bsec_bme680.c

/* Copyright (C) 2017 alexh.name */
/* I2C code by twartzek 2017 */

/*
 * Read the BME680 sensor with the BSEC library by running an endless loop in
 * the bsec_iot_loop() function under Linux.
 *
 */

/* header files */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <linux/i2c-dev.h>
#include "bsec_datatypes.h"
#include "bsec_integration.h"
#include "bme680.h"

/* definitions */

#define DESTZONE "TZ=Europe/Berlin"
#define temp_offset (5.0f)
#define sample_rate_mode (BSEC_SAMPLE_RATE_LP)

int g_i2cFid; // I2C Linux device handle
int i2c_address = BME680_I2C_ADDR_PRIMARY;
char *filename_state = "bsec_iaq.state";
char *filename_config = "bsec_iaq.config";

/* functions */

// 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);
  }
}

/*
 * Write operation in either I2C or SPI
 *
 * param[in]        dev_addr        I2C or SPI device address
 * param[in]        reg_addr        register address
 * param[in]        reg_data_ptr    pointer to the data to be written
 * param[in]        data_len        number of bytes to be written
 *
 * return          result of the bus communication function
 */
int8_t bus_write(uint8_t dev_addr, uint8_t reg_addr, uint8_t *reg_data_ptr,
                 uint16_t data_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<data_len+1; i++)
    reg[i] = reg_data_ptr[i-1];

  if (write(g_i2cFid, reg, data_len+1) != data_len+1) {
    perror("user_i2c_write");
    rslt = 1;
    exit(1);
  }

  return rslt;
}

/*
 * Read operation in either I2C or SPI
 *
 * param[in]        dev_addr        I2C or SPI device address
 * param[in]        reg_addr        register address
 * param[out]       reg_data_ptr    pointer to the memory to be used to store
 *                                  the read data
 * param[in]        data_len        number of bytes to be read
 *
 * return          result of the bus communication function
 */
int8_t bus_read(uint8_t dev_addr, uint8_t reg_addr, uint8_t *reg_data_ptr,
                uint16_t data_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_ptr, data_len) != data_len) {
    perror("user_i2c_read_data");
    rslt = 1;
  }

  return rslt;
}

/*
 * System specific implementation of sleep function
 *
 * param[in]       t_ms    time in milliseconds
 *
 * return          none
 */
void _sleep(uint32_t t_ms)
{
  struct timespec ts;
  ts.tv_sec = 0;
  /* mod because nsec must be in the range 0 to 999999999 */
  ts.tv_nsec = (t_ms % 1000) * 1000000L;
  nanosleep(&ts, NULL);
}

/*
 * Capture the system time in microseconds
 *
 * return          system_current_time    system timestamp in microseconds
 */
int64_t get_timestamp_us()
{
  struct timespec spec;
  //clock_gettime(CLOCK_REALTIME, &spec);
  /* MONOTONIC in favor of REALTIME to avoid interference by time sync. */
  clock_gettime(CLOCK_MONOTONIC, &spec);

  int64_t system_current_time_ns = (int64_t)(spec.tv_sec) * (int64_t)1000000000
                                   + (int64_t)(spec.tv_nsec);
  int64_t system_current_time_us = system_current_time_ns / 1000;

  return system_current_time_us;
}

/*
 * Handling of the ready outputs
 *
 * param[in]       timestamp       time in microseconds
 * param[in]       iaq             IAQ signal
 * param[in]       iaq_accuracy    accuracy of IAQ signal
 * param[in]       temperature     temperature signal
 * param[in]       humidity        humidity signal
 * param[in]       pressure        pressure signal
 * param[in]       raw_temperature raw temperature signal
 * param[in]       raw_humidity    raw humidity signal
 * param[in]       gas             raw gas sensor signal
 * param[in]       bsec_status     value returned by the bsec_do_steps() call
 *
 * return          none
 */
void output_ready(int64_t timestamp, float iaq, uint8_t iaq_accuracy,
                  float temperature, float humidity, float pressure,
                  float raw_temperature, float raw_humidity, float gas,
                  bsec_library_return_t bsec_status)
{
  //int64_t timestamp_s = timestamp / 1000000000;
  ////int64_t timestamp_ms = timestamp / 1000;

