bryancalisto / rusty-pi4

Bare metal Raspberry Pi 4 blinking LED program written in Rust

rusty-pi4

This repo contains a working version of the blinking LED 32-bit baremetal code inspired in the video Low Level Learning's BAREMETAL RUST Runs on EVERYTHING that can be run in the RPi 4.

I couldn't find a solid guide about it when doubts kicked in while I was trying to do it myself, so here I leave a guide about it that may clarify the path to others.

Main differences between the implementation in RPi 3 and RPi 4.

The processor

RPi 3 uses a Broadcom BCM2837 ARM Cortex-A53 and the RPi 4 uses a Broadcom BCM2711 ARM Cortex-A72. Both can run ARMv7 code. The main difference is the peripherals' starting address: For RPi 4, we use the 32-bit 'Legacy master addresses' starting at 0x0_FEnn_nnnn because 'Low Peripheral mode' is enabled by default for the Pi. See here, in the 'Address Map' section.

The boot files

In the RPi 4 you have to use the files that have the '4' suffix: fixup4.dat and start4.elf. You don't need bootcode.bin because that code is now stored in the onboard EEPROM. See here.

The kernel name

The kernel is expected to be called kernel7l.img (notice the 'l'). See here.