When you’re debugging a board which has an ESP32, Raspberry Pi, or Arduino, it’s easy to slap ... A resistor and an LED will often suffice. Powering the LED means one thing and not powering ...

Here’s a no-PCB Arduino ... and an LED. This is modeled after the Lilypad hardware, and fits nicely on top of the plastic case of the microcontroller, allowing it to be used in a breadboard ...