Revision 0:2edbd561b520, committed 2014-03-08

Comitter:

brunoalfano

Date:

Sat Mar 08 12:38:14 2014 +0000

Commit message:

First version of a simple MPU6000 SPI library to read sensors' data

Changed in this revision

diff -r 000000000000 -r 2edbd561b520 MPU6000.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MPU6000.cpp	Sat Mar 08 12:38:14 2014 +0000
@@ -0,0 +1,348 @@
+/*CODED by Bruno Alfano on 07/03/2014
+www.xene.it
+*/
+
+#include <mbed.h>
+#include "MPU6000.h"
+
+mpu6000_spi::mpu6000_spi(SPI& _spi, PinName _cs) : spi(_spi), cs(_cs) {}
+
+/*-----------------------------------------------------------------------------------------------
+                                    INITIALIZATION
+usage: call this function at startup, giving the sample rate divider (raging from 0 to 255) and
+low pass filter value; suitable values are:
+BITS_DLPF_CFG_256HZ_NOLPF2
+BITS_DLPF_CFG_188HZ
+BITS_DLPF_CFG_98HZ
+BITS_DLPF_CFG_42HZ
+BITS_DLPF_CFG_20HZ
+BITS_DLPF_CFG_10HZ 
+BITS_DLPF_CFG_5HZ 
+BITS_DLPF_CFG_2100HZ_NOLPF
+returns 1 if an error occurred
+-----------------------------------------------------------------------------------------------*/
+bool mpu6000_spi::init(int sample_rate_div,int low_pass_filter){
+    unsigned int response;
+    spi.format(8,0);
+    spi.frequency(1000000);
+    //FIRST OF ALL DISABLE I2C
+    select();
+    response=spi.write(MPUREG_USER_CTRL);
+    response=spi.write(BIT_I2C_IF_DIS);
+    deselect();
+    //RESET CHIP
+    select();
+    response=spi.write(MPUREG_PWR_MGMT_1);
+    response=spi.write(BIT_H_RESET); 
+    deselect();
+    wait(0.15);
+    //WAKE UP AND SET GYROZ CLOCK
+    select();
+    response=spi.write(MPUREG_PWR_MGMT_1);
+    response=spi.write(MPU_CLK_SEL_PLLGYROZ); 
+    deselect();
+    //DISABLE I2C
+    select();
+    response=spi.write(MPUREG_USER_CTRL);
+    response=spi.write(BIT_I2C_IF_DIS);
+    deselect();
+    //WHO AM I?
+    select();
+    response=spi.write(MPUREG_WHOAMI|READ_FLAG);
+    response=spi.write(0x00);
+    deselect();
+    if(response<100){return 0;}//COULDN'T RECEIVE WHOAMI
+    //SET SAMPLE RATE
+    select();
+    response=spi.write(MPUREG_SMPLRT_DIV);
+    response=spi.write(sample_rate_div); 
+    deselect();
+    // FS & DLPF
+    select();
+    response=spi.write(MPUREG_CONFIG);
+    response=spi.write(low_pass_filter);
+    deselect();
+    //DISABLE INTERRUPTS
+    select();
+    response=spi.write(MPUREG_INT_ENABLE);
+    response=spi.write(0x00);
+    deselect();
+    return 0;
+}
+
+/*-----------------------------------------------------------------------------------------------
+                                ACCELEROMETER SCALE
+usage: call this function at startup, after initialization, to set the right range for the
+accelerometers. Suitable ranges are:
+BITS_FS_2G
+BITS_FS_4G
+BITS_FS_8G
+BITS_FS_16G
+returns the range set (2,4,8 or 16)
+-----------------------------------------------------------------------------------------------*/
+unsigned int mpu6000_spi::set_acc_scale(int scale){
+    unsigned int temp_scale;
+    select();
+    spi.write(MPUREG_ACCEL_CONFIG);
+    spi.write(scale);  
+    deselect();    
+    switch (scale){
+        case BITS_FS_2G:
+            acc_divider=16384;
+        break;
+        case BITS_FS_4G:
+            acc_divider=8192;
+        break;
+        case BITS_FS_8G:
+            acc_divider=4096;
+        break;
+        case BITS_FS_16G:
+            acc_divider=2048;
+        break;   
+    }
+    wait(0.01);
+    select();
+    temp_scale=spi.write(MPUREG_ACCEL_CONFIG|READ_FLAG);
+    temp_scale=spi.write(0x00);  
+    deselect();
+    switch (temp_scale){
+        case BITS_FS_2G:
+            temp_scale=2;
+        break;
+        case BITS_FS_4G:
+            temp_scale=4;
+        break;
