1.7 Xplained Pro Standard Extension Header

All Xplained Ultra and Curiosity Ultra Kits have many dual-row, 20-pin, and 100 mil extension headers. Xplained Ultra and Curiosity Ultra MCU boards have male headers, while Xplained Ultra extensions have their female counterparts as shown in the following figure.

Note: All pins are not always connected.

The extension headers can be used to connect a variety of Xplained Pro extensions to Xplained Ultra and Curiosity Ultra MCU boards, or to access the pins of the target MCU on Xplained Ultra MCU or Curiosity Ultra boards directly.

All connected pins follow the defined pinout description as shown in the following table.

Table 1-7. Xplained Pro Standard Extension Header
Pin number	Name	Description
1	ID	Communication line to the ID chip on an extension board
2	GND	Ground
3	ADC(+)	Analog-to-Digital Converter (ADC), alternatively positive part of differential ADC
4	ADC(-)	Analog-to-Digital Converter (ADC), alternatively negative part of differential ADC
5	GPIO1	General purpose I/O
6	GPIO2	General purpose I/O
7	PWM(+)	Pulse-Width Modulation (PWM), alternatively positive part of differential PWM
8	PWM(-)	Pulse-Width Modulation (PWM), alternatively negative part of differential PWM
9	IRQ/INT/GPIO	Interrupt request line and general purpose I/O
10	SPI SS B/GPIO	SPI Client Select or general purpose I/O
11	I²C SDA	Data line for I²C interface. Always implemented, bus type
12	I²C SCL	Clock line for I²C interface. Always implemented, bus type
13	UART RX	Receiver line of target device UART
14	UART TX	Transmitter line of target device UART
15	SPI SS A/GPIO	SPI Client Select or general purpose I/O
16	SPI MOSI	Host Out Client In line of serial peripheral interface. Always implemented, bus type.
17	SPI MISO	Host In Client Out line of serial peripheral interface. Always implemented, bus type.
18	SPI SCK	Clock for serial peripheral interface. Always implemented, bus type.
19	GND	Ground
20	V_CC	Power for extension boards (3.3V)