Diff: main.cpp

Revision:

0:8a8f44689157

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Sep 17 19:31:13 2015 +0000
@@ -0,0 +1,207 @@
+/**
+ * A simple single-file program to test the BNO055 breakout board from Adafruit.
+ * There are two BNO055 libraries on MBED, as well as Arduino source code on the Adafruit website,
+ * but none of it worked for me, so I wrote this simple example.
+ *
+ * Some notes:
+ * 1.) You will probably need to reset your microcontroller a few times. The BNO055 is correctly initialized when
+ *      the ID is read correctly and the temperature is not zero (i.e. initBNO055() should return true).
+ * 2.) The BNO055 breakout board uses an external crystal. If you are not using an external crystal, delete the
+ *      I2C write message that sets the chip to using external crystal.
+ */
+
+#include "mbed.h"
+
+Serial pc(USBTX,USBRX);
+I2C i2c(D7, D6);
+
+const int bno055_addr = 0x28 << 1;
+
+const int BNO055_ID_ADDR                                          = 0x00;
+const int BNO055_EULER_H_LSB_ADDR                                 = 0x1A;
+const int BNO055_TEMP_ADDR                                        = 0x34;
+const int BNO055_OPR_MODE_ADDR                                    = 0x3D;
+const int BNO055_CALIB_STAT_ADDR                                  = 0x35;
+const int BNO055_SYS_STAT_ADDR                                    = 0x39;
+const int BNO055_SYS_ERR_ADDR                                     = 0x3A;
+const int BNO055_AXIS_MAP_CONFIG_ADDR                             = 0x41;
+const int BNO055_SYS_TRIGGER_ADDR                                 = 0x3F;
+
+typedef struct CalibStatus_t
+{
+    int mag;
+    int acc;
+    int gyr;
+    int sys;
+} CalibStatus;
+
+typedef struct Euler_t
+{
+    float heading;
+    float pitch;
+    float roll;
+} Euler;
+
+
+/**
+ * Function to write to a single 8-bit register
+ */
+void writeReg(int regAddr, char value)
+{
+    char wbuf[2];
+    wbuf[0] = regAddr;
+    wbuf[1] = value;
+    i2c.write(bno055_addr, wbuf, 2, false);  
+}
+
+/**
+ * Function to read from a single 8-bit register
+ */
+char readReg(int regAddr)
+{
+    char rwbuf = regAddr;
+    i2c.write(bno055_addr, &rwbuf, 1, false);
+    i2c.read(bno055_addr, &rwbuf, 1, false);
+    return rwbuf;
+}
+
+/**
+ * Returns the calibration status of each component
+ */
+CalibStatus readCalibrationStatus()
+{
+    CalibStatus status;
+    int regVal = readReg(BNO055_CALIB_STAT_ADDR);
+        
+    status.mag = regVal & 0x03;
+    status.acc = (regVal >> 2) & 0x03;
+    status.gyr = (regVal >> 4) & 0x03;
+    status.sys = (regVal >> 6) & 0x03;
+    
+    return status;
+}
+
+
+/**
+ * Checks that there are no errors on the accelerometer
+ */
+bool bno055Healthy()
+{
+    int sys_error = readReg(BNO055_SYS_ERR_ADDR);
+    wait(0.001);
+    int sys_stat = readReg(BNO055_SYS_STAT_ADDR);
+    wait(0.001);
+    
+    if(sys_error == 0 && sys_stat == 5)
+        return true;
+    else
+        return false;
+}
+    
+
+/**
+ * Configure and initialize the BNO055
+ */
+bool initBNO055()
+{
+    unsigned char regVal;
+    i2c.frequency(400000);
+    bool startupPass = true;
+    
+    // Do some basic power-up tests
+    regVal = readReg(BNO055_ID_ADDR);
+    if(regVal == 0xA0)
+        pc.printf("BNO055 successfully detected!\r\n");
+    else {
+        pc.printf("ERROR: no BNO055 detected\r\n");
+        startupPass = false;
+    }
+        
+    regVal = readReg(BNO055_TEMP_ADDR);
+    pc.printf("Chip temperature is: %d C\r\n", regVal);
+    
+    if(regVal == 0)
+        startupPass = false;
+ 
+    // Change mode to CONFIG
+    writeReg(BNO055_OPR_MODE_ADDR, 0x00);
+    wait(0.2);
+    
+    regVal = readReg(BNO055_OPR_MODE_ADDR);
+    pc.printf("Change to mode: %d\r\n", regVal);
+    wait(0.1);
+    
+    // Remap axes
+    writeReg(BNO055_AXIS_MAP_CONFIG_ADDR, 0x06);    // b00_00_01_10
+    wait(0.1);    
+
+    // Set to external crystal
+    writeReg(BNO055_SYS_TRIGGER_ADDR, 0x80);
+    wait(0.2);    
+
+    // Change mode to NDOF
+    writeReg(BNO055_OPR_MODE_ADDR, 0x0C);
+    wait(0.2);
+ 
+    regVal = readReg(BNO055_OPR_MODE_ADDR);
+    pc.printf("Change to mode: %d\r\n", regVal);
+    wait(0.1);
+    
+    return startupPass;
+}
+
+/**
+ * Reads the Euler angles, zeroed out
+ */
+Euler getEulerAngles()
+{
+    char buf[16];
+    Euler e;
+    
+    // Read in the Euler angles
+    buf[0] = BNO055_EULER_H_LSB_ADDR;
+    i2c.write(bno055_addr, buf, 1, false);
+    i2c.read(bno055_addr, buf, 6, false);
+    
+    short int euler_head = buf[0] + (buf[1] << 8);
+    short int euler_roll = buf[2] + (buf[3] << 8);
+    short int euler_pitch = buf[4] + (buf[5] << 8);
+    
+    e.heading = ((float)euler_head) / 16.0;
+    e.roll = ((float)euler_roll) / 16.0;
+    e.pitch = ((float)euler_pitch) / 16.0;
+    
+    return e;
+}
+
+int main() {
+
+    bool startupPassed;
+    Euler e;
+
+    // Initialize
+    pc.baud(115200);
+    wait(0.5);
+    startupPassed = initBNO055();   // Note: set LED to RED if this fails
+ 
+    // Read orientation values
+    while(true)
+    {
+        // Make sure that there are no errors
+        if(!bno055Healthy())
+            pc.printf("ERROR: BNO055 has an error/status problem!!!\r\n");
+        
+        // Read in the Euler angles
+        e = getEulerAngles();
+ 
+        wait(0.001);
+ 
+        // Read in the calibration status
+        CalibStatus calStat = readCalibrationStatus();
+        
+        printf("Heading: %7.2f \tRoll: %7.2f \tPitch: %7.2f \tMAG: %d ACC: %d GYR: %d SYS: %d\r\n", e.heading, e.roll, e.pitch,
+            calStat.mag, calStat.acc, calStat.gyr, calStat.sys);
+        
+        wait(0.05);
+    }
+}