BSEC + DevKit + BME688: Odd Gas Resistance Values

[S_Brohl]

Hello,

I'm noticing in my bmeraw files as well as my data output from a single BME688 sensor that while running different heater profiles with a duty cycle of 1:0  that I am seeing every so often the gas resistance value: 102400000.000000 on step index zero (and sometimes index 1). I don't believe this is normal as the previous values before it are much smaller. Is there any explaination for why this might be happening?

I have tried five different 8-sensor development kits and two seperate breakout boards with the BME688 and I still see this value output in my data when running with a duty cycle of 1:0. I am assuming this might be due to the profile transitioning so quickly from the last step index temperature back to the first, but I've also tested this using the default config that comes with the dev kits and see the same thing.

All of these sensors have undergone a 72hr burn-in period, but I am still wondering, do I need to allow the sensors to run 5 minutes before I can assume I am receiving genuine data?

Any insight into this anomaly would be greatly appreciated!

Also, here is some data so you can see what I am talking about:

Sensor 0:

Time since power-on	RTC Time in Seconds	Temp	Pressure	Rel. Humidity	Gas Resistance	HP Step Index	Scanning enabled	Heater Profile	Duty Cycle
116009	1.65E+09	29.26295	999.9167	24.46373	102400000	0	1	heater_301	duty_1
121804	1.65E+09	28.66775	999.906	24.44672	84074408	1	1	heater_301	duty_1
122084	1.65E+09	28.90533	999.8544	24.49614	4751740	2	1	heater_301	duty_1
123980	1.65E+09	29.55556	999.9169	24.54941	4136329.25	3	1	heater_301	duty_1
125940	1.65E+09	29.71061	999.9347	24.45399	3925251.5	4	1	heater_301	duty_1
127900	1.65E+09	29.84066	999.9174	24.44756	3477817.75	5	1	heater_301	duty_1
128180	1.65E+09	29.98571	999.8882	24.35675	383880.0313	6	1	heater_301	duty_1
130140	1.65E+09	30.48339	999.888	24.24382	520589.7188	7	1	heater_301	duty_1
132100	1.65E+09	30.63845	999.9015	24.10568	579841.4375	8	1	heater_301	duty_1
133932	1.65E+09	30.75849	999.9071	23.84773	614277.125	9	0	heater_301	duty_1
134382	1.65E+09	30.16327	999.9437	23.73542	102400000	0	1	heater_301	duty_1
140114	1.65E+09	29.51054	999.9561	23.76816	94534440	1	1	heater_301	duty_1
140394	1.65E+09	29.76313	999.9347	23.79697	5160315	2	1	heater_301	duty_1
142354	1.65E+09	30.40336	999.9016	23.88054	4527217.5	3	1	heater_301	duty_1
144314	1.65E+09	30.53841	999.8973	23.86371	4074608.25	4	1	heater_301	duty_1
146274	1.65E+09	30.65095	999.9001	23.67485	3757798.25	5	1	heater_301	duty_1
146554	1.65E+09	30.791	999.9001	23.73821	406268.5938	6	1	heater_301	duty_1
148374	1.65E+09	31.29619	999.9119	23.57239	548620.4375	7	1	heater_301	duty_1
150334	1.65E+09	31.48126	999.9209	23.38349	603417.8125	8	1	heater_301	duty_1
152306	1.65E+09	31.6013	999.9225	23.19007	642610.625	9	0	heater_301	duty_1
152750	1.65E+09	30.99358	999.8925	23.22111	102400000	0	1	heater_301	duty_1
158452	1.65E+09	30.28081	999.8987	23.10701	102400000	1	1	heater_301	duty_1
158732	1.65E+09	30.54591	999.8482	23.16282	5639931	2	1	heater_301	duty_1
160692	1.65E+09	31.21866	999.8992	23.25308	4760023	3	1	heater_301	duty_1
