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bme680_main.c
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bme680_main.c
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/******************************
* Copyright (C) 2017 by Tobias Wartzek
* @file bme680_main.c
* @date 07.10.2017
* @version 1.0
* @brief Interface to BME680 from Raspberry Pi
*
*
* Read out temperature, pressure, humidity and gas sensor ohmic values
* via I²C and Raspberry Pi.
*
* History
* Version Date Detail
* 1.0 07.10.2017 Initial creation
*
******************************/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <linux/i2c-dev.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "bme680.h"
#define DESTZONE "TZ=Europe/Stockholm" // Our destination time zone
// I2C Linux device handle
int g_i2cFid;
// open the Linux device
void i2cOpen()
{
g_i2cFid = open("/dev/i2c-1", O_RDWR);
if (g_i2cFid < 0) {
perror("i2cOpen");
exit(1);
}
}
// close the Linux device
void i2cClose()
{
close(g_i2cFid);
}
// set the I2C slave address for all subsequent I2C device transfers
void i2cSetAddress(int address)
{
if (ioctl(g_i2cFid, I2C_SLAVE, address) < 0) {
perror("i2cSetAddress");
exit(1);
}
}
void user_delay_ms(uint32_t period)
{
sleep(period/1000);
}
int8_t user_i2c_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 */
uint8_t reg[1];
reg[0]=reg_addr;
if (write(g_i2cFid, reg, 1) != 1) {
perror("user_i2c_read_reg");
rslt = 1;
}
if (read(g_i2cFid, reg_data, len) != len) {
perror("user_i2c_read_data");
rslt = 1;
}
return rslt;
}
int8_t user_i2c_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 */
uint8_t reg[16];
reg[0]=reg_addr;
for (int i=1; i<len+1; i++)
reg[i] = reg_data[i-1];
if (write(g_i2cFid, reg, len+1) != len+1) {
perror("user_i2c_write");
rslt = 1;
exit(1);
}
return rslt;
}
void write2file(char *outputFile, struct tm tm, struct bme680_field_data data)
{
// Write measurement to output file if specified.
if(outputFile != NULL)
{
FILE *f = fopen(outputFile, "a");
if (f == NULL)
{
printf("Error opening file!\n");
//exit(1);
}
else
{
fprintf(f,"%d-%02d-%02d %02d:%02d:%02d ", tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
fprintf(f,"T: %.2f degC, P: %.2f hPa, H: %.2f %%rH", data.temperature / 100.0f,
data.pressure / 100.0f, data.humidity / 1000.0f );
fprintf(f,", G: %d Ohms", data.gas_resistance);
fprintf(f,"\r\n");
fclose(f);
}
}
}
int main(int argc, char *argv[] )
{
// create lock file first
FILE *f = fopen("~bme680i2c.lock", "w");
if (f == NULL)
{
printf("Error opening file!\n");
exit(1);
}
fprintf(f,"I2C locked by BME680 readout. \r\n");
fclose(f);
int delay = 3;
int nMeas = 3;
char *outputFile = NULL;
// Input argument parser
if( argc == 2 ) {
delay = strtol(argv[1], NULL, 10);
}
else if( argc == 3 ) {
delay = strtol(argv[1], NULL, 10);
nMeas = strtol(argv[2], NULL, 10);
}
else if( argc == 4 ) {
delay = strtol(argv[1], NULL, 10);
nMeas = strtol(argv[2], NULL, 10);
outputFile = argv[3];
}
else {
}
printf("**** BME680 start measurements ****\n");
time_t t = time(NULL);
putenv(DESTZONE); // Switch to destination time zone
// open Linux I2C device
i2cOpen();
// set address of the BME680
i2cSetAddress(BME680_I2C_ADDR_SECONDARY);
// init device
struct bme680_dev gas_sensor;
gas_sensor.dev_id = BME680_I2C_ADDR_SECONDARY;
gas_sensor.intf = BME680_I2C_INTF;
gas_sensor.read = user_i2c_read;
gas_sensor.write = user_i2c_write;
gas_sensor.delay_ms = user_delay_ms;
int8_t rslt = BME680_OK;
rslt = bme680_init(&gas_sensor);
uint8_t set_required_settings;
/* Set the temperature, pressure and humidity settings */
gas_sensor.tph_sett.os_hum = BME680_OS_2X;
gas_sensor.tph_sett.os_pres = BME680_OS_4X;
gas_sensor.tph_sett.os_temp = BME680_OS_8X;
gas_sensor.tph_sett.filter = BME680_FILTER_SIZE_3;
/* Set the remaining gas sensor settings and link the heating profile */
gas_sensor.gas_sett.run_gas = BME680_ENABLE_GAS_MEAS;
/* Create a ramp heat waveform in 3 steps */
gas_sensor.gas_sett.heatr_temp = 320; /* degree Celsius */
gas_sensor.gas_sett.heatr_dur = 150; /* milliseconds */
/* Select the power mode */
/* Must be set before writing the sensor configuration */
gas_sensor.power_mode = BME680_FORCED_MODE;
/* Set the required sensor settings needed */
set_required_settings = BME680_OST_SEL | BME680_OSP_SEL | BME680_OSH_SEL | BME680_FILTER_SEL
| BME680_GAS_SENSOR_SEL;
/* Set the desired sensor configuration */
rslt = bme680_set_sensor_settings(set_required_settings,&gas_sensor);
/* Set the power mode */
rslt = bme680_set_sensor_mode(&gas_sensor);
/* Get the total measurement duration so as to sleep or wait till the
* measurement is complete */
uint16_t meas_period;
bme680_get_profile_dur(&meas_period, &gas_sensor);
user_delay_ms(meas_period + delay*1000); /* Delay till the measurement is ready */
struct bme680_field_data data;
struct tm tm = *localtime(&t);
int i=0;
int backupCounter = 0;
while(i<nMeas && backupCounter < nMeas+5) {
// Get sensor data
rslt = bme680_get_sensor_data(&data, &gas_sensor);
// Avoid using measurements from an unstable heating setup
if(data.status & BME680_HEAT_STAB_MSK)
{
t = time(NULL);
tm = *localtime(&t);
printf("%d-%02d-%02d %02d:%02d:%02d ", tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
printf("T: %.2f degC, P: %.2f hPa, H: %.2f %%rH", data.temperature / 100.0f,
data.pressure / 100.0f, data.humidity / 1000.0f );
printf(", G: %d Ohms", data.gas_resistance);
printf("\r\n");
write2file(outputFile, tm, data);
i++;
}
// Trigger a meausurement
rslt = bme680_set_sensor_mode(&gas_sensor); /* Trigger a measurement */
// Wait for a measurement to complete
user_delay_ms(meas_period + delay*1000); /* Wait for the measurement to complete */
backupCounter++;
}
printf("**** Measurement finished ****\n");
// close Linux I2C device
i2cClose();
// delete lock file
remove("~bme680i2c.lock");
return 0;
}