Bare Metal coding examples

A repo with coding examples used for a bare metal coding course using:

• CPUlator de1soc simulator - https://cpulator.01xz.net/?sys=arm-de1soc
• Wokwi Raspberry Pi Pico simulator - https://wokwi.com/pi-pico
• and a real Raspberry Pi Pico version 1, RP2040

Run in a GitHub codespace?

From this GitHub repo - open a codespace, then try these commands:

$ sudo apt update
$ sudo apt install build-essential gcc-arm-none-eabi gdb-multiarch

Run in a Docker container?

Try something like this:

$ git clone https://github.com/olvemaudal/baremetal.git
$ cd baremetal
$ docker build -t devbox .
$ docker run --rm -it -v ${PWD}:/workspace devbox

Compile and run the display demo app on the de1soc simulator

To create a small demo app for the de1soc, try some of these commands:

$ cat de1soc-display-demo.S
$ make de1soc-display-demo
$ arm-none-eabi-objdump -d de1soc-display-demo.elf

Then download the .elf file, to your disk, and upload it to the CPUlator.

Upload source code to the CPUlator editor

While experimenting with the CPUlator you may just write or paste stuff directly into the editor. Eg, try to paste

de1soc-shownumber.c

into the editor and click compile and load, and then continue.

Bare metal coding on the RP2040

We will now use a public github repo to demonstrate how to create a simple blinky app on the Raspberry Pi Pico RP2040. Try these commands:

$ git clone https://github.com/vxj9800/bareMetalRP2040.git
$ cd bareMetalRP2040
$ git submodule update --init
$ cd 01_bootupBlinky/
$ make
$ ls -al boot2Blinky.uf2

Plug in the Pico to your USB port while holding the BOOTSEL button so that it shows up as a USB storage. Then copy the uf2 file onto the drive, and watch the Pico reboot and start to blink.

Compile, link and run primedemo

This is an attempt to show a complete C program, including testing and linking. Try these commands:

$ gcc -c primelib.c
$ gcc primelib_tests.c primelib.o
$ ./a.out
All tests passed
$ gcc -o primedemo primedemo.c primelib.o
$ ./primedemo

Links and resources

• HackadayU: Raspberry Pi Pico and RP2040 (YouTube)
• RP2040 - Introduction to Assembly Language (YouTube)
• https://github.com/raspberrypi/pico-bootrom-rp2040
• https://github.com/raspberrypi/pico-sdk
• https://datasheets.raspberrypi.com/rp2040/rp2040-datasheet.pdf
• https://datasheets.raspberrypi.com/pico/getting-started-with-pico.pdf
• https://cpulator.01xz.net/?sys=arm-de1soc
• https://fpgacademy.org/Downloads/DE1-SoC_Computer_ARM.pdf
• https://developer.arm.com/documentation/dui0662/latest/
• Assembly Language Programming with ARM https://www.youtube.com/watch?v=gfmRrPjnEw4
• https://godbolt.org/
• Reintroduction to C https://www.youtube.com/watch?v=Kq7WIexp6JU
• olvemaudal.com