How to convert the gas resistance of bme680 sensor to IAQ in thingy53

[Sachin Rawat]

Hi 
I am working on thingy53, Using Hello world application    NCS- 1.9.1

So I have enable the bme680 sensor of thingy53

I received the values for temp, pressure, humidity, gas resistance. ------How to change this gas resistance to IAQ value in thingy53-----  

This is my main.c 

/*
 * Copyright (c) 2012-2014 Wind River Systems, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr.h>
#include <drivers/sensor.h>

void main(void)
{
	
	const struct device *bme = DEVICE_DT_GET_ONE(bosch_bme680);
	struct sensor_value temp, press, humidity, gas_res;


	if (!device_is_ready(bme)) {
		printk("sensor: device not ready.\n");
		return;
	}
	printk("Device %p name is %s\n", bme, bme->name);

	while (1) {
		k_sleep(K_MSEC(3000));

		sensor_sample_fetch(bme);
		sensor_channel_get(bme, SENSOR_CHAN_AMBIENT_TEMP, &temp);
		sensor_channel_get(bme, SENSOR_CHAN_PRESS, &press);
		sensor_channel_get(bme, SENSOR_CHAN_HUMIDITY, &humidity);
		sensor_channel_get(bme, SENSOR_CHAN_GAS_RES, &gas_res);

		printk("T: %d.%06d | P: %d.%06d | H: %d.%06d | G: %d.%06d\n",
				temp.val1, temp.val2, press.val1, press.val2,
				humidity.val1, humidity.val2, gas_res.val1,
				gas_res.val2);
	}
}

And this is the output on RTT monitor

I have gone through many tickets but didn't find a solution.

Please help

[Sachin Rawat]

Hi

Yes I have already looked at it. and even I have already asked about this above 

Unknown said:

Edited:- I read in the docs bsec_bme_settings_t::next_call field is used to determine the frequency between measurements.   Please goto line 71 in above file,you will see I have only added run_gas[1], should I need to add more, If yes then what to add and what to write in the respective fields 

P.S- I only need IAQ 

Could you help me to know how to do that--->

Vidar Berg said:

t says that the sensor must be sampled periodically at the interval specified by the bsec_sensor_control() function.

I have made changes and the next_call is updating in every call. But still, it is stuck to only one value of IAQ.

[Vidar Berg]

Sorry, I missed your edit. You can probably use a timer instance (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.2.0/zephyr/kernel/services/timing/timers.html) to trigger the sensor measurements at the required interval.  

sachinrawat said:

I have made changes and the next_call is updating in every call. But still, it is stuck to only one value of IAQ.

Not sure if you did this already, but you have to repeat the measurement too. 

[Sachin Rawat]

Hi sorry for the late reply,

If you look into the bme680.c file which I have shared above, I am repeating the code by calling the function env_sensor(); again and again in main.c, and even I have checked the next call is also updating whenever I am calling bsec_do_steps();

I have seen in the timers doc that we can use the k_sleep, I am already using that.

 

[Vidar Berg]

OK, it was not clear that env_sensor() was called in a loop. But it does not look like you are supposed to repeat the initialization on every iteration. You can have a look at the bsec2.cpp: Bsec2::run() implementation in the library example for comparison. 

Does bsec_sensor_control() return a valid timestamp?

[Sachin Rawat]

Vidar Berg said:

it was not clear that env_sensor() was called in a loop

I am calling this function in main.c inside for(;;) loop along with other sensors.

Vidar Berg said:

Does bsec_sensor_control() return a valid timestamp?

        date_time_now(&unix_timestamp);

        unix_timestamp_ns = unix_timestamp*1000000;

        bsec_bme_settings_t bsecConf; 

        bsec_sensor_control(unix_timestamp_ns,&bsecConf);

This is how I am passing the timestamp in ns to this function and I have seen it unix_timestamp_ns is passing the value perfectly.

The value of the IAQ is not changing, please help.