I2C BME688 0x77 on Arduino MKR Zero: custom heater profile and gas resistant logging.

[DN_LiU]

Hi,

We have a project to study gas emission from cooking activity in a tropical country, to determine its affect on women health. We would like to try the gas scan function of the BME688s to find the VOCs "fingerprint" when people use different fuel materials (as cow dung, wood, kerosel, etc) and the cooking foods. For this purpose of trying to distinguish gases emission from cooking activities at different areas, after reading on this forum and some publications, I think about applying a heater profile and log as much data as posible. We have a 32 GB SD card. I use "bme68xLibrary.h"

// /* Heater temperature in degree Celsius */

uint16_t tempProf[22] = {400, 100, 400, 125, 400, 150, 400, 175, 400, 200, 400, 250, 400, 275, 400, 300,400, 325, 400, 350, 400, 375};

// /* Heating duration in millismillisseconds */

uint16_t durProf[22] = { 5000, 7000, 5000, 7000,5000, 7000, 5000, 7000, 5000,7000,5000,7000, 5000,7000,5000,7000,5000,7000,5000,7000, 5000,7000};

However, the MKR got frozen after run in the function bme.setHeaterProf(tempProf, durProf, 22);

Then I tried with the force mode, 

bme.setHeaterProf(temp, 5000); // Set the gas heater temperature and duration

bme.setOpMode(BME68X_FORCED_MODE);

It takes 4040 ms for bme.fetchData() == 1, and the bme.getData(data) only return a value of data.gas_resistance; the arduino code is in attachment. I wonder if there is a possibility to record all gas resistance values over the heater profile cycle.

Thanks in advance. I really appreciate for all suggestion and recommendation.

[BSTRobin]

Hi DN_LiU,

If you used 2400, which can not support SQUENTIAL MODE, but you can use it without BSEC, in the meanwhile, you can only get raw data.

[DN_LiU]

Hi Robin, I'm sorry for my confusion, what is "2400"?. For this pilot studying, we would like to have the raw gas resistance value over a temperature profile to see the VOCs "fingerprint" from cooking activities which we have never studied in before. Any suggestion and recommendation is very valuable for us. We built a sensor node which included many sensors to see if we can track most of the toxic gases that badly affect peoples' healthy.

I have play around with the BSEC2, but not sure how to use it on I2C communication with one or two BME688 at 0x76 and 0x77.

[BSTRobin · Accepted solution]

Hi DN_LiU,

2400 is latest BSEC library which can be downloaded from https://www.bosch-sensortec.com/software-tools/software/bme688-software. It contains an example code that demonstrates how to use BME688 and BSEC.

[nm_]

Hello

Does the BME688 support a 450 degree temperature? Say, if a heater profile were to be set between 350 and 450?

If not--does Bosch-Sensortec have any other sensors that do? I see in your response you recommend 200-400, and I have a use case that requires slightly hire temperatures

Thank you for your active moderation and answering, and for your time and attention