162652	1.65E+09	31.36121	999.9281	23.15172	4289005	4	1	heater_301	duty_1
164612	1.65E+09	31.44874	999.9263	23.03589	3902810.75	5	1	heater_301	duty_1
164892	1.65E+09	31.5888	999.8988	22.92911	419758.1563	6	1	heater_301	duty_1
166712	1.65E+09	32.07648	999.9006	22.92118	566841.9375	7	1	heater_301	duty_1
168672	1.65E+09	32.25155	999.8891	22.74788	629572.6875	8	1	heater_301	duty_1
170726	1.65E+09	32.3966	999.9071	22.66266	661926.3125	9	0	heater_301	duty_1
171028	1.65E+09	31.73385	999.9297	22.46285	102400000	0	1	heater_301	duty_1
176824	1.65E+09	31.04359	999.8773	22.51532	102400000	1	1	heater_301	duty_1
177106	1.65E+09	31.31369	999.9058	22.5552	5734686.5	2	1	heater_301	duty_1
179077	1.65E+09	31.97894	999.9767	22.62806	4870392.5	3	1	heater_301	duty_1
180910	1.65E+09	32.124	999.9371	22.56409	4367902	4	1	heater_301	duty_1
182870	1.65E+09	32.23154	999.9473	22.45517	3991230.25	5	1	heater_301	duty_1
183150	1.65E+09	32.37159	999.9283	22.44376	428451.875	6	1	heater_301	duty_1
185111	1.65E+09	32.86929	999.9265	22.35142	576901.4375	7	1	heater_301	duty_1
187106	1.65E+09	33.02935	999.9626	22.16148	641403.0625	8	1	heater_301	duty_1
189092	1.65E+09	33.14439	999.9391	21.9686	678370.3125	9	0	heater_301	duty_1
189546	1.65E+09	32.40911	999.9216	21.95513	102400000	0	1	heater_301	duty_1
195227	1.65E+09	31.80138	999.9281	21.9716	102400000	1	1	heater_301	duty_1
195368	1.65E+09	32.07148	999.9323	21.92154	5734686.5	2	1	heater_301	duty_1
197328	1.65E+09	32.72173	999.9356	22.0874	4879094.5	3	1	heater_301	duty_1
199300	1.65E+09	32.84678	999.9012	22.00623	4396029	4	1	heater_301	duty_1
201261	1.65E+09	32.95432	999.931	21.87639	4245659.5	5	1	heater_301	duty_1
201541	1.65E+09	33.09938	999.9231	21.87577	426844.5313	6	1	heater_301	duty_1
203563	1.65E+09	33.60708	999.9446	21.76272	578367.6875	7	1	heater_301	duty_1
205387	1.65E+09	33.76964	999.9698	21.67355	652437.0625	8	1	heater_301	duty_1
207372	1.65E+09	33.88219	999.9709	21.45971	690026.9375	9	0	heater_301	duty_1
207812	1.65E+09	33.25694	999.9443	21.34916	102400000	0	1	heater_301	duty_1
213453	1.65E+09	32.50665	999.9229	21.4565	102400000	1	1	heater_301	duty_1
213757	1.65E+09	32.77175	999.8948	21.40598	5914801.5	2	1	heater_301	duty_1
215717	1.65E+09	33.44952	999.9363	21.6043	5018070.5	3	1	heater_301	duty_1
217677	1.65E+09	33.56956	999.9498	21.49652	4542279	4	1	heater_301	duty_1
219640	1.65E+09	33.6621	999.9875	21.39219	4142604.25	5	1	heater_301	duty_1
219960	1.65E+09	33.80966	999.9814	21.4074	435559.3438	6	1	heater_301	duty_1
221781	1.65E+09	34.29736	999.9784	21.32441	590371.875	7	1	heater_301	duty_1
223744	1.65E+09	34.46743	999.9862	21.11467	660006.4375	8	1	heater_301	duty_1
225728	1.65E+09	34.59248	999.9598	20.94943	702091.1875	9	0	heater_301	duty_1
226154	1.65E+09	33.97222	999.983	20.84532	102400000	0	1	heater_301	duty_1
231801	1.65E+09	33.1744	999.906	20.96571	102400000	1	1	heater_301	duty_1
232081	1.65E+09	33.43201	999.9029	21.0142	6056931.5	2	1	heater_301	duty_1
234041	1.65E+09	34.12228	999.95	21.08634	5107232	3	1	heater_301	duty_1
236001	1.65E+09	34.26734	999.9576	21.01716	4611314.5	4	1	heater_301	duty_1
237903	1.65E+09	34.35738	999.9641	20.91805	4136329.25	5	1	heater_301	duty_1