+        case BITS_FS_8G:
+            temp_scale=8;
+        break;
+        case BITS_FS_16G:
+            temp_scale=16;
+        break;   
+    }
+    return temp_scale;
+}
+
+
+/*-----------------------------------------------------------------------------------------------
+                                GYROSCOPE SCALE
+usage: call this function at startup, after initialization, to set the right range for the
+gyroscopes. Suitable ranges are:
+BITS_FS_250DPS
+BITS_FS_500DPS
+BITS_FS_1000DPS
+BITS_FS_2000DPS
+returns the range set (250,500,1000 or 2000)
+-----------------------------------------------------------------------------------------------*/
+unsigned int mpu6000_spi::set_gyro_scale(int scale){
+    unsigned int temp_scale;
+    select();
+    spi.write(MPUREG_GYRO_CONFIG);
+    spi.write(scale);  
+    deselect();    
+    switch (scale){
+        case BITS_FS_250DPS:
+            gyro_divider=131;
+        break;
+        case BITS_FS_500DPS:
+            gyro_divider=65.5;
+        break;
+        case BITS_FS_1000DPS:
+            gyro_divider=32.8;
+        break;
+        case BITS_FS_2000DPS:
+            gyro_divider=16.4;
+        break;   
+    }
+    wait(0.01);
+    select();
+    temp_scale=spi.write(MPUREG_GYRO_CONFIG|READ_FLAG);
+    temp_scale=spi.write(0x00);  
+    deselect();
+    switch (temp_scale){
+        case BITS_FS_250DPS:
+            temp_scale=250;
+        break;
+        case BITS_FS_500DPS:
+            temp_scale=500;
+        break;
+        case BITS_FS_1000DPS:
+            temp_scale=1000;
+        break;
+        case BITS_FS_2000DPS:
+            temp_scale=2000;
+        break;   
+    }
+    return temp_scale;
+}
+
+
+/*-----------------------------------------------------------------------------------------------
+                                WHO AM I?
+usage: call this function to know if SPI is working correctly. It checks the I2C address of the
+mpu6000 which should be 104 when in SPI mode.
+returns the I2C address (104)
+-----------------------------------------------------------------------------------------------*/
+unsigned int mpu6000_spi::whoami(){
+    unsigned int response;
+    select();
+    response=spi.write(MPUREG_WHOAMI|READ_FLAG);
+    response=spi.write(0x00);
+    deselect();
+    return response;
+}
+
+
+/*-----------------------------------------------------------------------------------------------
+                                READ ACCELEROMETER
+usage: call this function to read accelerometer data. Axis represents selected axis:
+0 -> X axis
+1 -> Y axis
+2 -> Z axis
+returns the value in Gs
+-----------------------------------------------------------------------------------------------*/
+float mpu6000_spi::read_acc(int axis){
+    uint8_t responseH,responseL;
+    int16_t bit_data;
+    float data;
+    select();
+    switch (axis){
+        case 0:
+        responseH=spi.write(MPUREG_ACCEL_XOUT_H | READ_FLAG);
+        break;
+        case 1:
+        responseH=spi.write(MPUREG_ACCEL_YOUT_H | READ_FLAG);
+        break;
+        case 2:
+        responseH=spi.write(MPUREG_ACCEL_ZOUT_H | READ_FLAG);
+        break;
+    }
+    responseH=spi.write(0x00);
+    responseL=spi.write(0x00);
+    bit_data=((int16_t)responseH<<8)|responseL;
+    data=(float)bit_data;
+    data=data/acc_divider;
+    deselect();
+    return data;
+}
+
+/*-----------------------------------------------------------------------------------------------
+                                READ GYROSCOPE
+usage: call this function to read gyroscope data. Axis represents selected axis:
+0 -> X axis
+1 -> Y axis
+2 -> Z axis
+returns the value in Degrees per second
+-----------------------------------------------------------------------------------------------*/
+float mpu6000_spi::read_rot(int axis){
