Raspberry PI Pico - Arduino API
On Friday I was receiving my Raspberry PI Pico and I had the opportunity to play around with it. Actually most of the time I spent reading the Manuals... The conclusion: interesting - but a little bit too complicated - So I was quite happy to read that Arduino plans to add an official support for this Microcontroller.
However I did not want to wait for the official support to be available, so as a temporary solution, I decided to make my own Arduino API availale as a separate project.
Design goals
- Provide a full implementation of the Arduino API
- Provide additioal easy to use C++ classes for the functionaity which is specific to the Pico
- Keep the pico specific build process using cmake
- Provide examples
Installation
-
First you need to install the Pico C Framwork. Please follow the instructions and do not forget to define the PICO_SDK_PATH environment variable.
-
Clone this project with
git clone https://github.com/pschatzmann/pico-arduino
- Define the environment PICO_SDK_ARDUINO_PATH variable to point to the project location.
- Build the arduino library (optional). The project already contains the compiled library. However I would recommend to rebuild it from the source.
To build the arduino library go to the pico-arduino/Arduino subdirectory
cd pico-arduino/Arduino
and execute the steps below:
mkdir build
cd build install
cmake ..
make
You can find the resulting library in the pico-arduino/lib directory.
Examples
Let's have a look at the blink example. It conisists of the source code blink.cpp
#include "Arduino.h"
// the setup function runs once when you press reset or power the board
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}
This looks like a standard Arduino sketch. Please note the following differences however:
- The sketch file name must end with .cpp and not .ino
- The
#include "Arduino.h"is mandatory - You need to provide a CMakeLists.txt file
To build the example go to the pico-arduino/examples/blink directory and execute the build steps:
mkdir build
cd build
cmake ..
make
The result can be found in the arduino/examples/blink/build directory.
Here is the list of the provided examples
The Pico has 2 processors, so here are the examples which use this Pico specific functionality:
And finally some other Pico specific functionality:
Documentation
The generated Class documentation can be found in the doc folder
Pinout
It helps to know the functions of the pins. Here is a copy of the pinout provided by the official Raspberry Pi Pico Documentation:
If a method is requiring a pin you can provide the GPIO number as integer or use the corresponding GP name as given in the sheet above.
The following calls are all identical:
digitalWrite(25, HIGH); // turn the LED on using integer
digitalWrite(GP25, HIGH); // the same with GP25 define
digitalWrite(LED_BUILTIN, HIGH); // the same with Arduino defines
digitalWrite(PICO_DEFAULT_LED_PIN, HIGH); // the same with Pico defines
Deploying a compiled Sketch
Deployment is very easy - just press the button on your Pico while plugging it to your computer via USB. This will automatically mount the Pico as external drive (RPI-RP2). Finally you just need to copy the generated uf2 file from your build directory to the drive.
That's it!
Project Status
- Basic Arduino API (e.g. String, Serial...) - done
- digital input/output API - done
- analog input/output API (PWM) - done
- Multiprocessor support: queue, semaphore - done
- tone - in progress
- PIO API class - in progress
- Arduino SPI API - open
- Arduino I2C API - open
- I2S API using PIO - open
- Software Serial using PIO - open
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