238184	1.65E+09	34.50244	999.921	20.9014	437233.125	6	1	heater_301	duty_1
240144	1.65E+09	34.99014	999.9292	20.81813	600762.6875	7	1	heater_301	duty_1
242103	1.65E+09	35.1427	999.9446	20.63906	673684.1875	8	1	heater_301	duty_1
244088	1.65E+09	35.25275	999.9229	20.48881	709386.9375	9	0	heater_301	duty_1
244532	1.65E+09	34.61999	999.9406	20.38989	102400000	0	1	heater_301	duty_1
250151	1.65E+09	33.84967	999.9334	20.55437	102400000	1	1	heater_301	duty_1
250445	1.65E+09	34.11728	999.9347	20.58229	6114573.5	2	1	heater_301	duty_1
252433	1.65E+09	34.77505	999.9386	20.71984	5184810	3	1	heater_301	duty_1
254436	1.65E+09	34.9051	999.9671	20.59194	4588070.5	4	1	heater_301	duty_1
256257	1.65E+09	35.00264	999.9599	20.48818	4174267.5	5	1	heater_301	duty_1
256537	1.65E+09	35.1452	999.9069	20.49226	437513.3438	6	1	heater_301	duty_1
258496	1.65E+09	35.65041	999.9525	20.36266	604486.4375	7	1	heater_301	duty_1
260457	1.65E+09	35.79798	999.9559	20.22542	669718.75	8	1	heater_301	duty_1
262449	1.65E+09	35.90052	999.9582	20.05914	708650.5	9	0	heater_301	duty_1
262886	1.65E+09	35.27526	999.9644	19.97709	102400000	0	1	heater_301	duty_1
268544	1.65E+09	34.45492	999.9391	20.12302	102400000	1	1	heater_301	duty_1
268823	1.65E+09	34.71753	999.9226	20.13989	6121427	2	1	heater_301	duty_1
270810	1.65E+09	35.42782	999.9488	20.20665	5116802	3	1	heater_301	duty_1
272770	1.65E+09	35.54537	999.968	20.10953	4706693.5	4	1	heater_301	duty_1
274729	1.65E+09	35.6179	999.9858	19.96768	4152052.75	5	1	heater_301	duty_1
275010	1.65E+09	35.76296	999.9381	20.03456	437793.9375	6	1	heater_301	duty_1
276969	1.65E+09	36.25067	999.9799	19.90888	595521.9375	7	1	heater_301	duty_1
278790	1.65E+09	36.41824	999.9913	19.74168	667753.5	8	1	heater_301	duty_1
280775	1.65E+09	36.53079	999.982	19.57631	718344.4375	9	0	heater_301	duty_1
281202	1.65E+09	35.88802	999.9655	19.4731	102400000	0	1	heater_301	duty_1
286911	1.65E+09	35.05517	999.9478	19.65521	102400000	1	1	heater_301	duty_1
287190	1.65E+09	35.31527	999.8976	19.70814	6152459.5	2	1	heater_301	duty_1
289151	1.65E+09	36.01057	999.9725	19.76274	5112012.5	3	1	heater_301	duty_1
291111	1.65E+09	36.13062	999.968	19.68154	4580374.5	4	1	heater_301	duty_1
293072	1.65E+09	36.22316	999.9904	19.59339	4111417.75	5	1	heater_301	duty_1
293351	1.65E+09	36.36572	999.9728	19.59197	438637.8125	6	1	heater_301	duty_1
295311	1.65E+09	36.85343	999.9716	19.49745	589861.75	7	1	heater_301	duty_1
297271	1.65E+09	36.98349	999.9554	19.32804	670376.4375	8	1	heater_301	duty_1
299117	1.65E+09	37.09353	999.958	19.19403	715333.5625	9	0	heater_301	duty_1
299623	1.65E+09	36.45826	1000.01	19.09717	102400000	0	1	heater_301	duty_1
305223	1.65E+09	35.44783	999.9228	18.43421	102400000	1	1	heater_301	duty_1
305503	1.65E+09	35.71544	999.913	18.42436	6135180.5	2	1	heater_301	duty_1
307464	1.65E+09	36.37322	999.994	18.11216	5259711	3	1	heater_301	duty_1
309446	1.65E+09	36.47076	999.9824	17.71054	4670467.5	4	1	heater_301	duty_1
311413	1.65E+09	36.5483	1000.021	17.37048	4242361.5	5	1	heater_301	duty_1
311694	1.65E+09	36.68086	999.9979	17.33181	451101.3125	6	1	heater_301	duty_1
313665	1.65E+09	37.16607	999.9792	17.04103	627835.6875	7	1	heater_301	duty_1
