The Feather M0 can be used in debug mode using the SEGGER J-LINK programmer. It needs just a little extra effort to get set up. On the bottom side of the feather M0 (this is the Bluefruit LE model) there are exposed pads for the SWCLK and SWDIO pins which are required for JTAG programming. The SWCLK and SWDIO are actualy in two places on the bottom (use the green circles above) and avoid the red crossed out square pads.
These four pins must be connected to the Segger J-Link debugger along with a USB cord to power the circuit.
- Feather M0 [pin2] (Vcc) J-Link SWD [pin 1] (Vcc)
- Feather M0 [pin3] (GND) J-Link SWD [pin 3,5,9] (GND)
- Feather M0 [SWCLK] J-Link SWD [pin 4]
- Feather M0 [SWDIO] J-Link SWD [pin 2]
Making a custom featherwing board will be much more convenient than manually wiring each connection into the J-Link 2x10 header.