# Expansion Interface

The HackRF One expansion interface consists of headers P9, P20, P22, and P28. These four headers are installed on the commercial HackRF One from Great Scott Gadgets.

## P9 Baseband

A direct analog interface to the high speed dual ADC and dual DAC.

Pin | Function
--- | ---
1 | GND
2 | GND
3 | GND
4 | RXBBQ-
5 | RXBBI-
6 | RXBBQ+
7 | RXBBI+
8 | GND
9 | GND
10 | TXBBI-
11 | TXBBQ+
12 | TXBBI+
13 | TXBBQ-
14 | GND
15 | GND
16 | GND

## P20 GPIO

Providing access to GPIO, ADC, RTC, and power.

Pin | Function
--- | ---
1 | VBAT
2 | RTC_ALARM
3 | VCC
4 | WAKEUP
5 | GPIO3_8
6 | GPIO3_0
7 | GPIO3_10
8 | GPIO3_11
9 | GPIO3_12
10 | GPIO3_13
11 | GPIO3_14
12 | GPIO3_15
13 | GND
14 | ADC0_6
15 | GND
16 | ADC0_2
17 | VBUSCTRL
18 | ADC0_5
19 | GND
20 | ADC0_0
21 | VBUS
22 | VIN

## P22 I2S

I2S, SPI, I2C, UART, GPIO, and clocks.

Pin | Function
--- | ---
1 | CLKOUT
2 | CLKIN
3 | RESET
4 | GND
5 | I2C1_SCL
6 | I2C1_SDA
7 | SPIFI_MISO
8 | SPIFI_SCK
9 | SPIFI_MOSI
10 | GND
11 | VCC
12 | I2S0_RX_SCK
13 | I2S_RX_SDA
14 | I2S0_RX_MCLK
15 | I2S0_RX_WS
16 | I2S0_TX_SCK
17 | I2S0_TX_MCLK
18 | GND
19 | U0_RXD
20 | U0_TXD
21 | P2_9
22 | P2_13
23 | P2_8
24 | SDA
25 | CLK6
26 | SCL

## P28 SD

SDIO, GPIO, clocks, and CPLD.

Pin | Function
--- | ---
1 | VCC
2 | GND
3 | SD_CD
4 | SD_DAT3
5 | SD_DAT2
6 | SD_DAT1
7 | SD_DAT0
8 | SD_VOLT0
9 | SD_CMD
10 | SD_POW
11 | SD_CLK
12 | GND
13 | GCK2
14 | GCK1
15 | B1AUX14 (trigger output)
16 | B1AUX13 (trigger input)
17 | CPLD_TCK
18 | BANK2F3M2
19 | CPLD_TDI
20 | BANK2F3M6
21 | BANK2F3M12
22 | BANK2F3M4

Additional unpopulated headers and test points are available for test and development, but they may be incompatible with some enclosure or expansion options.

Refer to the schematics and component documentation for more information.