RMT pins, how do I know which ones?

darkgiuseppe
Posts: 26
Joined: Fri Mar 11, 2022 3:57 pm

RMT pins, how do I know which ones?

Postby darkgiuseppe » Fri Mar 11, 2022 4:02 pm

Hello,

Getting to know the ESP32-S3 better (it's my first ESP32 chip I have ever played with) and getting used to everything. This might sound like a silly question but how do I know which pins are for which RMT channel? I know I can see the constants in my IDE such as RMT_CHANNEL_0 but I am not sure when physical pin it is on the ESP32-S3-DevkitC board. I have seen labeled pins online but I do not see anything labelled as RMT so far.

ESP_Sprite
Posts: 9312
Joined: Thu Nov 26, 2015 4:08 am

Re: RMT pins, how do I know which ones?

Postby ESP_Sprite » Sat Mar 12, 2022 2:44 am

Generally, most peripherals on the ESP32 series do not have dedicated pins. The chip has a GPIO matrix, which means you can effectively route any function to any GPIO pin. Even the pins that *are* indicated, tend to simply be the defaults. (Note that there are exceptions, e.g. SDIO and ADC, which do have dedicated pins, but these peripherals are a minority.)

darkgiuseppe
Posts: 26
Joined: Fri Mar 11, 2022 3:57 pm

Re: RMT pins, how do I know which ones?

Postby darkgiuseppe » Sat Mar 12, 2022 8:05 pm

Oh interesting. How do I find out the defaults for the RMT pins? I think I only want to use the GPIO matrix feature if I am stuck in a corner for rework.

ESP_Sprite
Posts: 9312
Joined: Thu Nov 26, 2015 4:08 am

Re: RMT pins, how do I know which ones?

Postby ESP_Sprite » Sat Mar 12, 2022 11:52 pm

There are no defaults and there is no way to route RMT that doesn't involve the GPIO matrix. It's generally not a complicated thing, though: if you use ESP-IDF, for instance, you simply tell the RMT driver which pin to use as a parameter in the initialization call.

darkgiuseppe
Posts: 26
Joined: Fri Mar 11, 2022 3:57 pm

Re: RMT pins, how do I know which ones?

Postby darkgiuseppe » Tue Mar 15, 2022 9:08 pm

O.o it's like magic lol

Okay thank you for this information.

Jeevan
Posts: 3
Joined: Thu Mar 17, 2022 4:58 pm

Re: RMT pins, how do I know which ones?

Postby Jeevan » Thu Mar 17, 2022 5:41 pm

Does it matter which channel we choose?
Also, I tried configuring the gpio through menuconfig but can't seem to navigate it well.
The purpose was to replicate the blink example sketch when they defined CONFIG_GPIO_LED and it was in the sdkconfig.h file with CONFIG_GPIO_LED set to 48(esp32s3).
So I was thinking setting the gpio through menuconfig would produce the same results in my sdkconfig.h file.
Is this right?

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