Diff: Sensors.cpp

Revision:

0:014ee3239c80

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Sensors.cpp	Thu Nov 08 18:57:18 2012 +0000
@@ -0,0 +1,175 @@
+/* This file is part of the Razor AHRS Firmware */
+#include "AHRS.h"
+
+// I2C code to read the sensors
+
+// Sensor I2C addresses
+#define ACCEL_READ  0xA7
+#define ACCEL_WRITE 0xA6
+#define MAGN_WRITE  0x3C
+#define MAGN_READ   0x3D
+#define GYRO_WRITE  0xD0
+#define GYRO_READ   0xD1
+
+void IMU::I2C_Init()
+{
+    Wire.frequency(100000);
+}
+
+void IMU::Accel_Init()
+{
+    char tx[2];
+
+    tx[0] = 0x2D; // Power register
+    tx[1] = 0x08; // Power register
+    Wire.write(ACCEL_WRITE, tx, 2);
+    wait_ms(5);
+
+    tx[0] = 0x31; // Data format register
+    tx[1] = 0x08; // Set to full resolution
+    Wire.write(ACCEL_WRITE, tx, 2);
+    wait_ms(5);
+
+    // Because our main loop runs at 50Hz we adjust the output data rate to 50Hz (25Hz bandwidth)
+    tx[0] = 0x2C;  // Rate
+    tx[1] = 0x09;  // Set to 50Hz, normal operation
+    Wire.write(ACCEL_WRITE, tx, 2);
+    wait_ms(5);
+}
+
+// Reads x, y and z accelerometer registers
+void IMU::Read_Accel()
+{
+    char buff[6];
+    char tx = 0x32;  // Send address to read from
+
+    Wire.write(ACCEL_WRITE, &tx, 1);
+
+    if (Wire.read(ACCEL_READ, buff, 6) == 0) { // All bytes received?
+        // No multiply by -1 for coordinate system transformation here, because of double negation:
+        // We want the gravity vector, which is negated acceleration vector.
+        accel[0] = (int)buff[3] << 8 | (int)buff[2]; // X axis (internal sensor y axis)
+        accel[1] = (int)buff[1] << 8 | (int)buff[0]; // Y axis (internal sensor x axis)
+        accel[2] = (int)buff[5] << 8 | (int)buff[4]; // Z axis (internal sensor z axis)
+    } else {
+        num_accel_errors++;
+        if (output_errors) pc.printf("!ERR: reading accelerometer" NEW_LINE);
+    }
+}
+
+void IMU::Magn_Init()
+{
+    char tx[2];
+    tx[0] = 0x02; // Mode
+    tx[1] = 0x00; // Set continuous mode (default 10Hz)
+    Wire.write(MAGN_WRITE, tx, 2);
+    wait_ms(5);
+
+    tx[0] = 0x00; // CONFIG_A
+    tx[1] = 0x18; // Set 75Hz
+    Wire.write(MAGN_WRITE, tx, 2);
+    wait_ms(5);
+}
+
+void IMU::Read_Magn()
+{
+    char buff[6];
+    char tx = 0x03;  // Send address to read from
+
+    Wire.write(MAGN_WRITE, &tx, 1);
+
+    if (Wire.read(MAGN_READ, buff, 6) == 0) { // All bytes received?
+// 9DOF Razor IMU SEN-10125 using HMC5843 magnetometer
+#if HW__VERSION_CODE == 10125
+        // MSB byte first, then LSB; X, Y, Z
+        magnetom[0] = -1 * (((int) buff[2]) << 8) | buff[3];  // X axis (internal sensor -y axis)
+        magnetom[1] = -1 * (((int) buff[0]) << 8) | buff[1];  // Y axis (internal sensor -x axis)
+        magnetom[2] = -1 * (((int) buff[4]) << 8) | buff[5];  // Z axis (internal sensor -z axis)
+// 9DOF Razor IMU SEN-10736 using HMC5883L magnetometer
+#elif HW__VERSION_CODE == 10736
+        // MSB byte first, then LSB; Y and Z reversed: X, Z, Y
+        magnetom[0] = -1 * (((int) buff[4]) << 8) | buff[5];  // X axis (internal sensor -y axis)
