nRF

Nordic chips with BLE as the point. The BBC micro:bit is the board people meet first. Docs: nrf quickref and the micro:bit docs.

Boards

micro:bit v1 / v2
Nano 33 BLE
XIAO nRF52
micro:bit playground

micro:bit versus generic nRF

micro:bit firmware includes the 5×5 matrix, buttons and the classroom helpers. A generic nRF52 board gives you machine and bluetooth without the matrix API. Do not mix the two firmwares.

Playgrounds: v1 heart, v2 heart.