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    BSEC + DevKit + BME688: Odd Gas Resistance Values

    S_Brohl
    Member

    Re: BSEC + DevKit + BME688: Odd Gas Resistance Values

    Hi Robin,

    Thank you for your reply! I actually am using the official code from the Bosch GitHub repository on my ESP8266 for the single sensor kit, and for my 8 sensor devkits I am using the provided software for those.

    I'm just wondering if there is any insight from BST on what this issue could be that I'm observing.

    Single Sensor Adafruit Board:

    TimeTempPressureHumidityResistance0Resistance1Resistance2Resistance3Resistance4Resistance5Resistance6Resistance7Resistance8Resistance9
    1.65E+0928.4499475.0241.8638550588230890.6254473.2213611518164081656623213555.8454102603951.6698499.3
    1.65E+0928.8199473.2537.441.02E+08576414.3594484.8670788253682834595793480977673684.2769490.9829821.7
    1.65E+0928.999472.4436.961.02E+08680398.7694237.3841932267202635675096556219.4753356.6830831.6886964.1
    1.65E+0928.9599470.38371.02E+08716835.8730645.8906194771702416087312581818.2785426.6866694.9906395.3
    1.65E+0928.9799470.1136.441.02E+08741760.3760490.2953667175992586431404602884.9807252.7885813.1943996.3
    1.65E+092999470.336.321.02E+08758378.1782725982843478448656642611627835.7832858.9909413.9961954
    1.65E+0929.0299471.7136.421.02E+08777820801565.61019539580828816846636639600.3850498.3932392.4969467.4
    1.65E+0929.0199469.936.451.02E+08791344.7825307.31047905384128377081911653061.3865595.9949246.8996351.3
    1.65E+0929.0299470.236.441.02E+08803925.4828814.31071550083998977142110651814.1869454.4944649.4990568.3
    1.65E+0929.0199468.2636.191.02E+08813990.4831337.51070499885780107275311658732.7879536.2961276.71015621
    1.65E+0929.0199469.4836.661.02E+08820348.5840032.81099597387079467398510676354883520.39619541018652
    1.65E+0929.0199470.636.651.02E+08831337.5852090.71095187287920587433757679045.1882378.3963311.41008122
    1.65E+0929.0199468.3837.341.02E+08814476.1837456.61067361685045427114199661285.1877839.7953889.11007378
    1.65E+0928.9999470.9436.811.02E+08818872.4841586.21094090287638417515597667753.5881239.3970846.21014866
    1.65E+0928.9999467.9536.811.02E+08825307.3849968.91107401188347267464237672357.2893932.8972921.61026309
    1.65E+0928.9999466.936.741.02E+08839516.3860142.81122191889873837572915686557.2903994.7983433.41026309

     

    8 Sensor DevKit - Brand New - Sensor 1
    Resistances in log10 format*

    TimeTempPRHR0R1R2R3R4R5R6R7R8R9
    1.65E+0927.65259994.662243.399355.5476033.7547193.7547193.8136263.883043.9534563.7547194.0995484.382774.540066
    1.65E+0929.27546994.641836.238895.9411874.3237354.4016035.107214.9739114.9064964.3048474.637834.7566714.822441
    1.65E+0930.34981994.692834.216346.3731864.5555164.6247655.4098725.2158125.1261854.4954874.8289144.8987694.937977
    1.65E+0931.29777994.729732.470656.5465944.6522134.7312725.5257155.3405185.2054794.5707784.9102054.9755915.008566
    1.65E+0932.14968994.698431.370256.6497544.7109234.7814895.6013825.3657635.2429964.6129164.9643515.0276675.054516
    1.65E+0932.99401994.722729.632516.7188764.7418164.8120835.638775.4030595.2719954.6360655.0026385.0556725.078842
    1.65E+0933.79791994.735328.59886.7784164.7654794.8389835.673645.4268745.3018794.6517565.0190745.0806775.103642
    1.65E+0934.34395994.74127.410946.8362954.7936594.8598515.6996075.4567815.3336064.680135.0450985.0985035.120774
    1.65E+0935.00123994.712226.828786.8662124.8003564.8661625.7102485.4597055.3311454.68385.0536515.1078625.128915
    1.65E+0935.49925994.70625.726056.8709134.8074854.8725665.719825.4693455.3394054.6889925.0612035.1150985.136863
    1.65E+0936.10093994.773625.266766.8945854.815734.8809975.7309755.4780555.3495294.6944985.068595.1224585.141421
    1.65E+0936.48013994.759624.745656.9437414.8251554.886845.740325.4932365.3687274.7018645.0761055.1268665.140013

     

