smart-home/weather-sensor/firmware/bme280_interface.c

#include <avr/io.h>
#include <util/delay.h>

#include "bme280.h"
#include "bme280_interface.h"

/* for debugging */
#include "uart_debug.h"
#include <stdint.h>
#include <stdio.h>
#include <string.h>


void user_delay_ms(uint32_t period);
int8_t user_spi_read(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len);
int8_t user_spi_write(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len);


struct bme280_dev deviceStructure;
uint32_t req_delay;


int8_t Initialize_BME280(void)
{
	int8_t rslt = BME280_OK;
	uint8_t settings_sel;
	char debugString[20] = "";


	/* Setup the SPI interface */
	BME_CSN_DDR |= (1 << BME_CSN_PIN);
	BME_CSN_PORT |= (1 << BME_CSN_PIN);


	/* Sensor_0 interface over SPI with native chip select line */
	deviceStructure.dev_id = 0;
	deviceStructure.intf = BME280_SPI_INTF;
	deviceStructure.read = user_spi_read;
	deviceStructure.write = user_spi_write;
	deviceStructure.delay_ms = user_delay_ms;

	rslt = bme280_init(&deviceStructure);

	/* Settings for mode of operation: weather monitorint */
	deviceStructure.settings.osr_h = BME280_OVERSAMPLING_1X;
	deviceStructure.settings.osr_p = BME280_OVERSAMPLING_1X;
	deviceStructure.settings.osr_t = BME280_OVERSAMPLING_1X;
	deviceStructure.settings.filter = BME280_FILTER_COEFF_OFF;

	settings_sel = BME280_OSR_PRESS_SEL | BME280_OSR_TEMP_SEL | BME280_OSR_HUM_SEL | BME280_FILTER_SEL;

	rslt = bme280_set_sensor_settings(settings_sel, &deviceStructure);

	/* calculate minimum delay required between consecutive measurments */
	req_delay = bme280_cal_meas_delay(&deviceStructure.settings);

	sprintf(debugString, "req delay: %ld\r\n", req_delay);
	Print_Debug_String(debugString);

	return rslt;
}

/* Get one measurement in forced mode */
void BME280_Get_Measurement(void)
{
	int8_t rslt = BME280_OK;
	struct bme280_data comp_data;
	char debugString[30] = "";

	rslt = bme280_set_sensor_mode(BME280_FORCED_MODE, &deviceStructure);
	/* Wait for the measurement to complete and print data @25Hz */
	deviceStructure.delay_ms(req_delay);
	rslt = bme280_get_sensor_data(BME280_ALL, &comp_data, &deviceStructure);

	sprintf(debugString, "rslt: %d\r\n", rslt);
	Print_Debug_String(debugString);
	sprintf(debugString, "temp: %ld\r\n", comp_data.temperature);
	Print_Debug_String(debugString);
	sprintf(debugString, "hum: %ld\r\n", comp_data.humidity);
	Print_Debug_String(debugString);
	sprintf(debugString, "pres: %ld\r\n", comp_data.pressure);
	Print_Debug_String(debugString);
}

/* Implementation of the interface function needed by the BME280 library */
void user_delay_ms(uint32_t period)
{
	while (period--)
	{
		_delay_ms(1);
	}
}

int8_t user_spi_read(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
{
	int8_t rslt = 0; /* Return 0 for Success, non-zero for failure */

	/* 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

	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;
	}
	BME_CSN_PORT |= (1<<BME_CSN_PIN); // Stop the transmission

	return rslt;
}

int8_t user_spi_write(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
{
	int8_t rslt = 0; /* Return 0 for Success, non-zero for failure */

	/* unused parameters */
	(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

	for (uint16_t i = 0; i < len; i ++)
	{
		SPDR = reg_data[i]; /* value doesn't matter */
		while(!(SPSR & (1<<SPIF))); // Wait for transmission complete
	}
	BME_CSN_PORT |= (1<<BME_CSN_PIN); // Stop the transmission

	return rslt;
}