Just guessing here, as I'm not that familiar with the mqtt code, but are you sure the topic and data are zero-terminated? If not, the strcpy will copy lots of bytes, overwriting lots of static data.

You'd normally use a dedicated thread for reading the I2S peripheral, which then does whatever needs doing with the output data. You'd run other responsibilities in other tasks.

Yes. You'd have to forego anything that interfaces with the RTOS in the ISR, though.

That's an ESP8266 module, not an ESP32 one.

Yes, the RTC doesn't know the current time from CPU start, and it will reset when the chip is reset externally or the power goes away. Implementing deep sleep would be the thing to do. I think you can set the RTC manually using settimeofday(), by the way.

Any chance you can force a core dump, using e.g. a button irq or something?

Moved to the Arduino subforum.

1. What do you mean by 'TDK'? 2. That's pretty hard... the ESP32 accesses flash and PSRAM through more-or-less the same lines, so if you need to write directly to PSRAM, you either have to stop just about all processes in the ESP32, or you need to somehow disconnect the PSRAM chip from the ESP32. As...

How are your strings (like str_topic) allocated?

FWIW, you obviously can try to use the chips for anything you like if you so please, but you should know you're going a little bit against the architecture here... the Xtensa is quick because of lots of pipelining and a bunch of architectural details, but these same things make it slightly more expe...