A handy guide to getting started with the Raspberry Pi Pico
Nice little project, you could even do it with no extra components if you take the switch out and just make it timed. Here it is on Github OR you can see it in action here
Here it is on Github OR you can see it in action here
Pressing the BOOTSEL button on the pico board and plugging it in via USB will mount the pico as a mass storage device. You simply copy over a .uf2 file to change the firmware on your pico.
Reset Button Tip
You can wire a momentary switch between Run pin (pin 30) and ground to reset the Pico. You can also use this instead of unplugging and plugging back in to mount as USB storage. Here is a link to a demo and further info.
A good place to get started is micro python, or circuit python. You can also build your own firmware in C/C++ using the SDK.
Grab yourself the latest version of Micro Python in the form of a .uf2 file. You should be able to find it at https://www.raspberrypi.org/ then copy it onto the device that appeared when you plugged the pico in with the BOOTSEL button pressed.
The device will be unmounted and you now have the Micro Python firmware on your Pico.
Unlike CircuitPython you can't just drag python files over to it like a mass storage device. The quickest way to get started is using Thonny https://thonny.org/. This will let you run python line by line in REPL or run the code from the editor.
It will also allow you to save files onto the Pico as you can't just drag and drop or treat the Pico as a UB drive with MicroPython. If you dave a file named main.py this file will be run whenever the Pico is powered on.
Another option to attach to the Pico is via the USB connection using minicom. You Pico should be /dev/ttyACM0 or similar. If unsure then list the files in /dev and see which one is removed when you unplug your pico.
sudo apt install minicom
minicom -o -D /dev/ttyACM0Now you should be able to type python code and ctrl-d to reboot the Pico
>>> print("hello world")
hello world
>>>
MPY: soft reboot
MicroPython v1.13-290-g556ae7914 on 2021-01-21; Raspberry Pi Pico with RP2040
Type "help()" for more information.
>>>
ctrl-a then x to quit
Install
sudo apt install python3-pip
sudo pip3 install adafruit-ampy
ampy --port /dev/ttyACM0 put yourscript.py main.py
Copy files, or run script
ampy --port /dev/ttyACM0 run yourscript.pyIf you don't want to be tied to Thonny you can use rshell
sudo apt install python3-pip
sudo pip3 install rshell
rshell -p /dev/ttyACM0Type boards to list dev boards, repl boardname to enter REPL ctrl-x to exit REPL.
> boards
pyboard @ /dev/ttyACM0 connected Epoch: 1970 Dirs: /main.py /ssd1306.oy /ssd1306.py /pyboard/main.py /pyboard/ssd1306.oy /pyboard/ssd1306.py
> ls /pyboard
main.py ssd1306.py ssd1306.oy
>
Now you can copy files etc using cp mv mkdir rm etc.
Grab yourself the latest version of Circuit Python in the form of a .uf2 file. You should be able to find it at https://circuitpython.org/downloads then copy it onto the device that appeared when you plugged the pico in with the BOOTSEL button pressed.
The device will be unmounted and you now have the Micro Python firmware on your Pico.
You should see your pico mounted as a mass storage device. It will look like you just plugged in USB drive named 'CIRCUITPY' (You can rename this if you like or just leave it).
You can drag over a file called code.py and it will run the code in that file whenver that file is created, changed, or when the pico is powered on.
You will likely want to benefit from the many libraries available for CircuitPython. You can download these from https://circuitpython.org/libraries and add any you want to use in the /lib folder on your pico.
The MU code editor is tooled up to work with CircuitPython https://codewith.mu/
You can build your own .uf2 firmware using C/C++. You need to use the SDK, we used these instructions below for our youtube video walkthrough of the process.
On linux you need to make sure you have the correct tools
-
CMake - A great free tool to make your build system.
-
The GNU Arm Embedded Toolchain - Compiler, libraries and tools to build for the Arm processor.
-
Newlib - A C library & maths library for embedded systems.
We can easily install all 3 using the terminal.
sudo apt install cmake gcc-arm-none-eabi libnewlib-arm-none-eabiCD to your project folder where your code is. In our example our code is flash-led.c
#include "pico/stdlib.h"
int main() {
const uint LED_PIN = 25;
gpio_init(LED_PIN);
gpio_set_dir(LED_PIN, GPIO_OUT);
while (true) {
gpio_put(LED_PIN, 1);
sleep_ms(250);
gpio_put(LED_PIN, 0);
sleep_ms(250);
}
}Next in your project folder clone the Pico SDK repo
git clone https://github.com/raspberrypi/pico-sdk.gitIf you want to inclue TinyUSB and also avoid warning messages later.
cd pico-sdk
git submodule update --init
cd ..Copy this file to your project folder
cp pico-sdk/external/pico_sdk_import.cmake ./Create CMakeLists.txt
touch CMakeLists.txtThen edit the contents of CMakeLists.txt in this example our C code is in flash-led.c in the project folder
cmake_minimum_required(VERSION 3.12)
include(pico_sdk_import.cmake)
project(flash_led_project)
pico_sdk_init()
add_executable(flash_led
flash-led.c
)
target_link_libraries(flash_led pico_stdlib)
pico_add_extra_outputs(flash_led)It will need to know where to find the SDK we cloned from github so set this replacing the path to where you installed the sdk usding git clone.
export PICO_SDK_PATH=/home/pi/Desktop/dev/pico-sdkAlternatively you can add this line to CMakeLists.txt to fetch it from git. I like to do things manually so I know it's repeatable. In the future the git repo may change and my old code not work.
set(PICO_SDK_FETCH_FROM_GIT on)
mkdir build
cd build
cmake ..
make flash_ledYou should find flash_led.uf2 in your build folder. Congratulations you just built firmware you can copy to your Raspberry Pi Pico.
mkdir temp
cd temp
sudo apt install automake autoconf build-essential texinfo libtool libftdi-dev libusb-1.0-0-dev
git clone https://github.com/raspberrypi/openocd.git --recursive --branch rp2040 --depth=1
./bootstrap
./configure --enable-ftdi --enable-sysfsgpio --enable-bcm2835gpio
make -j4sudo apt install gdb-multiarch