NeoPixels and other addressable LED strings are a technology that have made vibrant, glowing LED projects accessible to all. Of course, it’s nice to be able to simulate your new glowy project in software before you actually set up your LED strings in practice. [Randy Elwin]’s NeoPill simulator can help with that!
The NeoPill consists of an STM32F103 development board, into which one simply hooks up a NeoPixel data line. The microcontroller then decodes the data using a combination of its onboard timers and SPI hardware. This data is then passed to a PC over the onboard USB serial connection, where it’s decoded by a custom Python app. The app takes the data and displays the pixels on screen, so you can verify they operate as expected before you hook up a single real LED.