That cannot be it; nvs initialization is not asynchroneous so nvs is available when the initialization routine finishes. My bet is still that your program runs for a small while (less than 900ms, seemingly) between the flashing being done and your serial monitor starting. Flashing resets the chip af...

Check esp_timer, it should be easily able to give you 400Hz. You can also use one of the hardware timers;I think Arduino has support for those built-in.

Can I ask what you're trying to achieve here? On the ESP32 series, you're usually better off using one of the peripherals rather than trying to bitbang something. For instance, you may want to look at the RMT peripheral if you need to generate 'weird' signals.

I don't think you can, not without recompiling the ESP-IDF libraries Arduino uses. Is there any reason you need to? If you need high-resolution timer callbacks, it's usually better to use things like ESP-IDFs esp_timer rather than increasing the tick rate.

Not sure where you get that a timer group contains 4 timers. From the TRM: 'The ESP32 contains two timer modules, each containing two timers. '. In general, the gptimer driver abstracts away over this: if you ask it for a timer, it'll give you the first one that is free.

It's likely a buffer overflow or some other memory corruption somewhere, but between the magic values that you use (3? 2000? 2048?) I have a hard time squirreling out what's happening exactly.

Could it be that your code is running without you seeing it? Could be that between flashing and opening the monitor (which resets the processor), the CPU gets to execute code for a little bit.

Well that's an MCU without any connectivity, and is even less suited than what's out there already. Note that the intent of the P4 is for it to easily and transparently pair up with one of our C-series chips (e.g. the C3 or C6 or in the future the C5) allowing it to connect to things in the same wa...

I would just have a question before closing the topic, How can I configure this SPI communication to use DMA? What would be the maximum size of data I could send? You already have the answer to both questions in your code: you use SPI_DMA_CH_AUTO and set .max_transfer_sz to whatever the maximum is ...

Do you have an issue specific with the LEDC? If so, you can also use the MCPWM or the RMT, or even hack stuff up using e.g. I2s, to generate such a signal. If you specifically want to generate a signal using a software interrupt, it would really help if you would tell us why exactly. (And the answer...