+    uint8_t responseH,responseL;
+    int16_t bit_data;
+    float data;
+    select();
+    switch (axis){
+        case 0:
+        responseH=spi.write(MPUREG_GYRO_XOUT_H | READ_FLAG);
+        break;
+        case 1:
+        responseH=spi.write(MPUREG_GYRO_YOUT_H | READ_FLAG);
+        break;
+        case 2:
+        responseH=spi.write(MPUREG_GYRO_ZOUT_H | READ_FLAG);
+        break;
+    }
+    responseH=spi.write(0x00);
+    responseL=spi.write(0x00);
+    bit_data=((int16_t)responseH<<8)|responseL;
+    data=(float)bit_data;
+    data=data/gyro_divider;
+    deselect();
+    return data;
+}
+
+/*-----------------------------------------------------------------------------------------------
+                                READ TEMPERATURE
+usage: call this function to read temperature data. 
+returns the value in °C
+-----------------------------------------------------------------------------------------------*/
+float mpu6000_spi::read_temp(){
+    uint8_t responseH,responseL;
+    int16_t bit_data;
+    float data;
+    select();
+    responseH=spi.write(MPUREG_TEMP_OUT_H | READ_FLAG);
+    responseH=spi.write(0x00);
+    responseL=spi.write(0x00);
+    bit_data=((int16_t)responseH<<8)|responseL;
+    data=(float)bit_data;
+    data=(data/340)+36.53;
+    deselect();
+    return data;
+}
+
+/*-----------------------------------------------------------------------------------------------
+                                READ ACCELEROMETER CALIBRATION
+usage: call this function to read accelerometer data. Axis represents selected axis:
+0 -> X axis
+1 -> Y axis
+2 -> Z axis
+returns Factory Trim value
+-----------------------------------------------------------------------------------------------*/
+int mpu6000_spi::calib_acc(int axis){
+    uint8_t responseH,responseL,calib_data;
+    int temp_scale;
+    //READ CURRENT ACC SCALE
+    select();
+    responseH=spi.write(MPUREG_ACCEL_CONFIG|READ_FLAG);
+    temp_scale=spi.write(0x00);  
+    deselect();
+    wait(0.01);
+    set_acc_scale(BITS_FS_8G);
+    wait(0.01);
+    //ENABLE SELF TEST
+    select();
+    responseH=spi.write(MPUREG_ACCEL_CONFIG);
+    temp_scale=spi.write(0x80>>axis);  
+    deselect();
+    wait(0.01);
+    select();
+    responseH=spi.write(MPUREG_SELF_TEST_X|READ_FLAG);
+    switch(axis){
+        case 0:
+            responseH=spi.write(0x00);
+            responseL=spi.write(0x00);
+            responseL=spi.write(0x00);
+            responseL=spi.write(0x00);
+            calib_data=((responseH&11100000)>>3)|((responseL&00110000)>>4);
+        break;
+        case 1:
+            responseH=spi.write(0x00);
+            responseH=spi.write(0x00);
+            responseL=spi.write(0x00);
+            responseL=spi.write(0x00);
+            calib_data=((responseH&11100000)>>3)|((responseL&00001100)>>2);
+        break;
+        case 2:
+            responseH=spi.write(0x00);
+            responseH=spi.write(0x00);
+            responseH=spi.write(0x00);
+            responseL=spi.write(0x00);
+            calib_data=((responseH&11100000)>>3)|((responseL&00000011));
+        break;
+    }
+    deselect();
+    wait(0.01);
+    set_acc_scale(temp_scale);
+    return calib_data;
+} 
+
+/*-----------------------------------------------------------------------------------------------
+                                SPI SELECT AND DESELECT
+usage: enable and disable mpu6000 communication bus
+-----------------------------------------------------------------------------------------------*/
+void mpu6000_spi::select() {
+    //Set CS low to start transmission (interrupts conversion)
+    cs = 0;
+}
+void mpu6000_spi::deselect() {
+    //Set CS high to stop transmission (restarts conversion)
+    cs = 1;
+}
\ No newline at end of file

