revision:

4:b32cf4ef45c5

Child:

12:15597e45eea0

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MMA7455.cpp	Fri Oct 18 12:48:58 2013 +0200
@@ -0,0 +1,298 @@
+
+/******************************************************************************
+ * Includes
+ *****************************************************************************/
+
+#include "mbed.h"
+#include "mbed_debug.h"
+
+#include "MMA7455.h"
+
+/******************************************************************************
+ * Defines and typedefs
+ *****************************************************************************/
+
+#define MMA7455_I2C_ADDR (0x1D << 1)
+
+#define MMA7455_ADDR_XOUTL  0x00
+#define MMA7455_ADDR_XOUTH  0x01
+#define MMA7455_ADDR_YOUTL  0x02
+#define MMA7455_ADDR_YOUTH  0x03
+#define MMA7455_ADDR_ZOUTL  0x04
+#define MMA7455_ADDR_ZOUTH  0x05
+#define MMA7455_ADDR_XOUT8  0x06
+#define MMA7455_ADDR_YOUT8  0x07
+#define MMA7455_ADDR_ZOUT8  0x08
+#define MMA7455_ADDR_STATUS 0x09
+#define MMA7455_ADDR_DETSRC 0x0A
+#define MMA7455_ADDR_TOUT   0x0B
+#define MMA7455_ADDR_I2CAD  0x0D
+#define MMA7455_ADDR_USRINF 0x0E
+#define MMA7455_ADDR_WHOAMI 0x0F
+#define MMA7455_ADDR_XOFFL  0x10
+#define MMA7455_ADDR_XOFFH  0x11
+#define MMA7455_ADDR_YOFFL  0x12
+#define MMA7455_ADDR_YOFFH  0x13
+#define MMA7455_ADDR_ZOFFL  0x14
+#define MMA7455_ADDR_ZOFFH  0x15
+#define MMA7455_ADDR_MCTL   0x16
+#define MMA7455_ADDR_INTRST 0x17
+#define MMA7455_ADDR_CTL1   0x18
+#define MMA7455_ADDR_CTL2   0x19
+#define MMA7455_ADDR_LDTH   0x1A
+#define MMA7455_ADDR_PDTH   0x1B
+#define MMA7455_ADDR_PW     0x1C
+#define MMA7455_ADDR_LT     0x1D
+#define MMA7455_ADDR_TW     0x1E
+
+#define MMA7455_MCTL_MODE(m) ((m) << 0)
+#define MMA7455_MCTL_GLVL(g) ((g) << 2)
+
+#define MMA7455_STATUS_DRDY (1 << 0)
+#define MMA7455_STATUS_DOVR (1 << 1)
+#define MMA7455_STATUS_PERR (1 << 2)
+
+
+MMA7455::MMA7455(PinName sda, PinName scl) : _i2c(sda, scl)
+{
+    _mode = ModeStandby;
+    _range = Range_8g;
+
+    _xOff = 0;
+    _yOff = 0;
+    _zOff = 0;
+}
+
+bool MMA7455::setMode(Mode mode) {
+    bool result = false;
+    int mCtrl = 0;
+
+    do {
+        mCtrl = getModeControl();
+        if (mCtrl < 0) break;
+
+        mCtrl &= ~(0x03 << 0);
+        mCtrl |= MMA7455_MCTL_MODE(mode);
+
+        if (setModeControl((uint8_t)mCtrl) < 0) {
+            break;
+        }
+
+        _mode = mode;
+        result = true;
+    } while(0);
+
+
+
+    return result;
+}
+
+bool MMA7455::setRange(Range range) {
+    bool result = false;
+    int mCtrl = 0;
+
+    do {
+        mCtrl = getModeControl();
+        if (mCtrl < 0) break;
+
+        mCtrl &= ~(0x03 << 2);
+        mCtrl |= MMA7455_MCTL_GLVL(range);
+
+        if (setModeControl((uint8_t)mCtrl) < 0) {
+            break;
+        }
+
+        _range = range;
+        result = true;
+    } while(0);
+
+
+
+    return result;
+
+}
+
+bool MMA7455::read(int32_t& x, int32_t& y, int32_t& z) {
+    bool result = false;
+
+
+    // nothing to read in standby mode
+    if (_mode == ModeStandby) return false;
+
+    // wait for ready flag
+    int status = 0;
+    do {
+      status = getStatus();
+    } while (status >= 0 && (status & MMA7455_STATUS_DRDY) == 0);
+
+
+    do {
+        if (status < 0) break;
+
+
+        char buf[6];
