J7 header

Eight free GPIO plus VSYS and ground on a 2.54 mm strip along the top edge.

Connector: 1×10, 2.54 mm
GPIO: 8 free
Power: VSYS + GND
Edge: Top

J7 runs along the top edge, exposing every GPIO the badge does not otherwise spend. Four of them double as the JTAG pins, so a debugger can go straight onto the header.

Pin 9 is VSYS rather than a regulated rail — whatever the power path is currently delivering, USB 5 V or battery voltage, after the ON/OFF switch. Regulate it yourself if your add-on needs something specific.

GPIO47 and GPIO48 used to be on this header. They now drive the microphones, so v1 carries 8 GPIO instead of 10.

Pins

Pin	Net	Role	Function
1 · GPIO17	IO17	J7	Free GPIO (ADC2_CH6).
2 · GPIO18	IO18	J7	Free GPIO (ADC2_CH7).
3 · GPIO21	IO21	J7	Free GPIO.
4 · GPIO38	IO38	J7	Free GPIO.
5 · GPIO39	IO39	J7	Free GPIO (JTAG MTCK).
6 · GPIO40	IO40	J7	Free GPIO (JTAG MTDO).
7 · GPIO41	IO41	J7	Free GPIO (JTAG MTDI).
8 · GPIO42	IO42	J7	Free GPIO (JTAG MTMS).
9 · —	VSYS	POWER	System rail before the 3V3 LDO, after the ON/OFF switch.
10 · —	GND	POWER	Ground.

Parts

J7 Conn_01x10, 2.54 mm Expansion header