315588	1.65E+09	37.27361	999.9926	16.84199	711605.3125	8	1	heater_301	duty_1
317574	1.65E+09	37.35365	1000.007	16.48828	759643.9375	9	0	heater_301	duty_1
318013	1.65E+09	36.69086	1000.027	16.30949	102400000	0	1	heater_301	duty_1
323650	1.65E+09	35.84049	999.9459	16.20797	102400000	1	1	heater_301	duty_1
323930	1.65E+09	36.12061	999.9647	16.23817	6757682	2	1	heater_301	duty_1
325916	1.65E+09	36.7784	999.9827	16.24799	5675095.5	3	1	heater_301	duty_1
327770	1.65E+09	36.87844	999.9496	16.13119	5145728.5	4	1	heater_301	duty_1
329730	1.65E+09	36.94597	999.9828	16.00764	4607424	5	1	heater_301	duty_1
330010	1.65E+09	37.08853	999.9702	16.06607	469401.7813	6	1	heater_301	duty_1
331944	1.65E+09	37.57124	999.9794	15.91363	646873	7	1	heater_301	duty_1
333904	1.65E+09	37.6988	999.9933	15.73728	736161.0625	8	1	heater_301	duty_1
335890	1.65E+09	37.78634	999.9817	15.57422	777820	9	0	heater_301	duty_1
336327	1.65E+09	37.14856	1000.011	15.48542	102400000	0	1	heater_301	duty_1
341946	1.65E+09	36.26318	999.9908	15.57136	102400000	1	1	heater_301	duty_1
342226	1.65E+09	36.54079	999.9926	15.45417	7000213.5	2	1	heater_301	duty_1
344210	1.65E+09	37.20608	999.9939	15.63031	5795543	3	1	heater_301	duty_1
346182	1.65E+09	37.31113	1000.012	15.53942	5204574.5	4	1	heater_301	duty_1
348182	1.65E+09	37.37366	1000.006	15.46156	4710753.5	5	1	heater_301	duty_1
348462	1.65E+09	37.51622	999.9717	15.33719	471346.375	6	1	heater_301	duty_1
350282	1.65E+09	37.97892	999.9919	15.35586	651192.375	7	1	heater_301	duty_1
352243	1.65E+09	38.10148	1000.005	15.22529	741760.25	8	1	heater_301	duty_1
354228	1.65E+09	38.19152	1000.017	15.10326	784975.0625	9	0	heater_301	duty_1
354683	1.65E+09	37.55124	1000.006	15.02543	102400000	0	1	heater_301	duty_1
360427	1.65E+09	36.66085	1000.008	15.12701	102400000	1	1	heater_301	duty_1
360706	1.65E+09	36.94347	999.9789	15.16144	7004703	2	1	heater_301	duty_1
362565	1.65E+09	37.59876	1000.027	15.24017	5870297.5	3	1	heater_301	duty_1
364538	1.65E+09	37.70631	1000.032	15.18492	5150581.5	4	1	heater_301	duty_1
366526	1.65E+09	37.77884	1000.048	15.11778	4282279	5	1	heater_301	duty_1
366805	1.65E+09	37.9239	1000.033	15.21624	428990.375	6	1	heater_301	duty_1
368766	1.65E+09	38.39161	1000.064	15.04251	463978.25	7	1	heater_301	duty_1
370725	1.65E+09	38.50916	1000.091	14.91179	445507.9375	8	1	heater_301	duty_1
372571	1.65E+09	38.5892	1000.1	14.78432	422878.375	9	0	heater_301	duty_1
373010	1.65E+09	37.94641	1000.082	14.69186	66483388	0	1	heater_301	duty_1
378779	1.65E+09	37.07352	1000.035	14.78982	46761328	1	1	heater_301	duty_1
378963	1.65E+09	37.32864	1000.013	14.80244	2718884.75	2	1	heater_301	duty_1
380935	1.65E+09	37.99143	1000.053	14.87576	1854652.5	3	1	heater_301	duty_1
382909	1.65E+09	38.09398	1000.062	14.79503	1472322.125	4	1	heater_301	duty_1
384898	1.65E+09	38.1465	1000.069	14.6513	1217598.125	5	1	heater_301	duty_1
385179	1.65E+09	38.29407	1000.06	14.69895	195121.9531	6	1	heater_301	duty_1
387139	1.65E+09	38.77929	1000.091	14.57652	263713.625	7	1	heater_301	duty_1
389098	1.65E+09	38.90434	1000.087	14.45144	271258.2813	8	1	heater_301	duty_1
390943	1.65E+09	38.97688	1000.086	14.28858	272557.9063	9	0	heater_301	duty_1

