99% sure a measurement error. Make sure you have a good ground connection, and make your measurement loop as small as possible (=no long wire between ground and the probe, or the signal and the probe)

If anything, you shouldn't call any potentially 'long' / blocking things during the ESPNow callback. Normally, you'd quickly filter the package (as in discard it if it's uninteresting) and dump its relevant info in a freertos queue or something if you want to keep it, for another thread to process.

You can. I attached an example on how to do that here. Note that this code is ancient, it e.g. still uses the old make build system, so you may need to tweak it a bit, but the details should be there. In general, this is not implemented in esp-idf because 1. that clock stops in any sleep mode (and m...

0xcf is the first byte of the *encrypted* image format, but it looks like it's written via function calls that expect the *decrypted* image.

I think that code would crash: you're calling a blocking function in a critical section. In general: That sleep mode is not intended to manually call, to be honest; it's ideal for a RTOS idle scenario as the way it sleeps makes it trivial to implement, with the downside being that the savings are no...

If the JSON is a single key/value store, you'd probably best off using the NVS (or specifically for Arduino, the 'preferences' library) rather than a spiffs. Just take the keys that you would put into the JSON file and feed them into the Preferences lib instead.

Glad to hear it works. No need to mark the answer as accepted, the forum doesn't have functionality for that.

All of them do. FreeRTOS detects when there's nothing better to do and runs the 'idle' task. This will put the core to sleep until the next tick interrupt or any other configured interrupt happens. Note that the core is only clockgated, not powered down, and all peripherals including the radios stil...

Dependent on what configuration you need, nvs could also be a good place to store it.

If you need OTA, you need two OTA partitions, ideally of the same size. (The factory partition is not required for OTA, though, so unless you know you need a factory partition, you can convert that into an OTA partition, giving you two 1.5MiB-sized OTA partitions.) Do you need to store files into in...