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Added sht4x library

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This commit is contained in:
Jan Mrna
2022-06-14 21:15:22 +02:00
parent 990e1ae908
commit bb9075f7ba
7 changed files with 65 additions and 139 deletions
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57
fw/Core/Inc/sht4x.h
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@@ -1,57 +0,0 @@
/*
* sht4x.h
*
* Created on: Jun 8, 2021
* Author: user
*/
#ifndef INC_SHT4X_H_
#define INC_SHT4X_H_
#include "stdint.h"
#include "stm32l0xx_ll_i2c.h"
#include "stm32l0xx_ll_utils.h"
#include "i2c.h"
#include "crc8.h"
/*
* Defines & macros
*/
#define SHT4X_I2C_ADDRESS 0x44
/*
* Return values
*/
#define SHT4X_OK 0
#define SHT4X_ERROR -1 // generic error
#define SHT4X_CRC8_ERROR -2 // checksum failed
/*
* Data types
*/
typedef enum {
SHT4X_START_MEAS_HIGH_PRECISION = 0xFD,
SHT4X_START_MEAS_MEDIUM_PRECISION = 0xF6,
SHT4X_START_MEAS_LOW_PRECISION = 0xE0,
SHT4X_READ_SERIAL = 0x89,
SHT4X_SOFT_RESET = 0x94,
SHT4X_HEATER_200_mW_1_s = 0x39,
SHT4X_HEATER_200_mW_01_s = 0x32,
SHT4X_HEATER_110_mW_1_s = 0x2F,
SHT4X_HEATER_110_mW_01_s = 0x24,
SHT4X_HEATER_20_mW_1_s = 0x1E,
SHT4X_HEATER_20_mW_01_s = 0x15
} sht4x_cmd_t;
/*
* Function prototypes
*/
int8_t sht4x_send_cmd(sht4x_cmd_t cmd);
int8_t sht4x_read_data(uint8_t *buffer, int len);
int8_t sht4x_measure(int16_t *temperature, uint16_t *relative_humidity);
#endif /* INC_SHT4X_H_ */

34
fw/Core/Src/main.c
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@@ -168,6 +168,40 @@ void CO2_to_color(uint16_t co2, uint16_t co2_limit_yellow, uint16_t co2_limit_re
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
/*
* Functions for SHT4x lib
*/
int8_t sht4x_i2c_transmit(uint8_t address, uint8_t *buffer, int len)
{
i2c_transmit(address, buffer, len);
}
int8_t sht4x_i2c_receive(uint8_t address, uint8_t *buffer, int len)
{
i2c_receive(address, buffer, len);
}
uint8_t sensirion_crc8_calculate(const uint8_t *data, uint16_t count)
{
crc8_calculate(data, count);
}
int8_t sht4x_disable_interrupts(void)
{
uart_disable_interrupts();
}
int8_t sht4x_enable_interrupts(void)
{
uart_enable_interrupts();
}
void delay_ms(int delay_ms)
{
LL_mDelay(delay_ms);
}
/* USER CODE END 0 */
/**

67
fw/Core/Src/sht4x.c
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@@ -1,67 +0,0 @@
/*
* sht4x.c
*
* Created on: Jun 8, 2021
* Author: user
*/
#include "sht4x.h"
#include "main.h" /* for uart_disable_interrupts() */
int8_t sht4x_send_cmd(sht4x_cmd_t cmd)
{
return SHT4X_OK;
}
int8_t sht4x_read_data(uint8_t *buffer, int len)
{
return SHT4X_OK;
}
int8_t sht4x_measure(int16_t *temperature, uint16_t *relative_humidity)
{
uint8_t buffer[32];
int result;
/* start measurement */
buffer[0] = SHT4X_START_MEAS_HIGH_PRECISION;
/* disable interrupts to prevent modbus/i2c conflict */
uart_disable_interrupts();
result = i2c_transmit(SHT4X_I2C_ADDRESS<<1, buffer, 1);
uart_enable_interrupts();
if (result != I2C_OK) {
return SHT4X_ERROR;
}
LL_mDelay(10); /* 10 ms should be enough */
/* read out */
uart_disable_interrupts();
result = i2c_receive(SHT4X_I2C_ADDRESS<<1, buffer, 6);
uart_enable_interrupts();
if (result != I2C_OK) {
return SHT4X_ERROR;
}
/* Convert to T and RH; taken directly from pseudocode in SHT4x datasheet, page 3 */
uint32_t t_ticks = (buffer[0] << 8) + buffer[1];
uint8_t t_crc = buffer[2];
uint32_t rh_ticks = (buffer[3] << 8) + buffer[4];
uint8_t rh_crc = buffer[5];
/* check CRC-8 checksum */
uint8_t crc_correct = crc8_calculate(buffer, 2) == t_crc;
crc_correct &= crc8_calculate(buffer + 3, 2) == rh_crc;
if (!crc_correct) {
return SHT4X_CRC8_ERROR;
}
/* copy data to output variables */
int t_degC = -450 + 10 * 175 * t_ticks / 65535; /* temperature * 10 */
int rh_pRH = -6 + 125 * rh_ticks / 65535;
if (rh_pRH > 100) {
rh_pRH = 100;
}
if (rh_pRH < 0) {
rh_pRH = 0;
}
*temperature = t_degC;
*relative_humidity = rh_pRH;
return SHT4X_OK;
}