Merge sht4x_minimal

fw/Core/Inc/crc8.h

@@ -0,0 +1,22 @@
+/*
+ * crc.h
+ *
+ *  Created on: Jun 9, 2021
+ *      Author: user
+ */
+
+#ifndef INC_CRC8_H_
+#define INC_CRC8_H_
+
+#include "stdint.h"
+
+/*
+ * Definitions & macros
+ */
+
+#define CRC8_POLYNOMIAL 0x31
+#define CRC8_INIT 0xFF
+
+uint8_t crc8_calculate(const uint8_t *data, uint16_t count);
+
+#endif /* INC_CRC8_H_ */

fw/Core/Inc/i2c.h

@@ -0,0 +1,46 @@
+/*
+ * i2c.h
+ *
+ *  Created on: Jun 8, 2021
+ *      Author: user
+ */
+
+#ifndef INC_I2C_H_
+#define INC_I2C_H_
+
+#include "stdint.h"
+#include "stm32l0xx_ll_i2c.h"
+
+/*
+ * Defines & macros
+ */
+
+#define NULL 0
+
+/*
+ * Return values for I2C functions
+ */
+
+#define I2C_OK 0
+#define I2C_ERROR -1 // generic error
+#define I2C_ERROR_NACK -2 // NACK was received during transfer
+#define I2C_ERROR_TX_INCOMPLETE -3 // number of TXed bytes != buffer length
+#define I2C_ERROR_RX_INCOMPLETE -4 // number of RXed bytes != buffer length
+
+/*
+ * Type definitions
+ */
+
+typedef struct {
+	I2C_TypeDef *i2c;
+} i2c_context_t;
+
+/*
+ * Function declarations
+ */
+
+int i2c_init(i2c_context_t *context);
+int i2c_transmit(uint8_t address, uint8_t *buffer, int len);
+int i2c_receive(uint8_t address, uint8_t *buffer, int len);
+
+#endif /* INC_I2C_H_ */

fw/Core/Inc/main.h

@@ -48,6 +48,8 @@ extern "C" {
 
 /* Private includes ----------------------------------------------------------*/
 /* USER CODE BEGIN Includes */
+#include "i2c.h"
+#include "sht4x.h"
 /* USER CODE END Includes */
 
 /* Exported types ------------------------------------------------------------*/

fw/Core/Inc/sht4x.h

@@ -0,0 +1,57 @@
+/*
+ * 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 {
+	START_MEAS_HIGH_PRECISION = 0xFD,
+	START_MEAS_MEDIUM_PRECISION = 0xF6,
+	START_MEAS_LOW_PRECISION = 0xE0,
+	READ_SERIAL = 0x89,
+	SOFT_RESET = 0x94,
+	HEATER_200_mW_1_s = 0x39,
+	HEATER_200_mW_01_s = 0x32,
+	HEATER_110_mW_1_s = 0x2F,
+	HEATER_110_mW_01_s = 0x24,
+	HEATER_20_mW_1_s = 0x1E,
+	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(int *temperature, int *relative_humidity);
+
+#endif /* INC_SHT4X_H_ */

fw/Core/Src/crc8.c

@@ -0,0 +1,28 @@
+/*
+ * crc.c
+ *
+ *  Created on: Jun 9, 2021
+ *      Author: user
+ */
+
+#include "crc8.h"
+
+/* Stolen from Sensirion SCD4x datasheet, section 3.11 */
+uint8_t crc8_calculate(const uint8_t *data, uint16_t count)
+{
+	uint16_t current_byte;
+	uint8_t crc = CRC8_INIT;
+	uint8_t crc_bit;
+	/* calculates 8-Bit checksum with given polynomial */
+	for (current_byte = 0; current_byte < count; ++current_byte) {
+		crc ^= (data[current_byte]);
+		for(crc_bit = 8; crc_bit > 0; --crc_bit) {
+			if (crc & 0x80) {
+				crc =(crc << 1) ^ CRC8_POLYNOMIAL;
+			} else {
+				crc = (crc << 1);
+			}
+		}
+	}
+	return crc;
+}

