/**
*********************************************************************
*
* @file    sht_40.c
* @brief   SHT40 driver header file
*
* @date    2024-04-14 19:18:15
* @author  CT
*
* @details Provides functions to interact with the SHT40 temperature and
*          humidity sensor.
*
*************************************************************************
**/

#include <stdint.h>
#include "i2c.h"

#include "sht_40.h"

#define SHT40_ADDRESS       (0x44 << 1)

// REGISTER DEFINES
#define SHT40_HPM           0xFD                   // High precision measurement
#define SHT40_MPM           0xF6                   // Medium precision measurement
#define SHT40_LPM           0xE0                   // Low precision measurement
#define SHT40_READ_SN       0x89                   // Read serial number
#define SHT40_RESET         0x94                   // Soft reset command

static I2C_HandleTypeDef *m_hi2c;
static float m_humidity;
static float m_temperature_C;
static float m_temperature_F;

/**
    @brief Checks if the SHT4X device is on the bus and ready to communicate
    @param hi2c Pointer to a I2C_HandleTypeDef structure that contains
*                the configuration information for the specified I2C.
    @returns 0 on sucess, 1 on failure
**/
uint32_t sht40_init(I2C_HandleTypeDef *hi2c)
{
    uint32_t ret = 0;
    
    // Store I2C interface
    m_hi2c = hi2c;

    // Check that SHT4X is present on the bus
    if(HAL_OK == HAL_I2C_IsDeviceReady(m_hi2c, SHT40_ADDRESS, 3, 100))
    {
        ret = 0;
    }
    else
    {
        ret = 1;
    }

    return ret;
}


/*
 * TODO: Convert to fixed point or floating point
 */
uint32_t sht40_read(void)
{
    uint8_t buf[8];

    buf[0] = SHT40_HPM;
    // high precision measurement can take up to 8.3ms
    HAL_I2C_Master_Transmit(m_hi2c, SHT40_ADDRESS, buf, 1, 10);

    HAL_Delay(10);

    HAL_I2C_Master_Receive(m_hi2c, SHT40_ADDRESS, buf, 6, 10);

    m_temperature_C = (float)((buf[1] + (buf[0] << 8)) / 65534.0f);
    m_temperature_F = m_temperature_C;

    m_temperature_C = (m_temperature_C * 175.0f) - 45.0f;
    m_temperature_F = (m_temperature_F * 315.0f) - 49.0f;

    m_humidity = buf[4] + (buf[3] << 8);
    m_humidity = (125.0f * (float)(m_humidity / (65534.0f))) - 6.0f;

    return (0);
}

float sht40_get_rh(void)
{
	return(m_humidity);
}

float sht40_get_temp_C(void)
{
	return(m_temperature_C);
}


float sht40_get_temp_F(void)
{
	return(m_temperature_F);
}