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Side Quest: Raspberry Pi Pico 2 W

Table of Contents

Now that I finally have enough breadboards, I have set up my Raspberry Pi Pico 2 W as well. This is still highly experimental — you will need to fetch the latest code directly from the git repositories.

What doesn’t work #

First, a quick note on what does not work yet:

  1. The internal LED. This also applies to the original Raspberry Pi Pico W. The internal LED is connected to the WiFi module, and the binding for the WiFi module is still very experimental. Fortunately the Freenove Ultimate Starter Kit contains plenty of external LEDs, so I simply use those instead. (I have switched to using two external LEDs for the Pico 2 W examples.)
  2. The pico_bsp crate. Luckily we only need the main package from it, so I have copied pico.ads directly into our project. My fingers are itching to find a cleaner long-term solution. Because of this I have not created a separate pico_ada_c01_blink crate — we now use the light tasking runtime for all Pico 2 W projects. The light tasking runtime is better in every respect anyway.
  3. You cannot add Alire crates that contain a [[pins]] section to the main repository, as all [[pins]] entries are removed when preparing the pull request. Therefore, if you want to try the Pico 2 W examples, you need to download the full repository from https://sourceforge.net/projects/pi-ada-tutorial/files/Sources/ or clone it.

What needs changing #

The good news is that almost no code changes are required. The only modification you may want to make is to replace any reference to the internal LED with an external LED.

All other changes live in the project files. I have created new directories by copying the original pico_ada_ ones and renaming them:

  • pico_ada_c01_blink_lt → pico2_ada_c01_blink_lt
  • pico_ada_c02_button_and_led → pico2_ada_c02_button_and_led
  • pico_ada_c03_led_bar → pico2_ada_c03_led_bar

Don’t forget to rename the GNAT project file (.gpr) inside each directory so that it matches the new directory name.

GNUmakefile #

A simple search-and-replace is all you need. If you use GVim (as I do), just run these three commands:

:% substitute /\CPico_/Pico2_/ge
:% substitute /\Cpico_/pico2_/ge
:% substitute /\CRPI-RP2/RP2350/ge

If you are not using Vim, the three substitutions do the following:

  • Replace every occurrence of “Pico” with “Pico2”, preserving the original upper/lower case.
  • Replace every occurrence of “pico” with “pico2”, preserving the original upper/lower case.
  • Replace the board identifier RPI-RP2 with RP2350.

GNAT project file (*.gpr) #

Again, a quick search-and-replace:

:% substitute /\CPico_/Pico2_/ge
:% substitute /\Cpico_/pico2_/ge

For non-Vim users: simply replace every “Pico” with “Pico2” while keeping the original case.

Alire crate description (alire.toml) #

This file needs a few more changes. Here is a plain-English step-by-step guide for everyone:

  1. Remove the following three lines (or the entire sections they belong to):

    • pico_bsp
    • rp2040_hal.Use_Startup
    • rp2040_hal.Interrupts

  2. Perform these search-and-replace operations (case-sensitive where shown):

    • Replace "pico" with "pico2"
    • Replace "rp2040" with "rp2350"
    • Replace "rpi_pico" with "rpi_pico2"
    • Replace Pico_ with Pico2_ (preserving case)
    • Replace pico_ with pico2_ (preserving case)
    • Replace RPI-RP2 with RP2350
    • Replace _rp2040 with _rp2350

  3. Update the version of the HAL crate:

    • Change the version of rp2040_hal from "^2.7" to "^3.0.0-alpha1"

  4. Add a new [[pins]] section at the bottom of the file with the following content:

[[pins]]
rp2040_hal = { url='https://github.com/JeremyGrosser/rp2040_hal', branch='3.x' }
  1. Finally, add this line inside the [configuration.values] section:
rp2040_hal.device = "RP2350A"

Now, if you do use GVim (and why wouldn’t you?), I have a neat little function that does all of the above in one go. Just drop this into your ~/.vimrc or run it once in the alire.toml buffer:

function! Alire_Pico_To_Pico2()
    " Remove unwanted configuration entries
    %g/pico_bsp/                delete
    %g/rp2040_hal\.Use_Startup/ delete
    %g/rp2040_hal\.Interrupts/  delete

    " Perform all the renames
    %s/\C"pico"/"pico2"/ge
    %s/\C"rp2040"/"rp2350"/ge
    %s/\C"rpi_pico"/"rpi_pico2"/ge
    %s/\CPico_/Pico2_/ge
    %s/\Cpico_/pico2_/ge
    %s/\CRPI-RP2/RP2350/ge
    %s/\C_rp2040/_rp2350/ge

    " Update HAL version
    %s/rp2040_hal\s*=\s*"\^2\.7"/rp2040_hal = "^3.0.0-alpha1"/ge

    " Add configuration value for the new device
    /\[configuration\.values\]/ append
rp2040_hal.device               = "RP2350A"
.

    " Add the pins section for the bleeding-edge HAL
    /\[configuration\.values\]/ insert
[[pins]]
rp2040_hal = { url='https://github.com/JeremyGrosser/rp2040_hal', branch='3.x' }

.
endfunction

After defining the function, simply position the cursor anywhere in the alire.toml file and run :call Alire_Pico_To_Pico2() — and the file is instantly updated for the Pico 2 W. It really is that quick!

The magic part is the new [[pins]] section, which pulls in the latest “alpha1” version of the HAL directly from Jeremy Grosser’s repository. As I said — this is still highly experimental, but it works remarkably well so far.

Build and deploy #

Remember to run make clean (macOS / Linux) or nmake clean (Windows) before you build the first time. If you don’t have a make tool installed yet, simply delete the entire alire directory (I had to do this after copying the project folders to activate the [[pins]]).

Apart from that, everything works exactly as before — at least for the chapters we have covered so far. It may become a little more involved later in the series, but for now the transition is pleasantly smooth.

LED and Button

Update #

If you don’t want to copy then pico.ads file you can also use my experimental fork of pico_bsp.

[[depends-on]]
pico_bsp                        = "^3.0.0-alpha1"
rp2040_hal                      = "^3.0.0-alpha1"
light_tasking_rp2350            = "^15.2"

[[pins]]
pico_bsp                        = { url='https://github.com/krischik/pico_bsp',         branch='develop' }
rp2040_hal                      = { url='https://github.com/JeremyGrosser/rp2040_hal',  branch='3.x'     }

[configuration.values]
pico_bsp.device                 = "RP2350A"
rp2040_hal.device               = "RP2350A"
light_tasking_rp2350.Max_CPUs   = 2
light_tasking_rp2350.Board      = "rpi_pico2"

This fork also has a few other extras. Just remember that this is all still very experimental.