picotool 2025-07-26
Tested on Ubuntu 25.04,
sudo apt install libusb-1.0-0-dev
git clone https://github.com/raspberrypi/pico-sdk
git clone https://github.com/raspberrypi/picotool
cd picotool
git checkout de8ae5ac334e1126993f72a5c67949712fd1e1a4
export PICO_SDK_PATH="$(pwd)/../pico-sdk"
mkdir build
cd build
cmake ..
cmake --build . -- -j"$(npro)" VERBOSE=1
and the executable is there under build/picotool so copy it somewhere in your PATH like:
cp picotool ~/bin
and then trying to use a Zephyr example:
sudo ~/bin/picotool load -f build/zephyr/zephyr.uf2
fails with:
No accessible RP2040 devices in BOOTSEL mode were found
TODO: how to avoid that? youtu.be/tRXLxrtfU_s?t=207 gives a workaround if you are using the Pico SDK by adding to CMakeLists.txt:
pico_enable_stdio_usb(blink 1)
but how to do it in Zephyr? Video description says:
make sure that your program initializes the USB code via a call to "stdio_init_all()".
but again how to do that from Zephyr? It appears that this only works if the code currently running has support for the feature:
Video 1.
Never unplug your Raspberry Pi Pico again by deltocode
. Source.
The Zephir LED blinker example does not work on the Raspberry Pi Pico W because the on-board LED is wired differently. But the hello world works and with:
screen /dev/ttyUSB0 115200
host shows:
*** Booting Zephyr OS build v4.2.0-491-g47b07e5a09ef ***
Hello World! rpi_pico/rp2040
Nice!
Raspberry Pi Pico 1 2025-07-26
This section is about the original Raspberry Pi Pico board. The "1" was added retroactively to the name as more boards were released and "Raspberry Pi Pico" became a generic name for the brand.
Jerry Chun Shing Lee 2025-07-26
Figure 1.
Jerry Chun Shing Lee in blue tie at the unveiling of Leonardo da Vinci's 'Salvator Mundi' painting at the Christie's showroom in Hong Kong on Oct. 13, 2017
. Source.
Zephyr hello world example Created 2025-07-26 Updated 2025-07-27
Uses printf to print some bytes somewhere, usually the first UART of the board.
Zephyr blinky example Created 2025-07-26 Updated 2025-07-27
Blinks the on-board LED if the board has one.
Does not work on:
Note that the LED blinker example does not work on the Raspberry Pi Pico W, see also: Run Zephyr on Raspberry Pi Pico W.
You can speed up the debug loop a little bit by plugging the Pi with BOOTSEL selected, and then running:
west flash --runner uf2
This flashes the image, and immediately turns off BOOTSEL mode and runs the program.
However to run again you need to unplug the USB and re-plug with BOOTSEL again so it is still painful.
Video 1.
Let's run Zephyr RTOS on Raspberry Pi Pico. Ep.1 by Mr. Green's Workshop
. Source.
Then ignore the other steps from the tutorial, as theese use the picozero package, which is broken with this error: github.com/raspberrypilearning/getting-started-with-the-pico/issues/57
AttributeError: module 'pkgutil' has no attribute 'ImpImporter'. Did you mean: 'zipimporter'
and uses picozero specific code. Rather, just use our examples from rpi-pico-w.
LED blinker 2025-07-26
This is the hello world program of microcontrollers: blinking and LED! Many boards have an on-board LED, making this a convenient hello world that does not require any external components.
Type of hello world 2025-07-26
Other programs that can be considered "hello worlds" in different contexts:
harmonic.fun 2025-07-26
Not a clue to what they do more precisely, but it sure sounds fun.

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