fw/Core/Src/i2c.c

@@ -0,0 +1,64 @@
+/*
+ * i2c.c
+ *
+ *  Created on: Jun 8, 2021
+ *      Author: user
+ */
+
+#include "i2c.h"
+
+i2c_context_t *i2c_context;
+
+int i2c_init(i2c_context_t *context)
+{
+	if (context == NULL) {
+		return I2C_ERROR;
+	}
+	i2c_context = context;
+	return I2C_OK;
+}
+
+int i2c_transmit(uint8_t address, uint8_t *buffer, int len)
+{
+	LL_I2C_HandleTransfer(i2c_context->i2c, address, LL_I2C_ADDRSLAVE_7BIT, len,
+				LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_WRITE);
+	int i = 0;
+	// Autoend mode will raise STOP flag if NACK is detected
+	// (or if desired number of bytes is transmitted)
+	while (!LL_I2C_IsActiveFlag_STOP(i2c_context->i2c)) {
+		if (LL_I2C_IsActiveFlag_TXE(i2c_context->i2c)) {
+			if (i < len) {
+				LL_I2C_TransmitData8(i2c_context->i2c, buffer[i++]);
+			}
+		}
+	}
+	LL_I2C_ClearFlag_STOP(i2c_context->i2c);
+	if (LL_I2C_IsActiveFlag_NACK(i2c_context->i2c)) {
+		return I2C_ERROR_NACK;
+	}
+	if (len != i) {
+		// this will probably never happen, as NACK flag
+		// is raised everytime len != number of TXed bytes
+		return I2C_ERROR_TX_INCOMPLETE;
+	}
+	return I2C_OK;
+}
+
+int i2c_receive(uint8_t address, uint8_t *buffer, int len)
+{
+	LL_I2C_HandleTransfer(i2c_context->i2c, address, LL_I2C_ADDRSLAVE_7BIT, len,
+				LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_READ);
+	int i = 0;
+	while (!LL_I2C_IsActiveFlag_STOP(i2c_context->i2c)) {
+		if (LL_I2C_IsActiveFlag_RXNE(i2c_context->i2c)) {
+			if (i < len) {
+				buffer[i++] = LL_I2C_ReceiveData8(i2c_context->i2c);
+			}
+		}
+	}
+	LL_I2C_ClearFlag_STOP(i2c_context->i2c);
+	if (len != i) {
+		return I2C_ERROR_RX_INCOMPLETE;
+	}
+	return I2C_OK; // TODO error detection
+}

fw/Core/Src/main.c

@@ -98,7 +98,10 @@ int main(void)
   /* USER CODE BEGIN 2 */
   LL_I2C_Enable(I2C1);
   LL_LPUART_Enable(LPUART1);
-  /* LED PWM context */
+  /* I2C context init (for SHT4x and SCD4x) */
+  i2c_context_t i2c_context;
+  i2c_context.i2c = I2C1;
+  i2c_init(&i2c_context);
 
   /* USER CODE END 2 */
 
@@ -107,13 +110,17 @@ int main(void)
   uint8_t uart_data_dummy = 0;
   while (1)
   {
+	  /* RS485 test */
 	  LL_LPUART_SetDESignalPolarity(LPUART1, 1);
 	  LL_LPUART_TransmitData8(LPUART1, uart_data_dummy);
 	  uart_data_dummy++;
 
+	  /* SHT41 measurement */
+	  int T, RH;
+	  sht4x_measure(&T, &RH);
+
 	  LL_mDelay(1000);
     /* USER CODE END WHILE */
-
     /* USER CODE BEGIN 3 */
   }
   /* USER CODE END 3 */
@@ -216,7 +223,6 @@ static void MX_I2C1_Init(void)
   LL_I2C_Init(I2C1, &I2C_InitStruct);
   LL_I2C_SetOwnAddress2(I2C1, 0, LL_I2C_OWNADDRESS2_NOMASK);
   /* USER CODE BEGIN I2C1_Init 2 */
-
   /* USER CODE END I2C1_Init 2 */
 
 }

fw/Core/Src/sht4x.c

@@ -0,0 +1,53 @@
+/*
+ * sht4x.c
+ *
+ *  Created on: Jun 8, 2021
+ *      Author: user
+ */
+
+#include "sht4x.h"
+
+int8_t sht4x_send_cmd(sht4x_cmd_t cmd)
+{
+
+}
+
+int8_t sht4x_read_data(uint8_t *buffer, int len)
+{
+
+}
+
+int8_t sht4x_measure(int *temperature, int *relative_humidity)
+{
+	uint8_t buffer[32];
+	int result;
+
+	// start measurement
+	buffer[0] = START_MEAS_HIGH_PRECISION;
+	result = i2c_transmit(SHT4X_I2C_ADDRESS<<1, buffer, 1);
+	if (result != I2C_OK) {
+		return SHT4X_ERROR;
+	}
+	LL_mDelay(100); // 10 ms should be enough
+	// read out
+	result = i2c_receive(SHT4X_I2C_ADDRESS<<1, buffer, 6);
+	if (result != I2C_OK) {
+		return SHT4X_ERROR;
+	}
+	// TODO checksum
+	// Convert to T and RH; taken directly from pseudocode in SHT4x datasheet, page 3
+	uint32_t t_ticks = (buffer[0] << 8) + buffer[1];
+	uint32_t rh_ticks = (buffer[3] << 8) + buffer[4];
+	int t_degC = -45 + 175 * t_ticks / 65535;
+	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;
+}