Moved I2C related functions to i2c.c

fw/Core/Inc/i2c.h

@@ -0,0 +1,44 @@
+/*
+ * 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
+
+/*
+ * 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

@@ -49,6 +49,7 @@ extern "C" {
 /* Private includes ----------------------------------------------------------*/
 /* USER CODE BEGIN Includes */
 #include "led.h"
+#include "i2c.h"
 #include "sht4x.h"
 /* USER CODE END Includes */
 

fw/Core/Inc/sht4x.h

@@ -10,6 +10,7 @@
 
 #include "stdint.h"
 #include "stm32l0xx_ll_i2c.h"
+#include "i2c.h"
 
 /*
  * Defines & macros
@@ -18,12 +19,15 @@
 #define SHT4X_I2C_ADDRESS 0x44
 
 /*
- * Data types
+ * Return values
  */
 
-typedef struct {
+#define SHT4X_OK 0
-	I2C_TypeDef *i2c;
+#define SHT4X_ERROR -1 // generic error
-} sht4x_context_t;
+
+/*
+ * Data types
+ */
 
 typedef enum {
 	START_MEAS_HIGH_PRECISION = 0xFD,
@@ -43,7 +47,6 @@ typedef enum {
  * Function prototypes
  */
 
-int sht4x_init(sht4x_context_t *context);
 int sht4x_send_cmd(sht4x_cmd_t cmd);
 int sht4x_read_data(uint8_t *buffer, int len);
 int sht4x_measure(int *temperature, int *relative_humidity);

fw/Core/Src/i2c.c

@@ -0,0 +1,55 @@
+/*
+ * 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_ADDRESSING_MODE_7BIT, len,
+			LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_WRITE);
+	int i = 0;
+	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;
+	}
+	return I2C_OK;
+}
+
+int i2c_receive(uint8_t address, uint8_t *buffer, int len)
+{
+	LL_I2C_HandleTransfer(i2c_context->i2c, address, LL_I2C_ADDRESSING_MODE_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);
+
+	return I2C_OK; // TODO error detection
+}

fw/Core/Src/main.c

@@ -108,10 +108,10 @@ int main(void)
   led_context.blue_led_pin = LED_B_Pin;
   led_init(&led_context, 50, 1000);
   led_set_color(80, 0, 0);
-  /* SHT4x context init */
+  /* I2C context init (for SHT4x and SCD4x) */
-  sht4x_context_t sht4x_context;
+  i2c_context_t i2c_context;
-  sht4x_context.i2c = I2C1;
+  i2c_context.i2c = I2C1;
-  sht4x_init(&sht4x_context);
+  i2c_init(&i2c_context);
   /* USER CODE END 2 */
 
   /* Infinite loop */

fw/Core/Src/sht4x.c

@@ -7,43 +7,6 @@
 
 #include "sht4x.h"
 
-sht4x_context_t *sht4x_context;
-
-int sht4x_init(sht4x_context_t *context)
-{
-	sht4x_context = context;
-}
-
-void i2c_transmit(uint8_t address, uint8_t *buffer, int len)
-{
-	LL_I2C_HandleTransfer(sht4x_context->i2c, address, LL_I2C_ADDRESSING_MODE_7BIT, len,
-			LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_WRITE);
-	int i = 0;
-	while (!LL_I2C_IsActiveFlag_STOP(sht4x_context->i2c)) {
-		if (LL_I2C_IsActiveFlag_TXE(sht4x_context->i2c)) {
-			if (i < len) {
-				LL_I2C_TransmitData8(sht4x_context->i2c, buffer[i++]);
-			}
-		}
-	}
-	LL_I2C_ClearFlag_STOP(sht4x_context->i2c);
-}
-
-void i2c_receive(uint8_t address, uint8_t *buffer, int len)
-{
-	LL_I2C_HandleTransfer(sht4x_context->i2c, address, LL_I2C_ADDRESSING_MODE_7BIT, len,
-				LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_READ);
-	int i = 0;
-	while (!LL_I2C_IsActiveFlag_STOP(sht4x_context->i2c)) {
-		if (LL_I2C_IsActiveFlag_RXNE(sht4x_context->i2c)) {
-			if (i < len) {
-				buffer[i++] = LL_I2C_ReceiveData8(sht4x_context->i2c);
-			}
-		}
-	}
-	LL_I2C_ClearFlag_STOP(sht4x_context->i2c);
-}
-
 int sht4x_send_cmd(sht4x_cmd_t cmd)
 {
 
@@ -57,17 +20,22 @@ int sht4x_read_data(uint8_t *buffer, int len)
 int sht4x_measure(int *temperature, int *relative_humidity)
 {
 	uint8_t buffer[32];
+	int result;
 
 	// start measurement
 	buffer[0] = START_MEAS_HIGH_PRECISION;
-	i2c_transmit(SHT4X_I2C_ADDRESS, buffer, 1);
+	result = i2c_transmit(SHT4X_I2C_ADDRESS, buffer, 1);
-	// delay TODO
+	if (result != I2C_OK) {
-	volatile int j,k;
+		return SHT4X_ERROR;
-	for (j = 0; j < 100000; j++);
+	}
+	// busy delay (LL_mDelay uses SysTick which doesn't work at the moment) TODO
+	for (volatile int j = 0; j < 100000; j++);
 	// read out
-	i2c_receive(SHT4X_I2C_ADDRESS, buffer, 6);
+	result = i2c_receive(SHT4X_I2C_ADDRESS, buffer, 6);
-	// TODO
+	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];
 	uint32_t rh_ticks = (buffer[3] << 8) + buffer[4];
 	int t_degC = -45 + 175 * t_ticks / 65535;
@@ -80,4 +48,6 @@ int sht4x_measure(int *temperature, int *relative_humidity)
 	}
 	*temperature = t_degC;
 	*relative_humidity = rh_pRH;
+
+	return SHT4X_OK;
 }