ESP32 Adc not linear and noisy

fritsthecat

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« on: September 11, 2018, 12:51:13 12:51 »

Hi Everyone,

I'm experimenting with the ESP32 and I observe that the ADC is not terribly linear and pretty noisy. I need to filter it to have a decent and repeatable reading.

I don't know if someone else is experimenting that.

Thanks


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gan_canny

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Re: ESP32 Adc not linear and noisy

« Reply #1 on: September 11, 2018, 04:59:29 16:59 »

The esp32 has varying power demands due to transmission of WiFi. The power supply has to be beefy and as smooth as can be.
Most buy the dev boards with the 5v micro usb supply and the usb to serial controller on board.The ADC is relative to the supply voltage and any fluctuation will make the results variable. These dev boards work well but not so much for precision ADC.
The esp32 has dual MCU's ( one devoted to WiFi) and avoids the issue that earlier esp8266 would commandeer CPU cycles and interfere with predictable timing as well as also have the power fluctuations


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Sideshow Bob

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Re: ESP32 Adc not linear and noisy

« Reply #2 on: September 12, 2018, 10:38:23 10:38 »

Have you read this
https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/adc.html


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