AAPen Forth for the Raspberry Pi Pico2

This is an experiment in porting aapenforth to the raspberry pi pico2.

Building

You will need a full pi pico gcc build enviornment. See env.sh for the environment variables/directories you will need.

To set up the build directory, simply run the setup.sh script:

$ ./setup.sh

Once you've done that you can cd to the build2 directory and run make.

Running on hardware (the hard way)

The simplest way to get aapen running on a pico (a pico2! aka the rp2350) is to connect the pico to your computer via USB while holding down the button on the board while you do the connecting.

This will make the pico show up as a USB drive. Simply copy the firmware--the file that ends in .uf2 to the new drive. This should cause the board to reboot, the drive to disappear and the firmware to run.

Debugging on hardware

For development you are going to need an interactive in-chip solution. This you can do by buying a pico debug probe.

Alternatively you can fashion a debugprobe from yourself from a second pico as documented in Appendix A of the Pico Getting started guide. Note that the debugprobe firmware for that second pico is here.

You will also need a custom version of openocd to do the in-chip debugging, which you can build yourself. This is what it looks like using a PI5 as a development machine:

git clone https://github.com/raspberrypi/openocd.git --branch picoprobe --depth=1 --no-single-branch
cd openocd/
./bootstrap 
./configure --enable-picoprobe
make -j4 --no

Once that is built you can start up the openocd that you just built and connect to the pico:

src/openocd -s tcl -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "adapter speed 5000"

This should open a remote gdb port on 3333.

In a different window start gdb:

gdb aapen_pico.elf --ex "target extended-remote :3333"

And you are off and debugging.

Repo Structure

Code in this repo uses the .syntax unified directive.

/pico-asm
|
|___/source
|   |___/blink_demo        // Flash the Pico LED.
|   |   |___CMakeLists.txt  // App CMake config file
|   |   |___main.S          // App assembly source
|   |   
|   |___/aapen_forth
|   |   |___CMakeLists.txt  // App CMake config file
|   |   |___jonesforth.s    // Modified copy of the original jonesforth.s
|   |   |___main.S          // App assembly source
|   |
|   |___/common             // Common source files from Tony Smit.
|       |___sdk_inlines.c   // Wrappers for SDK inline C functions
|
|___CMakeLists.txt          // Top-level project CMake config file
|___pico_sdk_import.cmake   // Raspberry Pi Pico SDK CMake import script
|___deploy.sh               // Build-and-deploy shell script
|
|___README.md
|___LICENSE.md

Credits

The source/aapen_forth/joinesforth.s is derived from here.

We are grateful Tony Smith for the build scripts and directory structure. See this github project. The build code that we adopted is © 2022, Tony Smith, and is licensed under the terms of the MIT Licence