Writing audio to the SD card is very important to some users of the Tympan. Everyone wants to be able to have confidence that the audio written to the SD card is continuous, with no drop-outs or other kinds of “hiccups”. It turns out that, as long as your Tympan sketch is not using 100% of the CPU, the most important factor for ensuring smooth writing to the SD card is the specific SD card that you use. Low quality SD cards will not allow you to write audio smoothly.
As of writing this (June 2021), we always use SanDisk Ultra 32GB or SanDisk Extreme 32GB. The Ultra is what we have been using since 2018. The Extreme is what I bought when I recently had difficulty getting the Ultra. I’ve only ever used the 32GB versions.
There may be better choices now.
If you wanted to evaluate your own SD card, I wrote a Wiki page in the Tympan_Library repository. I am not an expert in this matter, so please let me know how to do it better!
Here’s the page: Evaluating SD Card Performance · Tympan/Tympan_Library Wiki · GitHub