A nice in-depth post on the hardware too!
…Unlike the Raspberry Pi computer, the Pico is a microcontroller. Mostly this means it’s not running an operating system and instead can run simple code. They are also typically less powerful with only 256kb of RAM instead of Gigabytes for the bigger brother, and have a lower clock speed.
However, this also means the controller starts immediately running your code upon power up, and it does not have to share resources to maintain an underlying system. This results in low power consumption, making them appropriate for battery-powered use cases.
After blinking a few coloured LEDs, we found that we could use potentiometers to control how much electricity would go through the circuit. We could then read this value from a screen. With some tinkering, we made a calculator which would multiply two numbers which are set using the potentiometer…