I find this course at Cambridge to be a wonderful resource for bare metal programming on ARM (Raspberry PI): https://www.cl.cam.ac.uk/projects/raspberrypi/tutor

I find this course at Cambridge to be a wonderful resource for bare metal programming on ARM (Raspberry PI): https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/index.html https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/i... It starts off with booting a simple OS written in assembly from SD card, blinking LED and then continues to more advanced topics such as controlling the GPU/screen.