Using this core with PlatformIO

What is PlatformIO?

PlatformIO is a free, open-source build-tool written in Python, which also integrates into VSCode code as an extension.

PlatformIO significantly simplifies writing embedded software by offering a unified build system, yet being able to create project files for many different IDEs, including VSCode, Eclipse, CLion, etc. Through this, PlatformIO can offer extensive features such as IntelliSense (autocomplete), debugging, unit testing etc., which not available in the standard Arduino IDE.

The Arduino IDE experience:

_images/the_arduinoide_experience.png

The PlatformIO experience:

_images/the_platformio_experience.png

Refer to the general documentation at https://docs.platformio.org/.

Especially useful is the Getting started with VSCode + PlatformIO page.

Hereafter it is assumed that you have a basic understanding of PlatformIO in regards to project creation, project file structure and building and uploading PlatformIO projects, through reading the above pages.

Current state of development

At the time of writing, PlatformIO integration for this core is a work-in-progress and not yet merged into mainline PlatformIO. This is subject to change soon.

If you want to use the PlatformIO integration right now, make sure you first create a standard Raspberry Pi Pico + Arduino project within PlatformIO. This will give you a project with the platformio.ini

[env:pico]
platform = raspberrypi
board = pico
framework = arduino

Here, you need to change the platform to take advantage of the features described hereunder. You also need to inject two PlatformIO packages, one for the compiler toolchain and one for the Arduino core package.

[env:pico]
platform = https://github.com/maxgerhardt/platform-raspberrypi.git
board = pico
framework = arduino
; note that download link for toolchain is specific for OS. see https://github.com/earlephilhower/pico-quick-toolchain/releases.
platform_packages =
    maxgerhardt/framework-arduinopico@https://github.com/earlephilhower/arduino-pico.git
    maxgerhardt/toolchain-pico@https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.3.1-a/x86_64-w64-mingw32.arm-none-eabi-7855b0c.210706.zip

When the support for this core has been merged into mainline PlatformIO, this notice will be removed and a standard platformio.ini as shown above will work as a base.

Selecting the new core

Prerequisite for using this core is to tell PlatformIO to switch to it. There will be board definition files where the Earle-Philhower core will be the default since it’s a board that only exists in this core (and not the other https://github.com/arduino/ArduinoCore-mbed). To switch boards for which this is not the default core (e.g. the standard board = pico), the directive

board_build.core = earlephilhower

must be added to the platformio.ini. This controls the core switching logic.

Flash size

Controlled via specifying the size allocated for the filesystem. Available sketch size is calculated accordingly by using (as in makeboards.py) that number and the (constant) EEPROM size (4096 bytes) and the total flash size as known to PlatformIO via the board definition file. The expression on the right can involve “b”,”k”,”m” (bytes/kilobytes/megabytes) and floating point numbers. This makes it actually more flexible than in the Arduino IDE where there is a finite list of choices. Calculations happen in the platform.

; in reference to a board = pico config (2MB flash)
; Flash Size: 2MB (Sketch: 1MB, FS:1MB)
board_build.filesystem_size = 1m
; Flash Size: 2MB (No FS)
board_build.filesystem_size = 0m
; Flash Size: 2MB (Sketch: 0.5MB, FS:1.5MB)
board_build.filesystem_size = 1.5m

CPU Speed

As for all other PlatformIO platforms, the f_cpu macro value (which is passed to the core) can be changed as documented

; 133MHz
board_build.f_cpu = 133000000L

Debug Port

Via build_flags as done for many other cores (example).

; Debug Port: Serial
build_flags = -DDEBUG_RP2040_PORT=Serial
; Debug Port: Serial 1
build_flags = -DDEBUG_RP2040_PORT=Serial1
; Debug Port: Serial 2
build_flags = -DDEBUG_RP2040_PORT=Serial2

Debug Level

Done again by directly adding the needed build flags. When wanting to define multiple build flags, they must be accumulated in either a sing line or a newline-separated expression.

; Debug level: Core
build_flags = -DDEBUG_RP2040_CORE
; Debug level: SPI
build_flags = -DDEBUG_RP2040_SPI
; Debug level: Wire
build_flags = -DDEBUG_RP2040_WIRE
; Debug level: All
build_flags = -DDEBUG_RP2040_WIRE -DDEBUG_RP2040_SPI -DDEBUG_RP2040_CORE
; Debug level: NDEBUG
build_flags = -DNDEBUG

; example: Debug port on serial 2 and all debug output
build_flags = -DDEBUG_RP2040_WIRE -DDEBUG_RP2040_SPI -DDEBUG_RP2040_CORE -DDEBUG_RP2040_PORT=Serial2
; equivalent to above
build_flags =
   -DDEBUG_RP2040_WIRE
   -DDEBUG_RP2040_SPI
   -DDEBUG_RP2040_CORE
   -DDEBUG_RP2040_PORT=Serial2

USB Stack

Not specifying any special build flags regarding this gives one the default Pico SDK USB stack. To change it, add

; Adafruit TinyUSB
build_flags = -DUSE_TINYUSB
; No USB stack
build_flags = -DPIO_FRAMEWORK_ARDUINO_NO_USB

Note that the special “No USB” setting is also supported, through the shortcut-define PIO_FRAMEWORK_ARDUINO_NO_USB.

Selecting a different core version

If you wish to use a different version of the core, e.g., the latest git master version, you can use a platform_packages directive to do so. Simply specify that the framework package (framework-arduinopico) comes from a different source.

platform_packages =
   framework-arduinopico@https://github.com/earlephilhower/arduino-pico.git#master

Whereas the #master can also be replaced by a #branchname or a #commithash. If left out, it will pull the default branch, which is master.

The file:// pseudo-protocol can also be used instead of https:// to point to a local copy of the core (with e.g. some modifications) on disk.

Note that this can only be done for versions that have the PlatformIO builder script it in, so versions before 1.9.2 are not supported.

Examples

The following example platformio.ini can be used for a Raspberry Pi Pico and 0.5MByte filesystem.

[env:pico]
platform = https://github.com/maxgerhardt/platform-raspberrypi.git
board = pico
framework = arduino
board_build.core = earlephilhower
board_build.filesystem_size = 0.5m
; note that download link for toolchain is specific for OS. see https://github.com/earlephilhower/pico-quick-toolchain/releases.
platform_packages =
    maxgerhardt/framework-arduinopico@https://github.com/earlephilhower/arduino-pico.git
    maxgerhardt/toolchain-pico@https://github.com/earlephilhower/pico-quick-toolchain/releases/download/1.3.1-a/x86_64-w64-mingw32.arm-none-eabi-7855b0c.210706.zip

The initial project structure should be generated just creating a new project for the Pico and the Arduino framework, after which the auto-generated platformio.ini can be adapted per above.