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I've been playing with the Baking Pi tutorials, getting assembly code to work on the [bare metal] Pi 1 (BCM2835).

I'm now interested in adapting the code to work on the Pi 4 BCM2711 but I'm struggling with updating the addresses. I found a thread describing the Different addressing systems but I'm still not sure which part of the data sheet I need to refer to in order to update the (very simple) assembly code to work with the latest Pi.

Which GPIO address do I need for the LED on the Pi 4? I couldn't find it from a look through the datasheet (but I'm relatively inexperienced with this)!!

Any hints to help me get to the point where I can solve it would be appreciated!

moo
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The other answers claiming that the ACT_LED on the pi4 is not connect to the gpio is wrong. However, this was true on a previous version of the pi. One of the 3 series boards. (likely the source of confusion)

The LED is not part of the SOC so you won't find documentation for it there. However from the linux dts provided by broadcom we have... (https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/bcm2711-rpi-4-b.dts#L30-L33)

That the LED is connected to GPIO42 and is active high, so writing a non zero value to it should turn it on.

Myles
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