104 lines
2.3 KiB
C
104 lines
2.3 KiB
C
/**
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*********************************************************************
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*
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* @file sht_40.c
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* @brief SHT40 driver header file
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*
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* @date 2024-04-14 19:18:15
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* @author CT
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*
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* @details Provides functions to interact with the SHT40 temperature and
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* humidity sensor.
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*
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*************************************************************************
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**/
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#include <stdint.h>
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#include "i2c.h"
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#include "sht_40.h"
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#define SHT40_ADDRESS (0x44 << 1)
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// REGISTER DEFINES
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#define SHT40_HPM 0xFD // High precision measurement
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#define SHT40_MPM 0xF6 // Medium precision measurement
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#define SHT40_LPM 0xE0 // Low precision measurement
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#define SHT40_READ_SN 0x89 // Read serial number
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#define SHT40_RESET 0x94 // Soft reset command
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static I2C_HandleTypeDef *m_hi2c;
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static float m_humidity;
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static float m_temperature_C;
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static float m_temperature_F;
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/**
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@brief Checks if the SHT4X device is on the bus and ready to communicate
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@param hi2c Pointer to a I2C_HandleTypeDef structure that contains
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* the configuration information for the specified I2C.
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@returns 0 on sucess, 1 on failure
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**/
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uint32_t sht40_init(I2C_HandleTypeDef *hi2c)
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{
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uint32_t ret = 0;
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// Store I2C interface
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m_hi2c = hi2c;
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// Check that SHT4X is present on the bus
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if(HAL_OK == HAL_I2C_IsDeviceReady(m_hi2c, SHT40_ADDRESS, 3, 100))
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{
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ret = 0;
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}
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else
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{
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ret = 1;
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}
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return ret;
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}
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/*
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*
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*/
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uint32_t sht40_read(void)
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{
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uint8_t buf[8];
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buf[0] = SHT40_HPM;
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// high precision measurement can take up to 8.3ms
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HAL_I2C_Master_Transmit(m_hi2c, SHT40_ADDRESS, buf, 1, 10);
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HAL_Delay(10);
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HAL_I2C_Master_Receive(m_hi2c, SHT40_ADDRESS, buf, 6, 10);
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m_temperature_C = (float)((buf[1] + (buf[0] << 8)) / 65534.0f);
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m_temperature_F = m_temperature_C;
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m_temperature_C = (m_temperature_C * 175.0f) - 45.0f;
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m_temperature_F = (m_temperature_F * 315.0f) - 49.0f;
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m_humidity = buf[4] + (buf[3] << 8);
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m_humidity = (125.0f * (float)(m_humidity / (65534.0f))) - 6.0f;
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return (0);
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}
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float sht40_get_rh(void)
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{
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return(m_humidity);
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}
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float sht40_get_temp_C(void)
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{
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return(m_temperature_C);
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}
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float sht40_get_temp_F(void)
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{
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return(m_temperature_F);
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}
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