At Adafruit, we really like the UF2 bootloader for installing software like CircuitPython on microcontrollers. UF2 allows you to drag-and-drop UF2 files and has a nice LED/NeoPixel indicator. No special DFU/firmware-updater software is required and you can use any computer to program a UF2-bootloader device. Once installed, you can access the UF2 bootloader by clicking the reset button twice in a row.

But what do you do with a fresh chip, or if the UF2 bootloader on your device has become corrupted? This guide will walk you through the steps of installing the UF2 bootloader using the ROM bootloader built into all RT10xx chips using software called sdphost or sdphost.exe on your PC, Mac, or Raspberry Pi.