This is weird. Point your phone's camera at the IR LED of a M5Stick or M5Stack that has the IR LED. Even just after a reboot, it seems to be glowing.

I cannot use the built-in "ir" object because it implements NEC protocol, which is not what I need. I need to generate a 40KHz pulse train for SIRC protocol

Taking manual control over the LED by deinitializing the RMT, I can turn off the pin using machine.Pin

But after reinitializing RMT module, the LED starts to glow again.

I am trying code that looks like

>>> rmt.loop(True)
>>> rmt.write_pulses([1, 100000], start=0) # this should make the LED dim

and

>>> rmt.loop(True)
>>> rmt.write_pulses([1, 100000], start=1) # this should make the LED bright

The weird thing is that one of these should make the LED appear off, or at least dim. The opposite snippet should make the LED appear very bright. This is not the case. I see no change in brightness

What am I doing wrong?

Has anybody successfully used the IR LED for anything? The MicroPython version implemented in UIFlow is extremely old and won't match the latest documentation, the best documentation is actually this particular commit in the official ESP32 port of MicroPython https://github.com/micropython/micropython/blob/1678f417445703750e187b1b8a83c8c3e0e3796f/ports/esp32/esp32_rmt.c

oh and in case anybody needs to know, to deinitialize the RMT because you can't use the settings M5Stack is forcing upon you, I'm using this

        try:
            ir.__dict__['_tx_encode']._rmt.deinit()
            del ir.__dict__['_tx_encode']._rmt
            del ir
        except:
            pass