Expansion Connectors

The ODROID-C4 provides 40-pin dual row expansion header “J2”.
The location and pinout of these connectors are illustrated below. (Board Revision 1.0 : 2020/01/29)
All signals on the expansion headers are 3.3V except for the analog input signal.

Default Pin State GPIO & Export No Net Name Pin Number Pin Number Net Name GPIO & Export No Default Pin State
- - 3.3V 1 2 5.0V - -
I(P/D) GPIOX.17 (#493) I2C0_SDA 3 4 5.0V - -
I(P/U) GPIOX.18 (#494) I2C0_SCL 5 6 GND - -
I(P/D) GPIOX.5 (#481) 7 8 TXD1 GPIOX.12 (#488) I(P/U)
- - GND 9 10 RXD1 GPIOX.13 (#489) I(P/U)
I(P/U) GPIOX.3 (#479) 11 12 PWM_E GPIOX.16 (#492) I(P/U)
I(P/U) GPIOX.4 (#480) 13 14 GND - -
I(P/U) GPIOX.7 (#483) PWM_F 15 16 GPIOX.0 (#476) I(P/U)
- - 3.3V 17 18 GPIOX.1 (#477) I(P/U)
I(P/U) GPIOX.8 (#484) SPI0_MOSI 19 20 GND - -
I(P/U) GPIOX.9 (#485) SPI0_MISO 21 22 GPIOX.2 (#478) I(P/U)
I(P/U) GPIOX.11 (#487) SPI0_SCLK 23 24 SPI0_CS0 GPIOX.10 (#486) I(P/U)
- - GND 25 26 SPI0_CS1 GPIOH.6 (#433) I(P/D)
I(P/U) GPIOA.14 (#474) I2C1_SDA 27 28 I2C1_SCL GPIOA.15 (#475) I(P/U)
I(P/U) GPIOX.14 (#490) 29 30 GND - -
I(P/U) GPIOX.15 (#491) 31 32 GPIOH.7 (#434) I(P/D)
I(P/U) GPIOX.6 (#482) PWM_A 33 34 GND - -
I(P/D) GPIOX.19 (#495) PWM_B 35 36 GPIOH.5 (#432) -
ADC.AIN2 37 38 REF 1.8V
- - GND 39 40 ADC.AIN0

GPIO Map for WiringPi Library

GPIO WiringPi Name Mode Initial Level Header Pin Header Pin Initial Level Mode Name WiringPi GPIO
3.3V 1 2 5v
493 8 I2C.SDA0 IN 1 3 4 5v
494 9 I2C.SCL0 IN 1 5 6 GND
481 7 GPIO.481 IN 1 7 8 1 IN TxD1 15 488
GND 9 10 1 IN TxR1 16 489
479 0 GPIO.479 IN 1 11 12 1 IN GPIO.492 1 492
480 2 GPIO.480 IN 1 13 14 GND
483 3 GPIO.483 IN 1 15 16 1 IN GPIO.476 4 476
3.3v 17 18 1 IN GPIO.477 5 477
484 12 SPIO_MOSI IN 1 19 20 GND
485 13 SPIO_MISO IN 1 21 22 1 IN GPIO.478 6 478
487 14 SPI_CLK IN 1 23 24 1 IN SPI_CE0 10 486
GND 25 26 1 IN GPIO.433 11 433
474 30 I2C.SDA1 IN 1 27 28 1 IN I2C_.SCL1 31 475
490 21 GPIO.490 IN 1 29 30 GND
491 22 GPIO.491 IN 1 31 32 0 IN GPIO.434 26 434
482 23 GPIO.482 IN 0 33 34 GND
495 24 GPIO.495 IN 0 35 36 1 OUT GPIO.432 27 432
25 AIN.2 37 38 1.8V 28
GND 39 40 AIN.0 29

Note that I2C-1(Pin 27/28) is shared with add-on board RTC chip PCF8563.
So the GPIO feature on Pin 27/28 is disabled by default until you change Device Tree file.

GPIO Name Alternative Mode V PU/PD PIN
- GND - - - - 1
506 GPIOAO.10 SPDIF Output OUT 0 P/U 2
- 5.0V - - - 3
505 GPIOAO.9 I2S MCLK OUT 0 P/U 4
503 GPIOAO.7 I2S LRCLK OUT 0 P/U 5
504 GPIOAO.8 I2S SCLK OUT 0 P/U 6
500 GPIOAO.4 I2S Data Output OUT 0 P/U 7