Microdot Webserver on ESP32S3 Interfering with SPI Communication

[hstarmans]

I'm encountering timing issues using hardware SPI communication, on a ESP32S3 with microdot.
I have a loop which writes over SPI, this loop no longer works from microdot if I also activate with_websocket and with_sse

[miguelgrinberg]

@hstarmans Maybe your microcontroller's CPU is not fast enough to keep the SPI communication and at the same time handle the web server load. Are you using software SPI or hardware SPI? You should use hardware based SPI if you aren't, as that will free up some cycles in the CPU.

[hstarmans]

I am using hardware SPI, but not the latest ESP_IDF, micropython and microdot. I will see if that resolves the issue.

[miguelgrinberg]

The other option that you can explore is to run the web server and the code that controls your device on separate threads. I believe the ESP32 has two cores, so it should be possible to run two independent threads. What I don't remember is if MicroPython on that platform has thread support enabled, so you'll need to check that.

[hstarmans]

I lowered my SPI frequency and this resolved the issue. Not all actions happen within DMA, e.g. select pin high and low.
This likely creates additional frequencies which my FPGA using my custom Amaranth HDL can no longer handle.

Thank you @miguelgrinberg !

PS. Other options tried

• moved my code from idf v5.2.1 to v5.4.0 (did not resolve issue)