  //time_t t = timestamp_s;
  /*
   * timestamp for localtime only makes sense if get_timestamp_us() uses
   * CLOCK_REALTIME
   */
  time_t t = time(NULL);
  struct tm tm = *localtime(&t);

  printf("{\"IAQ_Accuracy\": \"%d\",\"IAQ\":\"%.2f\"", iaq_accuracy, iaq);
  printf(",\"Temperature\": \"%.2f\",\"Humidity\": \"%.2f\",\"Pressure\": \"%.2f\"", temperature, humidity,pressure / 100);
  printf(",\"Gas\": \"%.0f\"", gas);
  printf(",\"Status\": \"%d\"}", bsec_status);
  //printf(",%" PRId64, timestamp);
  //printf(",%" PRId64, timestamp_ms);
  printf("\r\n");
  fflush(stdout);
}

/*
 * Load binary file from non-volatile memory into buffer
 *
 * param[in,out]   state_buffer    buffer to hold the loaded data
 * param[in]       n_buffer        size of the allocated buffer
 * param[in]       filename        name of the file on the NVM
 * param[in]       offset          offset in bytes from where to start copying
 *                                  to buffer
 * return          number of bytes copied to buffer or zero on failure
 */
uint32_t binary_load(uint8_t *b_buffer, uint32_t n_buffer, char *filename,
                     uint32_t offset)
{
  int32_t copied_bytes = 0;
  int8_t rslt = 0;

  struct stat fileinfo;
  rslt = stat(filename, &fileinfo);
  if (rslt != 0) {
    perror("stat'ing binary file");
    return 0;
  }

  uint32_t filesize = fileinfo.st_size - offset;

  if (filesize > n_buffer) {
    fprintf(stderr,"%s: %d > %d\n", "binary data bigger than buffer", filesize,
            n_buffer);
    return 0;
  } else {
    FILE *file_ptr;
    file_ptr = fopen(filename,"rb");
    if (!file_ptr) {
      perror("fopen");
      return 0;
    }
    fseek(file_ptr,offset,SEEK_SET);
    copied_bytes = fread(b_buffer,sizeof(char),filesize,file_ptr);
    if (copied_bytes == 0) {
      fprintf(stderr,"%s\n","binary_load");
    }
    fclose(file_ptr);
    return copied_bytes;
  }
}

/*
 * Load previous library state from non-volatile memory
 *
 * param[in,out]   state_buffer    buffer to hold the loaded state string
 * param[in]       n_buffer        size of the allocated state buffer
 *
 * return          number of bytes copied to state_buffer or zero on failure
 */
uint32_t state_load(uint8_t *state_buffer, uint32_t n_buffer)
{
  int32_t rslt = 0;
  rslt = binary_load(state_buffer, n_buffer, filename_state, 0);
  return rslt;
}

/*
 * Save library state to non-volatile memory
 *
 * param[in]       state_buffer    buffer holding the state to be stored
 * param[in]       length          length of the state string to be stored
 *
 * return          none
 */
void state_save(const uint8_t *state_buffer, uint32_t length)
{
  FILE *state_w_ptr;
  state_w_ptr = fopen(filename_state,"wb");
  fwrite(state_buffer,length,1,state_w_ptr);
  fclose(state_w_ptr);
}

/*
 * Load library config from non-volatile memory
 *
 * param[in,out]   config_buffer    buffer to hold the loaded state string
 * param[in]       n_buffer         size of the allocated state buffer
 *
 * return          number of bytes copied to config_buffer or zero on failure
 */
uint32_t config_load(uint8_t *config_buffer, uint32_t n_buffer)
{
  int32_t rslt = 0;
  /*
   * Provided config file is 4 bytes larger than buffer.
   * Apparently skipping the first 4 bytes works fine.
   *
   */
  rslt = binary_load(config_buffer, n_buffer, filename_config, 4);
  return rslt;
}

/* main */

/*
 * Main function which configures BSEC library and then reads and processes
 * the data from sensor based on timer ticks
 *
 * return      result of the processing
 */
int main()
{
  putenv(DESTZONE); // Switch to destination time zone

  i2cOpen();
  i2cSetAddress(i2c_address);

  return_values_init ret;

  ret = bsec_iot_init(sample_rate_mode, temp_offset, bus_write, bus_read,
                      _sleep, state_load, config_load);
  if (ret.bme680_status) {
    /* Could not intialize BME680 */
    return (int)ret.bme680_status;
  } else if (ret.bsec_status) {
    /* Could not intialize BSEC library */
    return (int)ret.bsec_status;
  }

  /* Call to endless loop function which reads and processes data based on
   * sensor settings.
   * State is saved every 10.000 samples, which means every 10.000 * 3 secs
   * = 500 minutes (depending on the config).
   *
   */
  bsec_iot_loop(_sleep, get_timestamp_us, output_ready, state_save, 10000);

  i2cClose();
  return 0;
}