Add SPI interface functions

weather-sensor/firmware/bme280_interface.c

 #include <avr/io.h>
 #include <util/delay.h>
 
+#include "spi.h"
 #include "bme280.h"
 #include "bme280_interface.h"
 
 	/* unused parameters */
 	(void)dev_id;
 
-	/* SPI routine */
-
-	/* TODO pack into spi byte transfer function */
-	BME_CSN_PORT &= ~(1<<BME_CSN_PIN); // Start the transmission
-	SPDR = reg_addr;
-	while(!(SPSR & (1<<SPIF))); // Wait for transmission complete
+	SPI_Start_Transmission(&BME_CSN_PORT, BME_CSN_PIN);
+	SPI_Transfer_Byte(reg_addr);
 
 	for (uint16_t i = 0; i < len; i ++)
 	{
-		SPDR = 0x0; /* value doesn't matter */
-		while(!(SPSR & (1<<SPIF))); // Wait for transmission complete
-		reg_data[i] = SPDR;
+		reg_data[i] = SPI_Transfer_Byte(0x0); /* Value to send doesn't matter */
 	}
-	BME_CSN_PORT |= (1<<BME_CSN_PIN); // Stop the transmission
+	SPI_Stop_Transmission(&BME_CSN_PORT, BME_CSN_PIN);
 
 	return rslt;
 }
 	(void)dev_id;
 
 	/* SPI routine */
-	BME_CSN_PORT &= ~(1<<BME_CSN_PIN); // Start the transmission
-	SPDR = reg_addr;
-	while(!(SPSR & (1<<SPIF))); // Wait for transmission complete
+	SPI_Start_Transmission(&BME_CSN_PORT, BME_CSN_PIN);
+	SPI_Transfer_Byte(reg_addr);
 
 	for (uint16_t i = 0; i < len; i ++)
 	{
-		SPDR = reg_data[i]; /* value doesn't matter */
-		while(!(SPSR & (1<<SPIF))); // Wait for transmission complete
+		SPI_Transfer_Byte(reg_data[i]);
 	}
-	BME_CSN_PORT |= (1<<BME_CSN_PIN); // Stop the transmission
+	SPI_Stop_Transmission(&BME_CSN_PORT, BME_CSN_PIN);
 
 	return rslt;
 }

weather-sensor/firmware/makefile

 flash: main.hex
 	sudo avrdude -c avr109 -b 57600 -P /dev/ttyACM0 -p m32u4 -v -U flash:w:main.hex
 
-main: main.c nrf24l01.c nrf24l01.h nrf24l01_definitions.h uart_debug.c uart_debug.h bme280_interface.c bme280_interface.h BME280_driver/bme280.c BME280_driver/bme280.h
-	avr-gcc main.c nrf24l01.c bme280_interface.c BME280_driver/bme280.c uart_debug.c  -I BME280_driver -o main -mmcu=atmega32u4 -Os -Wall -Wextra -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -DF_CPU=8000000UL -D BME280_32BIT_ENABLE
+main: main.c spi.c spi.h nrf24l01.c nrf24l01.h nrf24l01_definitions.h uart_debug.c uart_debug.h bme280_interface.c bme280_interface.h BME280_driver/bme280.c BME280_driver/bme280.h
+	avr-gcc main.c spi.c nrf24l01.c bme280_interface.c BME280_driver/bme280.c uart_debug.c  -I BME280_driver -o main -mmcu=atmega32u4 -Os -Wall -Wextra -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -DF_CPU=8000000UL -D BME280_32BIT_ENABLE
 
 main.hex: main
 	avr-objcopy -O ihex -R .eeprom main main.hex

weather-sensor/firmware/spi.c

+#include <avr/io.h>
+
+void SPI_Start_Transmission(volatile uint8_t *port, uint8_t pinNumber)
+{
+	*port &= ~(1<<pinNumber);
+}
+
+uint8_t SPI_Transfer_Byte(uint8_t byteToSend)
+{
+	SPDR = byteToSend;
+	while(!(SPSR & (1<<SPIF))); // Wait for transmission complete
+	return SPDR;
+}
+
+void SPI_Stop_Transmission(volatile uint8_t *port, uint8_t pinNumber)
+{
+	*port |= (1<<pinNumber); // Stop the transmission
+}

weather-sensor/firmware/spi.h

+#ifndef SPI_H
+#define SPI_H
+
+void SPI_Start_Transmission(volatile uint8_t *port, uint8_t pinNumber);
+uint8_t SPI_Transfer_Byte(uint8_t byte);
+void SPI_Stop_Transmission(volatile uint8_t *port, uint8_t pinNumber);
+
+#endif