driver_max31855.c

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#include "driver_max31855.h"

#define CHIP_NAME                 "Maxim Integrated max31855"       
#define MANUFACTURER_NAME         "Maxim Integrated"                
#define SUPPLY_VOLTAGE_MIN        3.0f                              
#define SUPPLY_VOLTAGE_MAX        3.6f                              
#define MAX_CURRENT               1.5f                              
#define TEMPERATURE_MIN           -20.0f                            
#define TEMPERATURE_MAX           125.0f                            
#define DRIVER_VERSION            1000                              

static uint8_t a_max31855_spi_read(max31855_handle_t *handle, uint32_t *data)
{
    uint8_t buf[4];
    
    if (handle->spi_read_cmd(buf, 4) != 0)          /* spi read */
    {
        return 1;                                   /* return error */
    }
    else
    {
        *data = (((uint32_t)buf[0]) << 24) |
                (((uint32_t)buf[1]) << 16) | 
                (((uint32_t)buf[2]) << 8) |
                (((uint32_t)buf[3]) << 0);          /* get the data */
        
        return 0;                                   /* success return 0 */
    }
}

uint8_t max31855_init(max31855_handle_t *handle)
{
    uint32_t data;
    
    if (handle == NULL)                                                 /* check handle */
    {
        return 2;                                                       /* return error */
    }
    if (handle->debug_print == NULL)                                    /* check debug_print */
    {
        return 3;                                                       /* return error */
    }
    if (handle->spi_init == NULL)                                       /* check spi_init */
    {
        handle->debug_print("max31855: spi_init is null.\n");           /* spi_init is null */
       
        return 3;                                                       /* return error */
    }
    if (handle->spi_deinit == NULL)                                     /* check spi_deinit */
    {
        handle->debug_print("max31855: spi_deinit is null.\n");         /* spi_deinit is null */
       
        return 3;                                                       /* return error */
    }
    if (handle->spi_read_cmd == NULL)                                   /* check spi_read_cmd */
    {
        handle->debug_print("max31855: spi_read_cmd is null.\n");       /* spi_read_cmd is null */
       
        return 3;                                                       /* return error */
    }
    if (handle->delay_ms == NULL)                                       /* check delay_ms */
    {
        handle->debug_print("max31855: delay_ms is null.\n");           /* delay_ms is null */
       
        return 3;                                                       /* return error */
    }
    
    if (handle->spi_init() != 0)                                        /* spi init */
    {
        handle->debug_print("max31855: spi init failed.\n");            /* spi init failed */
        
        return 1;                                                       /* return error */
    }
    if (a_max31855_spi_read(handle, &data) != 0)                        /* read data */
    {
        handle->debug_print("max31855: read data failed.\n");           /* read data failed */
       
        return 1;                                                       /* return error */
    }
    
    handle->fault = 0x00;                                               /* init none */
    handle->inited = 1;                                                 /* flag finish initialization */
    
    return 0;                                                           /* success return 0 */
}

uint8_t max31855_deinit(max31855_handle_t *handle)
{
    uint8_t res;
    
    if (handle == NULL)                                              /* check handle */
    {
        return 2;                                                    /* return error */
    }
    if (handle->inited != 1)                                         /* check handle initialization */
    {
        return 3;                                                    /* return error */
    }
    
    res = handle->spi_deinit();                                      /* spi deinit */
    if (res != 0)                                                    /* check result */
    {
        handle->debug_print("max31855: spi deinit failed.\n");       /* spi deinit failed */
       
        return 1;                                                    /* return error */
    }
    handle->inited = 0;                                              /* flag close */
    
    return 0;                                                        /* success return 0 */
}

uint8_t max31855_get_last_fault(max31855_handle_t *handle, max31855_fault_t *fault)
{
    if (handle == NULL)                                /* check handle */
    {
        return 2;                                      /* return error */
    }
    if (handle->inited != 1)                           /* check handle initialization */
    {
        return 3;                                      /* return error */
    }
    
    *fault = (max31855_fault_t)(handle->fault);        /* set last fault */
    
    return 0;                                          /* success return 0 */
}

uint8_t max31855_read(max31855_handle_t *handle, int16_t *thermocouple_raw, float *thermocouple_temp,
                      int16_t *reference_junction_raw, float *reference_junction_temp)
{
    uint8_t res;
    uint32_t data;
    uint16_t d1;
    uint16_t d0;
    
    if (handle == NULL)                                                       /* check handle */
    {
        return 2;                                                             /* return error */
    }
    if (handle->inited != 1)                                                  /* check handle initialization */
    {
        return 3;                                                             /* return error */
    }
    
    res = a_max31855_spi_read(handle, &data);                                 /* read data */
    if (res != 0)                                                             /* check result */
    {
        handle->debug_print("max31855: read data failed.\n");                 /* read data failed */
       
        return 1;                                                             /* return error */
    }
    d1 = (data >> 16) & 0xFFFFU;                                              /* get d1 */
    d0 = (data >> 0) & 0xFFFFU;                                               /* get d0 */
    if ((d1 & 0x01) != 0)                                                     /* check fault */
    {
        handle->debug_print("max31855: find fault.\n");                       /* find fault */
        handle->fault = d0 & 0x07;                                            /* save fault */
        
        return 4;                                                             /* return error */
    }
    if ((d1 >> 15) != 0)                                                      /* check sign bit */
    {
        *thermocouple_raw = (int16_t)((d1 >> 2) | 0xC000U);                   /* set raw data */
    }
    else
    {
        *thermocouple_raw = (int16_t)(d1 >> 2);                               /* set raw data */
    }
    *thermocouple_temp = (float)(*thermocouple_raw) * 0.25f;                  /* convert data */
    if ((d0 >> 15) != 0)                                                      /* check sign bit */
    {
        *reference_junction_raw = (int16_t)((d1 >> 4) | 0xF000U);             /* set raw data */
    }
    else
    {
        *reference_junction_raw = (int16_t)(d0 >> 4);                         /* set raw data */
    }
    *reference_junction_temp = (float)(*reference_junction_raw) * 0.0625f;    /* convert data */
    
    return 0;                                                                 /* success return 0 */
}

uint8_t max31855_get_reg(max31855_handle_t *handle, uint32_t *data)
{
    if (handle == NULL)                            /* check handle */
    {
        return 2;                                  /* return error */
    }
    if (handle->inited != 1)                       /* check handle initialization */
    {
        return 3;                                  /* return error */
    }
    
    return a_max31855_spi_read(handle, data);      /* read data */
}

uint8_t max31855_info(max31855_info_t *info)
{
    if (info == NULL)                                               /* check handle */
    {
        return 2;                                                   /* return error */
    }
    
    memset(info, 0, sizeof(max31855_info_t));                       /* initialize max31855 info structure */
    strncpy(info->chip_name, CHIP_NAME, 32);                        /* copy chip name */
    strncpy(info->manufacturer_name, MANUFACTURER_NAME, 32);        /* copy manufacturer name */
    strncpy(info->interface, "SPI", 8);                             /* copy interface name */
    info->supply_voltage_min_v = SUPPLY_VOLTAGE_MIN;                /* set minimal supply voltage */
    info->supply_voltage_max_v = SUPPLY_VOLTAGE_MAX;                /* set maximum supply voltage */
    info->max_current_ma = MAX_CURRENT;                             /* set maximum current */
    info->temperature_max = TEMPERATURE_MAX;                        /* set minimal temperature */
    info->temperature_min = TEMPERATURE_MIN;                        /* set maximum temperature */
    info->driver_version = DRIVER_VERSION;                          /* set driver version */
    
    return 0;                                                       /* success return 0 */
}