diff -r 000000000000 -r 2edbd561b520 MPU6000.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MPU6000.h	Sat Mar 08 12:38:14 2014 +0000
@@ -0,0 +1,162 @@
+/*CODED by Bruno Alfano on 07/03/2014
+www.xene.it
+
+USAGE (example program):
+#include "mbed.h"
+#include "MPU6000.h"        //Include library
+SPI spi(p11, p12, p13);     //define the SPI (mosi, miso, sclk)
+mpu6000_spi imu(spi,p22);   //define the mpu6000 object
+int main(){
+    if(imu.init(1,BITS_DLPF_CFG_5HZ)){  //INIT the mpu6000
+        printf("\nCouldn't initialize MPU6000 via SPI!");
+    }    
+    wait(0.1);    
+    printf("\n\nWHOAMI=%u\n",imu.whoami()); //output the I2C address to know if SPI is working, it should be 104
+    wait(0.1);    
+    printf("\nGyro_scale=%u\n",imu.set_gyro_scale(BITS_FS_2000DPS));    //Set full scale range for gyros
+    wait(1);  
+    printf("\nAcc_scale=%u\n",imu.set_acc_scale(BITS_FS_16G));          //Set full scale range for accs
+    wait(0.1);    
+    while(1) {
+        myled = 1;
+        wait(0.3);
+        myled = 0;
+        wait(0.3);
+        printf("\nT=%.3f",imu.read_temp());
+        printf(" X=%.3f",imu.read_acc(0));  
+        printf(" Y=%.3f",imu.read_acc(1)); 
+        printf(" Z=%.3f",imu.read_acc(2));   
+        printf(" rX=%.3f",imu.read_rot(0));  
+        printf(" rY=%.3f",imu.read_rot(1)); 
+        printf(" rZ=%.3f",imu.read_rot(2));
+    }
+}
+*/
+
+
+#ifndef MPU6000_h
+#define MPU6000_h
+#include "mbed.h"
+
+
+class mpu6000_spi
+{
+    SPI& spi;
+    DigitalOut cs;
+    
+  public:
+    mpu6000_spi(SPI& _spi, PinName _cs);
+    bool init(int sample_rate_div,int low_pass_filter);
+    float read_acc(int axis);
+    float read_rot(int axis);
+    unsigned int set_gyro_scale(int scale);
+    unsigned int set_acc_scale(int scale);
+    int calib_acc(int axis);
+    float read_temp();
+    void select();
+    void deselect();
+    unsigned int whoami();
+    
+    float acc_divider;
+    float gyro_divider;
+    
+  private:
+    PinName _CS_pin;
+    PinName _SO_pin;
+    PinName _SCK_pin;
+    float _error;
+};
+
+#endif
+
+
+
+// MPU6000 registers
+#define MPUREG_XG_OFFS_TC 0x00
+#define MPUREG_YG_OFFS_TC 0x01
+#define MPUREG_ZG_OFFS_TC 0x02
+#define MPUREG_X_FINE_GAIN 0x03
+#define MPUREG_Y_FINE_GAIN 0x04
+#define MPUREG_Z_FINE_GAIN 0x05
+#define MPUREG_XA_OFFS_H 0x06
+#define MPUREG_XA_OFFS_L 0x07
+#define MPUREG_YA_OFFS_H 0x08
+#define MPUREG_YA_OFFS_L 0x09
+#define MPUREG_ZA_OFFS_H 0x0A
+#define MPUREG_ZA_OFFS_L 0x0B
