File content as of revision 0:768d2e151834:

/*CODED by Qiyong Mu on 21/06/2014

*/

#include <mbed.h>
#include <mpu9250.h>

mpu9250_spi::mpu9250_spi(SPI& _spi, PinName _cs) : spi(_spi), cs(_cs) {}

unsigned int mpu9250_spi::WriteReg( uint8_t WriteAddr, uint8_t WriteData )
{
    unsigned int temp_val;
    select();
    spi.write(WriteAddr);
    temp_val=spi.write(WriteData);
    deselect();
    wait_us(50);
    return temp_val;
}
void mpu9250_spi::ReadRegs( unsigned int ReadAddr, unsigned int *ReadBuf, unsigned int Bytes )
{
    unsigned int  i = 0;

    select();
    spi.write(ReadAddr | READ_FLAG);
    for(i=0; i<Bytes; i++)
        ReadBuf[i] = spi.write(0x00);
    deselect();
    wait_us(50);
}

/*
void mpu9250_spi::ReadReg( u8 ReadAddr, u8 *ReadData )
{
    select();
    response=spi.write(MPUREG_USER_CTRL);
    response=spi.write(BIT_I2C_IF_DIS);
    deselect();
  IMU_CSM = 0;
  SPI_WriteByte(SPIx, 0x80 | ReadAddr);
  *ReadData = SPI_ReadByte(SPIx);
  IMU_CSM = 1;
}
*/
/*-----------------------------------------------------------------------------------------------
                                    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
-----------------------------------------------------------------------------------------------*/
#define MPU_InitRegNum 10

bool mpu9250_spi::init(int sample_rate_div,int low_pass_filter){
    uint8_t i = 0;
    uint8_t MPU_Init_Data[MPU_InitRegNum][2] = {
        {0x80, MPUREG_PWR_MGMT_1},     // Reset Device
        {0x01, MPUREG_PWR_MGMT_1},     // Clock Source
        {0x00, MPUREG_PWR_MGMT_2},     // Enable Acc & Gyro
        {0x07, MPUREG_CONFIG},         //
        {0x18, MPUREG_GYRO_CONFIG},    // +-2000dps
        {0x08, MPUREG_ACCEL_CONFIG},   // +-4G
        {0x00, MPUREG_ACCEL_CONFIG_2}, // Set Acc Data Rates
        {0x30, MPUREG_INT_PIN_CFG},    //
        {0x40, MPUREG_I2C_MST_CTRL},   // I2C Speed 348 kHz
        {0x20, MPUREG_USER_CTRL},      // Enable AUX
    };
    spi.format(8,0);
    spi.frequency(1000000);

    for(i=0; i<MPU_InitRegNum; i++) {
        WriteReg(MPU_Init_Data[i][1], MPU_Init_Data[i][0]);
    }
    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 mpu9250_spi::set_acc_scale(int scale){
    unsigned int temp_scale;
    WriteReg(MPUREG_ACCEL_CONFIG, scale);
    
    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;   
    }
    temp_scale=WriteReg(MPUREG_ACCEL_CONFIG|READ_FLAG, 0x00);
    
    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 mpu9250_spi::set_gyro_scale(int scale){
    unsigned int temp_scale;
    WriteReg(MPUREG_GYRO_CONFIG, scale);
    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;   
    }
    temp_scale=WriteReg(MPUREG_GYRO_CONFIG|READ_FLAG, 0x00);
    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
mpu9250 which should be 104 when in SPI mode.
returns the I2C address (104)
-----------------------------------------------------------------------------------------------*/
unsigned int mpu9250_spi::whoami(){
    unsigned int response;
    response=WriteReg(MPUREG_WHOAMI|READ_FLAG, 0x00);
    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 mpu9250_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 mpu9250_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 mpu9250_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 mpu9250_spi::calib_acc(int axis){
    uint8_t responseH,responseL,calib_data;
    int temp_scale;
    //READ CURRENT ACC SCALE
    temp_scale=WriteReg(MPUREG_ACCEL_CONFIG|READ_FLAG, 0x00);
    set_acc_scale(BITS_FS_8G);
    //ENABLE SELF TEST
    temp_scale=WriteReg(MPUREG_ACCEL_CONFIG, 0x80>>axis);

    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 mpu9250 communication bus
-----------------------------------------------------------------------------------------------*/
void mpu9250_spi::select() {
    //Set CS low to start transmission (interrupts conversion)
    cs = 0;
}
void mpu9250_spi::deselect() {
    //Set CS high to stop transmission (restarts conversion)
    cs = 1;
}