Download program notes:

1. Download the program must use the interface on the micro:bit board. The interface on the expansion board cannot download the program.

2. No matter whether the micro:bit board is plugged into the expansion board, the program can be downloaded normally.

3. When the micro:bit board is plugged into the expansion board, the program can be downloaded normally regardless of whether the expansion board is turned on or off.

As shown in the figure below, the program can be downloaded in two ways.