[ilcnet]

Hello dear BSTRobin

Yes of course you you can see from this link:
https://vimeo.com/726695453

If you see this video the Bme688 will be start at the first step with iaq 25 and co2 500 values and after about 5 minutes the value starts to work and going up down up down that's true from here but if you see video in continue after i spray ethanol the values start to go down immediately unfortunately.

Thanks

[BSTRobin]

Hi ilcnet,

We have viewed the video you provided. The following situations should be guaranteed.
1、Importance: Accuracy output is from 0~1 according to the video, the customer need to test after the accuracy is 3. Here is the values of accuracy mean:
0: the sensor is not yet stabilized or in a run-in status
1: calibration required
2: calibration on-going
3: calibration is done
2、All procedures should follow the intergration_guide
3、Reducing will decrease sensor resistance, on the contrary, oxidizing will increase sensor resistance. Make sure that there is no strongly oxidizing condition surrounding sensor when you doing additional behavior, otherwise, it may lead wrong read out of BME since it may output "clean" air.
And we test it by spraying ethanol, the result is IAQ will increase which is different from you described.

[ilcnet]

Hello dear BSTRobin

I adjusted the sensor to accuracy level 3 according to your instructions, and again the sensor readings decrease inversely when exposed to ethanol. Apart from this, I have three other sensors, they also have the same function, unfortunately.

I don't know one thing, when after 3 days the sensor shows an accuracy number of 3, is that enough? Does that mean the sensor was calibrated forever? It means that the values ​​are saved automatically? So why does the output terminal show zero accuracy after restarting, which means that when we used the sensor in the project, it should take 3 days to calibrate every time it is restarted? Unfortunately, my problem has not been solved.

The video in question was taken after 3 days of calibration and the accuracy number is 3, because the sensor has to be rebooted to upload the code, for this reason the accuracy number shows zero.

[BSTRobin]

Hi ilcnet,

Could you provide your video or record your print information in the code?

[BSTRobin]

Hi ilcnet,

Please also provide your whole project code for check, thanks.