#include "max31855.h"


// Registers
#define MAX31865_REG_CONFIG 0x00
#define MAX31865_REG_RTD_MSB 0x01
#define MAX31865_REG_RTD_LSB 0x02
#define MAX31865_REG_HFAULT_THRESH_MSB 0x03
#define MAX31865_REG_HFAULT_THRESH_LSB 0x04
#define MAX31865_REG_LFAULT_THRESH_MSB 0x05
#define MAX31865_REG_LFAULT_THRESH_LSB 0x06
#define MAX31865_REG_FAULTSTATUS 0x07

#define MAX31865_REG_WRITE_MODIFIER 0x80

// Fields 
#define MAX31865_CONF_VBIAS (1<<7)
#define MAX31865_CONF_AUTO_CONVERT (1<<6)
#define MAX31865_CONF_1SHOT (1<<5)
#define MAX31865_CONF_3WIRE (1<<4)

#define MAX31865_CONF_FAULT_NOACTION    0b0000
#define MAX31865_CONF_FAULT_AUTODELAY   0b0100
#define MAX31865_CONF_FAULT_MANUALELAY1 0b1000
#define MAX31865_CONF_FAULT_MANUALELAY2 0b1100

#define MAX31865_CONF_FAULT_CLEAR (1<<1)
#define MAX31865_CONF_50_60HZ_FILTER (1<<0)

void max31865_config(SPI_HandleTypeDef* hspi1)
{
    uint8_t config = 0x00;
    config |= MAX31865_CONF_VBIAS;
    config |= MAX31865_CONF_AUTO_CONVERT;
    config |= MAX31865_CONF_FAULT_CLEAR;
    
    uint8_t reg = (MAX31865_REG_WRITE_MODIFIER | MAX31865_REG_CONFIG);
    
    // Assert CS
    HAL_GPIO_WritePin(MAX_CS, 0);
    
    HAL_SPI_Transmit(hspi1, &reg, 1, 100);
    HAL_SPI_Transmit(hspi1, &config, 1, 100);
    
    // Release CS
    HAL_GPIO_WritePin(MAX_CS, 1);
}

void max31865_clear_errors(SPI_HandleTypeDef* hspi1) {
	max31865_config(hspi1);
}

// Grab temperature reading from MAX31865
void max31865_readtemp(SPI_HandleTypeDef* hspi1, therm_settings_t* set, therm_status_t* status)
{

    // TODO: Set RTD ref resistance in set struct

    // Assert CS
    HAL_GPIO_WritePin(MAX_CS, 0);
    
    uint8_t regh = MAX31865_REG_RTD_MSB;
    
    uint8_t rxdatah[1] = {0x00};
    uint8_t rxdatal[1] = {0x00};

    HAL_SPI_Transmit(hspi1, &regh, 1, 100);
    HAL_SPI_Receive(hspi1, rxdatah, 1, 100);
    HAL_SPI_Receive(hspi1, rxdatal, 1, 100);

    // Release CS
    HAL_GPIO_WritePin(MAX_CS, 1);

    // Assemble data array into one var
    uint16_t adc_count = ((rxdatah[0] & 0x7F) << 8) | rxdatal[0];
    
    if((rxdatah[0] & 0x80) && !set->val.ignore_error) {

        // Assert CS
        HAL_GPIO_WritePin(MAX_CS, 0);

        uint8_t reg = MAX31865_REG_FAULTSTATUS;

        uint8_t data[1] = {0x00};

        HAL_SPI_Transmit(hspi1, &reg, 1, 100);
        HAL_SPI_Receive(hspi1, data, 1, 100);

        // Release CS
        HAL_GPIO_WritePin(MAX_CS, 1);

        status->error_code = data[0];

        HAL_Delay(400); // FIXME: remove?
        status->state_resume = status->state;
        status->state = STATE_TC_ERROR;
        status->temp = 0;
        status->temp_frac = 0;
        
    }
    else 
    {
        // Convert to Fahrenheit
        if(set->val.temp_units == TEMP_UNITS_FAHRENHEIT)
        {
        	//use all fixed point math!

        	//convert adc to resistance
        	//Rrtd = adc / range * Rref
        	status->temp = (int32_t) adc_count * 48600L;
        	status->temp /= 32768L;
        	//resistance to temp
        	//(x - in1) * (cal2 - cal1) / (in2 - in1) + cal1
        	status->temp = ((status->temp) - 10000L) * (39200L - 3200L) / (17586L - 10000L) + 3200L;
        	//grab the fraction
        	status->temp_frac = (status->temp / 10) % 10L;
        	//scale back to degrees
        	status->temp = status->temp / 100L;
        	//add in the offset
            status->temp += set->val.temp_offset;
        }

        // Convert to Celsius
        else
        {
        	//use all fixed point math!

        	//convert adc to resistance
        	//Rrtd = adc / range * Rref
        	status->temp = (int32_t) adc_count * 48600L;
        	status->temp /= 32768L;
        	//resistance to temp
        	//(x - in1) * (cal2 - cal1) / (in2 - in1) + cal1
        	status->temp = (((status->temp) - 10000L) * (20000L- 0L)) / (17586L - 10000L) + 0L;
        	//grab the fraction
        	status->temp_frac = (status->temp / 10) % 100L;
        	//scale back to degrees
        	status->temp = status->temp / 100L;
        	//add in the offset
            status->temp += set->val.temp_offset;
        }
    }


}

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