+        magnetom[1] = -1 * (((int) buff[0]) << 8) | buff[1];  // Y axis (internal sensor -x axis)
+        magnetom[2] = -1 * (((int) buff[2]) << 8) | buff[3];  // Z axis (internal sensor -z axis)
+// 9DOF Sensor Stick SEN-10183 and SEN-10321 using HMC5843 magnetometer
+#elif (HW__VERSION_CODE == 10183) || (HW__VERSION_CODE == 10321)
+        // MSB byte first, then LSB; X, Y, Z
+        magnetom[0] = (((int) buff[0]) << 8) | buff[1];       // X axis (internal sensor x axis)
+        magnetom[1] = -1 * (((int) buff[2]) << 8) | buff[3];  // Y axis (internal sensor -y axis)
+        magnetom[2] = -1 * (((int) buff[4]) << 8) | buff[5];  // Z axis (internal sensor -z axis)
+// 9DOF Sensor Stick SEN-10724 using HMC5883L magnetometer
+#elif HW__VERSION_CODE == 10724
+        // MSB byte first, then LSB; Y and Z reversed: X, Z, Y
+        magnetom[0] =  1 * ((int)buff[0] << 8 | (int)buff[1]); // X axis (internal sensor x axis)
+        magnetom[1] = -1 * ((int)buff[4] << 8 | (int)buff[5]); // Y axis (internal sensor -y axis)
+        magnetom[2] = -1 * ((int)buff[2] << 8 | (int)buff[3]); // Z axis (internal sensor -z axis)
+#endif
+    } else {
+        num_magn_errors++;
+        if (output_errors) pc.printf("!ERR: reading magnetometer" NEW_LINE);
+    }
+}
+
+void IMU::Gyro_Init()
+{
+    char tx[2];
+
+    // Power up reset defaults
+    tx[0] = 0x3E; // Power management
+    tx[1] = 0x80; // ?
+    Wire.write(GYRO_WRITE, tx, 2);
+    wait_ms(5);
+
+    // Select full-scale range of the gyro sensors
+    // Set LP filter bandwidth to 42Hz
+    tx[0] = 0x16; //
+    tx[1] = 0x1B; // DLPF_CFG = 3, FS_SEL = 3
+    Wire.write(GYRO_WRITE, tx, 2);
+    wait_ms(5);
+
+    // Set sample rato to 50Hz
+    tx[0] = 0x15; //
+    tx[1] = 0x0A; //  SMPLRT_DIV = 10 (50Hz)
+    Wire.write(GYRO_WRITE, tx, 2);
+    wait_ms(5);
+
+    // Set clock to PLL with z gyro reference
+    tx[0] = 0x3E;
+    tx[1] = 0x00;
+    Wire.write(GYRO_WRITE, tx, 2);
+    wait_ms(5);
+    
+    // Set offset values
+    foffset[0] = 99.5; // x (standard axis)
+    foffset[1] = -45.0; // y
+    foffset[2] = -29.7; // z
+    // set slope values
+    slope[0] = -1.05;
+    slope[1] = 0.95;
+    slope[2] = 0.47;
+}
+
+// Reads x, y and z gyroscope registers - and temperature
+void IMU::Read_Gyro()
+{
+    char buff[8];
+    int16_t readings[3];
+    char tx = 0x1B; // Sends address to read from
+
+    Wire.write(GYRO_WRITE, &tx, 1);
+
+    if (Wire.read(GYRO_READ, buff, 8) == 0) { // All bytes received?
+        int16_t temp = int16_t(((unsigned char)buff[0] << 8) | (unsigned char)buff[1]);
+        temperature = 35.0 + ((temp + 13200)/280.0); // temperature
+        for(int i = 0; i < 3; i++) {
+            readings[i] = (buff[(i*2)+2] << 8) | (buff[(i*2)+3]);
+            readings[i] -= slope[i] * temperature + foffset[i];
+        }
+        gyro[0] = -1 * readings[1];   // X axis (internal sensor -y axis)
+        gyro[1] = -1 * readings[0];   // Y axis (internal sensor -x axis)
+        gyro[2] = -1 * readings[2];   // Z axis (internal sensor -z axis)
+    } else {
+        num_gyro_errors++;
+        if (output_errors) pc.printf("!ERR: reading gyroscope" NEW_LINE);
+    }
+}