+        buf[0] = MMA7455_ADDR_XOUTL;
+        if (_i2c.write(MMA7455_I2C_ADDR, buf, 1) != 0) break;
+        if (_i2c.read(MMA7455_I2C_ADDR, buf, 6) != 0) break;
+
+        // check if second bit is set in high byte -> negative value
+        // expand negative value to full byte
+        if (buf[1] & 0x02) buf[1] |= 0xFC;
+        if (buf[3] & 0x02) buf[3] |= 0xFC;
+        if (buf[5] & 0x02) buf[5] |= 0xFC;
+
+        x = (int16_t)((buf[1] << 8) | buf[0]) + _xOff;
+        y = (int16_t)((buf[3] << 8) | buf[2]) + _yOff;
+        z = (int16_t)((buf[5] << 8) | buf[4]) + _zOff;
+
+
+        result = true;
+
+    } while(0);
+
+
+    return result;
+}
+
+bool MMA7455::calibrate() {
+    bool result = false;
+    bool failed = false;
+
+    int32_t x = 0;
+    int32_t y = 0;
+    int32_t z = 0;
+
+    int32_t xr = 0;
+    int32_t yr = 0;
+    int32_t zr = 0;
+
+    int xOff = 0;
+    int yOff = 0;
+    int zOff = 16;
+    if (_range == Range_2g) {
+        zOff = 64;
+    }
+    if (_range == Range_4g) {
+        zOff = 32;
+    }
+
+    do {
+
+        // get an average of 6 values
+        for (int i = 0; i < 6; i++) {
+            if (!read(xr, yr, zr)) {
+                failed = true;
+                break;
+            }
+            x += xr;
+            y += yr;
+            z += zr;
+
+            wait_ms(100);
+        }
+
+        if (failed) break;
+        x /= 6;
+        y /= 6;
+        z /= 6;
+
+        xOff -= x;
+        yOff -= y;
+        zOff -= z;
+
+        /*
+         * For some reason we have not got correct/reliable calibration
+         * by using the offset drift registers. Instead we are
+         * calculating the offsets and store them in member variables.
+         *
+         * These member variables are then used in the read() method
+         */
+
+        _xOff = xOff;
+        _yOff = yOff;
+        _zOff = zOff;
+
+
+        result = true;
+
+    } while (0);
+
+
+
+    return result;
+}
+
+bool MMA7455::setCalibrationOffsets(int32_t xOff, int32_t yOff, int32_t zOff) {
+    _xOff = xOff;
+    _yOff = yOff;
+    _zOff = zOff;
+
+    return true;
+}
+
+bool MMA7455::getCalibrationOffsets(int32_t& xOff, int32_t& yOff, int32_t& zOff) {
+    xOff = _xOff;
+    yOff = _yOff;
+    zOff = _zOff;
+
+    return true;
+}
+
+int MMA7455::getStatus() {
+    int result = -1;
+    char data[1];
+
+    do {
+        data[0] = MMA7455_ADDR_STATUS;
+        if (_i2c.write(MMA7455_I2C_ADDR, data, 1) != 0) break;
+
+        if (_i2c.read(MMA7455_I2C_ADDR, data, 1) != 0) break;
+
+        result = data[0];
+
+    } while (0);
+
+
+
+    return result;
+}
+
+int MMA7455::getModeControl() {
+
+    int result = -1;
+    char data[1];
+
+    do {
+        data[0] = MMA7455_ADDR_MCTL;
+        if (_i2c.write(MMA7455_I2C_ADDR, data, 1) != 0) break;
+
+        if (_i2c.read(MMA7455_I2C_ADDR, data, 1) != 0) break;
+
+        result = data[0];
+
+    } while (0);
+
+
+
+    return result;
+}
+
+int MMA7455::setModeControl(uint8_t mctl) {
+    int result = -1;
+    char data[2];
+
+    do {
+        data[0] = MMA7455_ADDR_MCTL;
+        data[1] = (char)mctl;
+        if (_i2c.write(MMA7455_I2C_ADDR, data, 2) != 0) break;
+
+        result = 0;
+
+    } while (0);
+
+
+
+    return result;
+}
+
+