pico-arduino-compat

A compatibility layer that allows the use of Arduino libraries with the Pico C/C++ SDK.

Installation

Clone the pico-arduino-compat repository

git clone https://github.com/fhdm-dev/pico-arduino-compat.git

Get the arduino-pico submodule

cd pico-arduino-compat
git submodule update --init arduino-compat/arduino-pico

How to include an Arduino library into an existing project

First find the library from the list here. Take note of the ID and the cmake target name.

Get the submodule for the library and dependent libraries

# cd into libs/<id>
# where id is the library ID you found previously
# eg.
cd libs/adafruit-ssd1306
./init.sh

In your project's CMakeLists.txt file, add the library directory as a subdirectory.

eg.

add_subdirectory(/home/fhdm-dev/pico/pico-arduino-compat/libs/adafruit-ssd1306)

Add the library target name to target_link_libraries. Note that the target names all begin with 'pac-'

eg.

target_link_libraries(boom
  pico_stdlib
  pac-adafruit-ssd1306
)

Arduino Global Variables

The table below shows how the Arduino global variables such as SPI, Wire, Serial etc map to Pico peripheral instances and GPIOs

Arduino Global Variable	Pico Peripheral Instance	GPIOs
SPI	spi0	16,17,18,19
SPI1	spi1	12,13,14,15
Wire	i2c0	4,5
Wire1	i2c1	10,11
Serial	Uses stdio	USB or 0,1
Serial1	uart0	0,1
Serial2	uart1	8,9

Compatibility

Arduino libraries that rely on architecture specific code such as direct register access will not work.

Directory structure

The directory structure of this repository is as follows:
arduino-compat: The compatibility layer
libs: The Arduino libraries and associated CMakeLists.txt files and examples
pico-libs: The C/C++ wrappers for the Arduino libraries

FAQ

How is pico-arduino-compat different from the Arduino RP2040 mbed core or the Arduino-Pico core?

Those cores allow you to use the Arduino IDE to program the Pico/RP2040. pico-arduino-compat is for using Arduino libraries with the Pico C/C++ SDK.

Can Arduino sketches be used with pico-arduino-compat?

If the sketch doesn't use architecture specific code then then it should run with a little modification. eg. See libs/liquidcrystal/pico-sdk-examples

Do applications using pico-arduino-compat run slower or use more resources?

Probably! You're better off using a library specifically written for the Pico C/C++ SDK. However if nothing is available and you just want to get something working quickly then pico-arduino-compat might be useful.

Do Arduino Libraries need to be modified to work with pico-arduino-compat?

Some don't. Some probably do. Some probably wont work at all.

If the library list shows an error status does that mean the library can't be used with the Pico C/C++ SDK?

Not necessarily. The fix might be as simple as adding a dependency in the CMakeList.txt file. If it is, let me know!

If the library list shows an OK status does that mean the library has been tested?

No. It just means that the source files compiled. Only a small number of the libraries have been tested on a device.

How did you choose which Arduino libraries to include?

The libraries are those listed in the Arduino reference documentation. I simply scraped the relevant web pages to get the required information and generated the CMakeList.txt files from that.

Can I only use a library if it is in the 'list of libraries'?

No. To use a different library, just add the arduino-compat directory and arduino-compat target to your CMakeLists.txt file. No guarantees it will work tho'!

Acknowledgments

Much of the code uses earlephilhower's Pi Pico Arduino core.