Precision RTC Plug JNZ but you can also use

but you can also use plain perf-board for this purpose

0v - remember that it’s only good for up to 50 mA of load (that's fine for testing sketches if lightly loaded from added 'Plugs' and/or radio module on reduced transmit power)

A configurable shunt to switch the output voltage between 3

Plugs with additional connectors on them

The Bare ARM Blinker is an entry-level introduction to building neat functions using the 32bit ARM Cortex M0+ chip architecture

Precision RTC Plug JNZ but you can also useThe Precision RTC Plug is a small (21x35mm) board containing a low power real time clock with battery backup. It continues to track the time with second by second resolution while the attached node is sleeping or even powered off (with optional battery inserted). An I2C bus running at 3. 3V is used as interconnect, with all the power and signal lines brought out to to both sides of the board to allow daisy chaining with other I2C conformant boards.