{file}
{tag=LED blinker}

\a[../../rpi-pico-w/upython/adc.py]: <analog-to-digital converter>.

The program continuously prints to the USB the value of the ADC on GPIO 26 once every 0.2 seconds.

The onboard LED is blinked as a <heartbeat (computing)>.

The hello world is with a <potentiometer>: extremes on GND and VCC pins of the Pi, and middle output on pin GIO26, then as you turn the knob, the uart value goes from about 0 to about 64k.

The 0 side is quite noisy and varies between 0 and 300 for some reason.

In <Ciro's ASCII art circuit diagram notation>:
``
RPI_PICO_W__gnd__gpio26Adc__3.3V@36
            |    |          |
            |    |          |
            |  +-+          |
            |  |            |
            |  |  +---------+ 
            |  |  |
         P__1__2__3
``


rpi-pico-w/upython/adc.py

{file}
{tag=LED blinker}

Same as the more generic <micropython/blink_gpio.py>{file} but with the onboard LED added.


rpi-pico-w/upython/blink_gpio.py

{file}
{tag=LED blinker}

Blink on-board <LED>. Note that they broke the LED hello world compatibility from non-W to W for God's sake!!!

The <MicroPython> code needs to be changed from the <Raspberry Pi Pico 1>, https://forums.raspberrypi.com/viewtopic.php?p=2016234#p2016234 comments:
> Unlike the original Raspberry Pi Pico, the on-board LED on Pico W is not connected to a pin on RP2040, but instead to a GPIO pin on the wireless chip. 


rpi-pico-w/upython/blink.py

{file}
{tag=LED blinker}

This example attempts to keep temperature to a fixed point by turning on a fan when a <thermistor> gets too hot.

You can test it easily if you are not in a place that is too hot by holding the <thermistor> with your finger to turn on the fan.

You can use a simple <LED> to represent the fan if you don't have one handy.

In <Ciro's ASCII art circuit diagram notation>:
``
            +----------FAN-----------+
            |                        |
            |                        |
RPI_PICO_W__gnd__gpio26Adc__3.3V@36__gpio2
            |    |          |
            |    |          |
            |    |          |
            |    +-THERMISTOR
            |    |
            |    |
            R_10-+
``


rpi-pico-w/upython/thermistor_fan_control.py

{file}
{tag=LED blinker}

Any `print()` command ends up on the USB, and is shown on the computer via programs such as <ampy> get back.

However, you can also send data over actual UART.

We managed to get it working based on: https://timhanewich.medium.com/using-uart-between-a-raspberry-pi-pico-and-raspberry-pi-3b-raspbian-71095d1b259f with the help of a <DSD TECH USB to TTL Serial Converter CP2102> just as shown at: https://stackoverflow.com/questions/16040128/hook-up-raspberry-pi-via-ethernet-to-laptop-without-router/39086537#39086537 for the RPI.

We connect Pin 0 (TX), Pin 1 (RX) and Pin 2 (GND) to the DSD TECH, and the USB to the <Ubuntu 25.04> host laptop.

Then on the host laptop I run:
``
screen /dev/ttyUSB0 9600
``
and a counter shows up there just fine!


rpi-pico-w/upython/uart.py

{c}

= Blinky
{synonym}
{title2}

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.


Ciro Santilli @cirosantilli 37

 Tagged: LED blinker