mpl3115a2.c

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#include "mpl3115a2.h"
 
static I2C_HandleTypeDef *i2c;
 
static uint16_t devAddr;
 
HAL_StatusTypeDef MPL3115A2_Init(I2C_HandleTypeDef *hi2c, uint16_t devAddress)
{
    HAL_StatusTypeDef halStatus = HAL_OK;
    uint8_t whoAmI = 0x00;
    uint8_t standbyCmd = 0x00;
    uint8_t configData[2];
 
    i2c = hi2c;
    devAddr = devAddress;
 
    do {
        halStatus = HAL_I2C_IsDeviceReady(i2c, devAddr, 5, 10);
        if (halStatus != HAL_OK) {
            reset_I2C();
        }
    } while (halStatus != HAL_OK);
 
    if (halStatus == HAL_OK) {
        halStatus = HAL_I2C_Mem_Read(i2c, devAddr, MPL3115A2_WHOAMI,
                I2C_MEMADD_SIZE_8BIT, &whoAmI, 1, 1000);
 
        if (halStatus == HAL_OK && whoAmI != 0xC4) {
            Error_Handler();
        }
    }
 
    if (halStatus == HAL_OK) {
        /* Enter standby before changing sensor configuration registers. */
        halStatus = HAL_I2C_Mem_Write(i2c, devAddr, MPL3115A2_CTRL_REG1,
                I2C_MEMADD_SIZE_8BIT, &standbyCmd, 1, 100);
    }
 
    if (halStatus == HAL_OK) {
        /* Enable pressure and temperature data-ready event flags. */
        configData[0] = MPL3115A2_PT_DATA_CFG;
        configData[1] = MPL3115A2_PT_DATA_CFG_TDEFE |
                MPL3115A2_PT_DATA_CFG_PDEFE |
                MPL3115A2_PT_DATA_CFG_DREM;
        halStatus = HAL_I2C_Master_Transmit(i2c, devAddr, configData, 2,
                HAL_MAX_DELAY);
    }
 
    if (halStatus == HAL_OK) {
        /* Use barometer mode, OSR=128, and active mode. */
        configData[0] = MPL3115A2_CTRL_REG1;
        configData[1] = MPL3115A2_CTRL_REG1_OS128 | MPL3115A2_CTRL_REG1_SBYB;
        halStatus = HAL_I2C_Master_Transmit(i2c, devAddr, configData, 2,
                HAL_MAX_DELAY);
    }
 
    return halStatus;
}
 
HAL_StatusTypeDef MPL3115A2_GetStatus(uint8_t *retVal)
{
    HAL_StatusTypeDef halStatus = HAL_OK;
    uint8_t data;
 
    halStatus = HAL_I2C_Mem_Read(i2c, devAddr, MPL3115A2_REGISTER_STATUS,
            I2C_MEMADD_SIZE_8BIT, &data, 1, HAL_MAX_DELAY);
 
    *retVal = data;
 
    return halStatus;
}
 
HAL_StatusTypeDef MPL3115A2_ReadTemperature(float *celsius)
{
    uint8_t rawData[2];
    int16_t tempRaw;
    HAL_StatusTypeDef halStatus = HAL_OK;
 
    halStatus = HAL_I2C_Mem_Read(i2c, devAddr, MPL3115A2_REGISTER_TEMP_MSB,
            I2C_MEMADD_SIZE_8BIT, rawData, 2, HAL_MAX_DELAY);
 
    if (halStatus == HAL_OK) {
        /* OUT_T_MSB:OUT_T_LSB is a signed Q8.4 value (1/256 C per LSB of the pair). */
        tempRaw = (int16_t)((rawData[0] << 8) | rawData[1]);
        *celsius = (float)tempRaw / 256.0f;
    } else {
        *celsius = -99.99f;
    }
 
    return halStatus;
}
 
HAL_StatusTypeDef MPL3115A2_ReadPressure(float *pressure_inHg)
{
    uint8_t pressureData[3];
    uint32_t pressureQ18_2;
    float pressurePa;
    HAL_StatusTypeDef halStatus = HAL_OK;
 
    halStatus = HAL_I2C_Mem_Read(i2c, devAddr,
            MPL3115A2_REGISTER_PRESSURE_MSB, I2C_MEMADD_SIZE_8BIT,
            pressureData, 3, HAL_MAX_DELAY);
 
    if (halStatus == HAL_OK) {
        /*
         * Pressure is returned as a 20-bit unsigned Q18.2 value left-aligned
         * across OUT_P_MSB, OUT_P_CSB, and OUT_P_LSB.
         */
        pressureQ18_2 = ((uint32_t)pressureData[0] << 16) |
                ((uint32_t)pressureData[1] << 8) |
                (uint32_t)pressureData[2];
        pressureQ18_2 >>= 4;
 
        pressurePa = (float)pressureQ18_2 / 4.0f;
        *pressure_inHg = pressurePa / 3386.389f;
    } else {
        *pressure_inHg = -99.99f;
    }
 
    return halStatus;
}