BME280_SensorAPI/examples/linux_userspace.c

/*
	Linux userspace test code, simple and mose code directy from the doco.
	compile like this: gcc linux_userspace.c ../bme280.c -I ../ -o bme280
	tested: Raspberry Pi.
	Use like: ./bme280 /dev/i2c-0
*/

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <fcntl.h>
#include "bme280.h"

int fd;

int8_t user_i2c_read(uint8_t id, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
	if (write(fd, &reg_addr, sizeof(reg_addr)) < sizeof(reg_addr))
		return BME280_E_COMM_FAIL;
	if (read(fd, data, len) < len)
		return BME280_E_COMM_FAIL;
	return BME280_OK;
}

void user_delay_ms(uint32_t period)
{
	usleep(period * 1000);
}

int8_t user_i2c_write(uint8_t id, uint8_t reg_addr, uint8_t *data, uint16_t len)
{
	int8_t *buf;
	buf = malloc(len + 1);
	buf[0] = reg_addr;
	memcpy(buf + 1, data, len);
	if (write(fd, buf, len + 1) < len)
		return BME280_E_COMM_FAIL;
	free(buf);
	return BME280_OK;
}

void print_sensor_data(struct bme280_data *comp_data)
{
	float temp, press, hum;
#ifdef BME280_FLOAT_ENABLE
	temp = comp_data->temperature;
	press = 0.01 * comp_data->pressure;
	hum = comp_data->humidity;
#else
#ifdef BME280_64BIT_ENABLE
	temp = 0.01f * comp_data->temperature;
	press = 0.0001f * comp_data->pressure;
	hum = 1.0f / 1024.0f * comp_data->humidity;
#else
	temp = 0.01f * comp_data->temperature;
	press = 0.01f * comp_data->pressure;
	hum = 1.0f / 1024.0f * comp_data->humidity;
#endif
#endif
	printf("%0.2lf deg C, %0.2lf hPa, %0.2lf%%\n", temp, press, hum);
}

int8_t stream_sensor_data_forced_mode(struct bme280_dev *dev)
{
	int8_t rslt;
	uint8_t settings_sel;
	struct bme280_data comp_data;

	/* Recommended mode of operation: Indoor navigation */
	dev->settings.osr_h = BME280_OVERSAMPLING_1X;
	dev->settings.osr_p = BME280_OVERSAMPLING_16X;
	dev->settings.osr_t = BME280_OVERSAMPLING_2X;
	dev->settings.filter = BME280_FILTER_COEFF_16;

	settings_sel = BME280_OSR_PRESS_SEL | BME280_OSR_TEMP_SEL | BME280_OSR_HUM_SEL | BME280_FILTER_SEL;

	rslt = bme280_set_sensor_settings(settings_sel, dev);
	if (rslt != BME280_OK)
	{
		fprintf(stderr, "Failed to set sensor settings (code %+d).", rslt);
		return rslt;
	}

	printf("Temperature, Pressure, Humidity\n");
	/* Continuously stream sensor data */
	while (1)
	{
		rslt = bme280_set_sensor_mode(BME280_FORCED_MODE, dev);
		if (rslt != BME280_OK)
		{
			fprintf(stderr, "Failed to set sensor mode (code %+d).", rslt);
			break;
		}
		/* Wait for the measurement to complete and print data @25Hz */
		dev->delay_ms(40);
		rslt = bme280_get_sensor_data(BME280_ALL, &comp_data, dev);
		if (rslt != BME280_OK)
		{
			fprintf(stderr, "Failed to get sensor data (code %+d).", rslt);
			break;
		}
		print_sensor_data(&comp_data);
	}
	return rslt;
}

int main(int argc, char* argv[])
{
	struct bme280_dev dev;
	int8_t rslt = BME280_OK;

	if (argc < 2)
	{
		fprintf(stderr, "Missing argument for i2c bus.\n");
		exit(1);
	}
	
	// make sure to select BME280_I2C_ADDR_PRIM
	// or BME280_I2C_ADDR_SEC as needed
	dev.dev_id =
#if 1
		BME280_I2C_ADDR_PRIM
#else
		BME280_I2C_ADDR_SEC
#endif
		;

	dev.intf = BME280_I2C_INTF;
	dev.read = user_i2c_read;
	dev.write = user_i2c_write;
	dev.delay_ms = user_delay_ms;

	if ((fd = open(argv[1], O_RDWR)) < 0)
	{
		fprintf(stderr, "Failed to open the i2c bus %s\n", argv[1]);
		exit(1);
	}
	if (ioctl(fd, I2C_SLAVE, dev.dev_id) < 0)
	{
		fprintf(stderr, "Failed to acquire bus access and/or talk to slave.\n");
		exit(1);
	}
	
	rslt = bme280_init(&dev);
	if (rslt != BME280_OK)
	{
		fprintf(stderr, "Failed to initialize the device (code %+d).\n", rslt);
		exit(1);
	}
	rslt = stream_sensor_data_forced_mode(&dev);
	if (rslt != BME280_OK)
	{
		fprintf(stderr, "Failed to stream sensor data (code %+d).\n", rslt);
		exit(1);
	}
	return 0;
}