I have Adafruit ESP32-S2 Feather with BME280 Sensor that correctly records temperature and humidity. When I add a Adafruit PMSA003I Air quality sensor via the Stemma (I2C interface) the Bme280 gives me strange temperature and humidity readings. Almost like the values have swapped.
For example, before adding the PMSA003I the temperature data from the BME280 was showing temp at 25.12 Degrees and Humidity 33.85%. After adding the PMSA003I the BME280 temperature shows 34 Degrees and the Humidity around 24%
I was wondering if the PMSA003I was running the CPU at max and that was causing the strange readings? I tried removing the PMSA003 sensor and leave the PMSA003 library in the sketch to see if it was the hardware or software, initially this too does seem to effect the Temperature and Humidity readings, although it did come back down after a period of time, possibly as there is no longer a call from main loop to read the PM2.5 data.
BME280 and PMSA0031 help.
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- adafruit_support_mike
- Posts: 67485
- Joined: Thu Feb 11, 2010 2:51 pm
Re: BME280 and PMSA0031 help.
No.. I2C devices communicate at 100kbps, which is far slower than the ESP32-S2's 240MHz clock.
Post a photo showing your hardware and connections and we'll take a look. 800x600 images usually work best.
- Kayie
- Posts: 4
- Joined: Fri Feb 17, 2023 1:35 pm
Re: BME280 and PMSA0031 help.
Picture As requested
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- bme280-PMSA0031.jpg (132.36 KiB) Viewed 130 times
- adafruit_support_mike
- Posts: 67485
- Joined: Thu Feb 11, 2010 2:51 pm
Re: BME280 and PMSA0031 help.
Thank you. I don't see anything obviously wrong there.
As a sanity check, have you tested the temperature of the Feather by other means to see if its temperature is actually changing? Air quality monitors work by burning off contaminants with a heater element, which at least increases the amount of current that flows through the traces on the Feather. Extra current generates extra heat, so there's a nonzero chance the hardware is giving you good readings.
As a sanity check, have you tested the temperature of the Feather by other means to see if its temperature is actually changing? Air quality monitors work by burning off contaminants with a heater element, which at least increases the amount of current that flows through the traces on the Feather. Extra current generates extra heat, so there's a nonzero chance the hardware is giving you good readings.
- Kayie
- Posts: 4
- Joined: Fri Feb 17, 2023 1:35 pm
Re: BME280 and PMSA0031 help.
Hi,
Here are the temperature and humidity results for last 12 hours from two devices side by side. One with a PMSA003I sensor (First one) and one with no PMSA003I. There is large disparity between the two, with the second device displaying the correct results.
I will remove the PMSA003I from the first device but leave library reference in the sketch then run it for another 12 hours.
Here are the temperature and humidity results for last 12 hours from two devices side by side. One with a PMSA003I sensor (First one) and one with no PMSA003I. There is large disparity between the two, with the second device displaying the correct results.
I will remove the PMSA003I from the first device but leave library reference in the sketch then run it for another 12 hours.
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- SensorPm25.png (20.27 KiB) Viewed 118 times
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- SensorNopm25.png (19.81 KiB) Viewed 118 times
- Kayie
- Posts: 4
- Joined: Fri Feb 17, 2023 1:35 pm
Re: BME280 and PMSA0031 help.
Turns out its nothing to do with the PMSA0031. I'm getting the incorrect readings when the feather is connected via USB. When connected via battery the results return to normal. Check out the attached picture, the Feather was connected to my workstation until 5:30 last night and shortly after that the workstation went into power save mode, at this point the battery attached to the feather kicked in. Once I resumed power saving on my workstation this morning (8:10am), the temperature and humidity results went nuts again.
Thought it may be a result of push back from the feather charging the battery, but I'm seeing the same results without battery. Pretty sure this worked originally, so not sure if library updates has caused the issue.
Thought it may be a result of push back from the feather charging the battery, but I'm seeing the same results without battery. Pretty sure this worked originally, so not sure if library updates has caused the issue.
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- bme280overnight.png (11.21 KiB) Viewed 107 times
Please be positive and constructive with your questions and comments.