The cambridge tutorial is armv6 assembly only though. Which is kinda neat to poke around with, but not that much fun (imo). But doing baremetal for the raspberry is fun, just because it is a different architecture. The only problem I had with it was that the bcm-datasheet felt not very nice. It's kind of hard reading yourself through this. Or maybe it was so hard, because the topic in itself is pretty complex
https://news.ycombinator.com/item?id=16180975
https://jsandler18.github.io/
Also there are a few other things which come in handy like those two:
https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/
https://wiki.osdev.org/Raspberry_Pi_Bare_Bones
The cambridge tutorial is armv6 assembly only though. Which is kinda neat to poke around with, but not that much fun (imo). But doing baremetal for the raspberry is fun, just because it is a different architecture. The only problem I had with it was that the bcm-datasheet felt not very nice. It's kind of hard reading yourself through this. Or maybe it was so hard, because the topic in itself is pretty complex