3 ms·

I'd be super curious to see how the accuracy changes with averaging out/low-pass filtering the measurements. Accuracy usually improves proportional to sqrt(N) w

I'd be super curious to see how the accuracy changes with averaging out/low-pass filtering the measurements. Accuracy usually improves proportional to sqrt(N) when you take N samples so your higher precision desire might just be a bit of code to write. The other side of it though is that you're starting to get down into the "everything needs to be temperature controlled" region as you squeeze that precision number. FR-4 and copper have thermal expansion coefficients around 15-20ppm/C. If I'm doing this mental math correctly, a 5 deg temperature rise would make a 1m long piece of FR4 expand by 0.1mm, or a 10cm piece of FR4 expand by 0.01mm.

foobarian 2y ago
One time I wanted to demonstrate thermal expansion to my kid (1st grade or so) so I made some marks with a steel ruler and put it in the freezer. Imagine my surprise when we took it out and there was no perceptible difference :-D
- dekhn 2y ago
  did you measure the freezer after? It expanded :)
satiric 2y ago
With some microcontrollers you can do this "averaging out" just by changing ADC parameters, you don't even have to write the low-pass-filter code.
- auxym 2y ago
  That is specifically sigma-delta type ADCs: https://www.analog.com/en/resources/technical-articles/sigmadelta-adcs-tutorial.html https://www.analog.com/en/resources/technical-articles/sigma...
  - magicalhippo 2y ago
    No, several MCUs, like a lot of STM32s, support hardware oversampling with optional division. Here's[1] a document describing it for the L0 and L4 series, which like most of the STM32 series have SAR[2] ADCs. [1]: https://www.st.com/resource/en/application_note/an4629-adc-hardware-oversampling-for-microcontrollers-of-the-stm32-l0-and-l4-series-stmicroelectronics.pdf https://www.st.com/resource/en/application_note/an4629-adc-h... [2]: https://en.wikipedia.org/wiki/Successive-approximation_ADC https://en.wikipedia.org/wiki/Successive-approximation_ADC

foobarian 2y ago

One time I wanted to demonstrate thermal expansion to my kid (1st grade or so) so I made some marks with a steel ruler and put it in the freezer. Imagine my surprise when we took it out and there was no perceptible difference :-D

dekhn 2y ago
did you measure the freezer after? It expanded :)

satiric 2y ago

With some microcontrollers you can do this "averaging out" just by changing ADC parameters, you don't even have to write the low-pass-filter code.

auxym 2y ago
That is specifically sigma-delta type ADCs: https://www.analog.com/en/resources/technical-articles/sigmadelta-adcs-tutorial.html https://www.analog.com/en/resources/technical-articles/sigma...
- magicalhippo 2y ago
  No, several MCUs, like a lot of STM32s, support hardware oversampling with optional division. Here's[1] a document describing it for the L0 and L4 series, which like most of the STM32 series have SAR[2] ADCs. [1]: https://www.st.com/resource/en/application_note/an4629-adc-hardware-oversampling-for-microcontrollers-of-the-stm32-l0-and-l4-series-stmicroelectronics.pdf https://www.st.com/resource/en/application_note/an4629-adc-h... [2]: https://en.wikipedia.org/wiki/Successive-approximation_ADC https://en.wikipedia.org/wiki/Successive-approximation_ADC