+#define MPUREG_PRODUCT_ID 0x0C
+#define MPUREG_SELF_TEST_X 0x0D
+#define MPUREG_SELF_TEST_Y 0x0E
+#define MPUREG_SELF_TEST_Z 0x0F
+#define MPUREG_SELF_TEST_A 0x10
+#define MPUREG_XG_OFFS_USRH 0x13
+#define MPUREG_XG_OFFS_USRL 0x14
+#define MPUREG_YG_OFFS_USRH 0x15
+#define MPUREG_YG_OFFS_USRL 0x16
+#define MPUREG_ZG_OFFS_USRH 0x17
+#define MPUREG_ZG_OFFS_USRL 0x18
+#define MPUREG_SMPLRT_DIV 0x19
+#define MPUREG_CONFIG 0x1A
+#define MPUREG_GYRO_CONFIG 0x1B
+#define MPUREG_ACCEL_CONFIG 0x1C
+#define MPUREG_INT_PIN_CFG 0x37
+#define MPUREG_INT_ENABLE 0x38
+#define MPUREG_ACCEL_XOUT_H 0x3B
+#define MPUREG_ACCEL_XOUT_L 0x3C
+#define MPUREG_ACCEL_YOUT_H 0x3D
+#define MPUREG_ACCEL_YOUT_L 0x3E
+#define MPUREG_ACCEL_ZOUT_H 0x3F
+#define MPUREG_ACCEL_ZOUT_L 0x40
+#define MPUREG_TEMP_OUT_H 0x41
+#define MPUREG_TEMP_OUT_L 0x42
+#define MPUREG_GYRO_XOUT_H 0x43
+#define MPUREG_GYRO_XOUT_L 0x44
+#define MPUREG_GYRO_YOUT_H 0x45
+#define MPUREG_GYRO_YOUT_L 0x46
+#define MPUREG_GYRO_ZOUT_H 0x47
+#define MPUREG_GYRO_ZOUT_L 0x48
+#define MPUREG_USER_CTRL 0x6A
+#define MPUREG_PWR_MGMT_1 0x6B
+#define MPUREG_PWR_MGMT_2 0x6C
+#define MPUREG_BANK_SEL 0x6D
+#define MPUREG_MEM_START_ADDR 0x6E
+#define MPUREG_MEM_R_W 0x6F
+#define MPUREG_DMP_CFG_1 0x70
+#define MPUREG_DMP_CFG_2 0x71
+#define MPUREG_FIFO_COUNTH 0x72
+#define MPUREG_FIFO_COUNTL 0x73
+#define MPUREG_FIFO_R_W 0x74
+#define MPUREG_WHOAMI 0x75
+
+// Configuration bits MPU6000
+#define BIT_SLEEP 0x40
+#define BIT_H_RESET 0x80
+#define BITS_CLKSEL 0x07
+#define MPU_CLK_SEL_PLLGYROX 0x01
+#define MPU_CLK_SEL_PLLGYROZ 0x03
+#define MPU_EXT_SYNC_GYROX 0x02
+#define BITS_FS_250DPS              0x00
+#define BITS_FS_500DPS              0x08
+#define BITS_FS_1000DPS             0x10
+#define BITS_FS_2000DPS             0x18
+#define BITS_FS_2G                  0x00
+#define BITS_FS_4G                  0x08
+#define BITS_FS_8G                  0x10
+#define BITS_FS_16G                 0x18
+#define BITS_FS_MASK                0x18
+#define BITS_DLPF_CFG_256HZ_NOLPF2  0x00
+#define BITS_DLPF_CFG_188HZ         0x01
+#define BITS_DLPF_CFG_98HZ          0x02
+#define BITS_DLPF_CFG_42HZ          0x03
+#define BITS_DLPF_CFG_20HZ          0x04
+#define BITS_DLPF_CFG_10HZ          0x05
+#define BITS_DLPF_CFG_5HZ           0x06
+#define BITS_DLPF_CFG_2100HZ_NOLPF  0x07
+#define BITS_DLPF_CFG_MASK          0x07
+#define BIT_INT_ANYRD_2CLEAR        0x10
+#define BIT_RAW_RDY_EN              0x01
+#define BIT_I2C_IF_DIS              0x10
+
+#define READ_FLAG   0x80
+
+