ESP32 Forum

Hi,

Is there any example for the RMT simple callback encoder: https://docs.espressif.com/projects/esp ... ck-encoder? From the documentation, I still don't fully understand how the encoder callback works, so I'd love to see a working example. More specifically, I am interested in generating a "long" waveform using RMT, which means it needs to be transmitted in chunks. In the doc,

If the space is not enough for the callback to encode something, it can return 0 and the RMT will wait for previous symbols to be transmitted and call the callback again, now with more space available.

Does that mean I have filled up/encoded a chunk of data, I need it transmit it first, then reset the encoder? then repeat? Or what are the steps I need to do? Any pseudocode on how I can use the simple callback encoder for this would be greatly appreciated as well!

Thanks!

The driver comes with this example, hope that helps.

In general, the callback you provide will get called whenever there is some RMT memory that needs filling: in the callback, you calculate the next bit of your waveform and put it in the provided memory. The provided amount of memory can be anywhere between 1 entry and the maximum buffer the RMT can give you. If the amount of memory is too little (for instance, you can only calculate your waveform in increments of 2 RMT entries), your callback can return 0 and it will be called again later when there is more RMT memory available.