    8 Sensor DevKit - Old/Current kit - Sensor 1
    Resistances in log10 format*

    TimeTempPRHR0R1R2R3R4R5R6R7R8R9
    1.65E+0927.49731994.447644.394495.3992143.884913.9527254.5002914.51574.5323693.9763624.5640114.8915725.074893
    1.65E+0929.02353994.432136.599936.8871635.0026385.028215.8577065.8145395.7829284.9809165.1698175.2878315.360479
    1.65E+0929.90529994.433434.274327.3847955.2715195.2932966.2070146.1474246.1049095.2158125.3622335.4330385.479204
    1.65E+0930.77458994.470332.798147.5795655.3897485.3985776.349796.2900376.2422175.3249175.44675.5061015.541805
    1.65E+0931.56893994.482731.598027.7147335.4637575.4753866.4533956.3865346.3337215.394145.4968165.5494025.591088
    1.65E+0932.22091994.471931.040427.8450885.503665.5139246.5314636.4418056.3838315.4333835.5373975.5910885.618483
    1.65E+0932.89288994.450230.352537.8419685.5261435.5360846.5545046.4690336.4161845.4560535.5566765.6150615.644344
    1.65E+0933.61231994.486128.575677.8901375.5571355.576696.5966866.5171036.4616045.4818985.5933275.6390475.667384
    1.65E+0934.11192994.465327.639957.9653755.5822465.5938266.6252536.5516626.4897355.502045.609335.6519845.677559
    1.65E+0934.65649994.491526.647187.9456375.5933275.6036756.6402736.5663536.5152765.5130945.6198065.6641435.68922
    1.65E+0935.22356994.477725.758037.9704525.6075235.6192776.662366.5833826.5266245.5261435.6283735.6763495.702163
    1.65E+0935.62075994.46625.175937.9817415.6090725.6190126.662366.5889026.5355385.5240115.638775.6836575.709922
    1.65E+0935.98298994.460824.560517.9992455.6270235.638776.6871776.6091156.5468745.5413625.6463125.6889095.710575
    1.65E+0936.45762994.457223.960728.0097915.6319025.641276.6898946.6117096.5494025.5449175.6480065.6942255.71749
    1.65E+0936.80986994.455623.480948.01035.6310855.6426656.693026.6169446.5525135.5512095.6548485.7021635.730975
    1.65E+0937.05718994.416123.254658.01035.6382175.6531286.7013366.6276086.567825.5553035.6559995.707325.728585
    1.65E+0937.4269994.451522.899478.01035.6421065.6537016.706166.6255886.5675265.564545.6638495.7079695.73545
    1.65E+0937.74416994.436522.620338.01035.6465945.6539876.7089996.6259246.5672335.555765.6603435.7044115.728926
    1.65E+0938.03395994.496722.545938.01035.6482895.6606346.7041436.6279456.564895.555765.6562885.7002445.728585
    1.65E+0938.31625994.497822.259138.01035.6426655.6494236.6977526.6235786.5599555.5539345.6548485.7053795.734758
    1.65E+0938.61852994.465821.768068.01035.6474415.65866.7085926.6309946.5701785.5589745.6641435.7099225.733035
    1.65E+0938.76342994.456221.293548.01035.6516995.6603436.7118566.6323576.5704745.5636075.6635565.7079695.736489
    1.65E+0939.01324994.457821.116248.01035.6508445.6609256.7143216.6350946.5743365.5612855.6650245.7118845.738923
    1.65E+0939.27555994.453220.834838.01035.6525565.6600526.7130876.6299766.5695885.5612855.6664985.7076445.736489
    1.65E+0939.38547994.404921.036678.01035.646035.659186.7110386.6282836.5654755.5589745.66185.7060255.732347

     

    1.02E+08 is equal to 8.0103 in Log10 format. So on both sensors I am seeing these same values. I see the same values with the new kit too, but not as observably prevalent as I do between these two.

    I'm begininning to think these sensors have gone bad now that I have this new kit which is not showing this same behavior.  Any thoughts from BST on this?

     

    BSTRobin
    Community Moderator

    Re: BSEC + DevKit + BME688: Odd Gas Resistance Values

    Hi S_Brohl,

    We see the first test using heater_301, the second test using other profiles?
    In the second test, did the same value appear in 'R0 or R1' of Brand New? We didn't see it in the table from yours

    We need more information about comparative verification. Such as same heater profiles, different sensors and different boards or different heater profiles and same boards, etc.
    And what the above mentioned, Did it work well before? when and what cause it.
    After that, we can judge if there is something wrong with the sensors.

    BSTRobin
    Community Moderator

    Re: BSEC + DevKit + BME688: Odd Gas Resistance Values

    Hi S_Brohl,

    Could you help give further feedback? Thanks.

    S_Brohl
    Member

    Re: BSEC + DevKit + BME688: Odd Gas Resistance Values

    Hi Robin,

    I reached out to a contact within BST (Florian) and he arranged some engineers (Mary and Muhammad) to take a look into this anomaly with me.

    Based on their observations they believe this saturation may be caused by a number of reasons such as direct contamination, topics like sensor aging, heater profile settings, individual sensor history, specimen composition and concentration.

    However, these sensors/devkits were not that old (maybe 3-4 months old), and I was using the default profile. But they assured me this was something they have seen before and it may also just be the calibration of the sensor and it's sensitivity to something in the background air composition.

    I performed a few additional tests after that meeting to determine if this may have been saturation due to something in the background air composition. So I exposed the sensors to some smoke from incense, as well as coffee, and I still saw these saturated values.

    At that point I decided to replace the devkits in my setup with new ones as well as a new single sensor. It appears the saturated values still do appear occassionally, but not as much as with what I was seeing in the data I provided above.

    I suspect Muhammad may be right that with longer burn-in of the sensor it may be that it is more sensitive to something in the air composition of the environment I am testing in. Although, I also suspect that the substances I am testing with may also be causing this.

    I'll continue to observe this behavior and if it gets really bad as before I will follow-up here on the forum in case it might help others. For the time being we are allowing these saturated values to coexist in our datasets, but we will likely be pruning the data in areas where it is constantly appearing.

    BSTRobin
    Community Moderator

    Re: BSEC + DevKit + BME688: Odd Gas Resistance Values

    Hi S_Brohl,

    Thank for your feedback.

    You can continue to observe this behavior and give further back after test.

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