Rockpi4/hardware/gpio

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    ROCK Pi 4 >  Hardware >  GPIO

General purpose input-output (GPIO) connector

ROCK Pi 4 has a 40-pin expansion header. Each pin is distinguished by color.

GPIO number	Function2	Function1	GPIO	Pin#		Pin#	GPIO	Function1	Function2	GPIO number
		+3.3V		1		2		+5.0V
71		I2C7_SDA	GPIO2_A7	3		4		+5.0V
72		I2C7_SCL	GPIO2_B0	5		6		GND
75		SPI2_CLK	GPIO2_B3	7		8	GPIO4_C4	UART2_TXD		148
		GND		9		10	GPIO4_C3	UART2_RXD		147
146		PWM0	GPIO4_C2	11		12	GPIO4_A3	I2S1_SCLK		131
150		PWM1	GPIO4_C6	13		14		GND
149		SPDIF_TX	GPIO4_C5	15		16	GPIO4_D2			154
		+3.3V		17		18	GPIO4_D4			156
40	UART4_TXD	SPI1_TXD	GPIO1_B0	19		20		GND
39	UART4_RXD	SPI1_RXD	GPIO1_A7	21		22	GPIO4_D5			157
41		SPI1_CLK	GPIO1_B1	23		24	GPIO1_B2	SPI1_CSn		42
		GND		25		26		ADC_IN0
64		I2C2_SDA	GPIO2_A0	27		28	GPIO2_A1	I2C2_CLK		65
74	I2C6_SCL	SPI2_TXD	GPIO2_B2	29		30		GND
73	I2C6_SDA	SPI2_RXD	GPIO2_B1	31		32	GPIO3_C0	SPDIF_TX	UART3_CTSn	112
76		SPI2_CSn	GPIO2_B4	33		34		GND
133		I2S1_LRCK_TX	GPIO4_A5	35		36	GPIO4_A4	I2S1_LRCK_RX		132
158			GPIO4_D6	37		38	GPIO4_A6	I2S1_SDI		134
		GND		39		40	GPIO4_A7	I2S1_SDO		135

More details about 40-pin Header

• Function marked with color orange is the default function of this pin.
• Except Pins for power supply, all pins are laid out directly to Soc RK3399.
• For pin 3, 5, 27, 28, 29 and 31, each pin is connected to the 3.0V supply through a 4.7K pull-up resistor.
• Pin 19, 21, 23, 24 are laid out directly to the pins of SPI device on board.
• Pin 7 is laid out directly to the pin of MIPI CSI on board.
• UART
  • UART2 is enabled as U-boot and Linux serial console by default. Check Rockpi4/dev/serial-console to use. Check Rockpi4/hardware/devtree_overlays to disable serial console on UART2.
  • UART2 & UART4 support a wide range of baud rate. It includes but not is not limited to the following baud rates. For instance, 115200bps. 500000bps, 1500000bps and so on.
  • For v1.4 and later hardware, on board SPI flash is soldered, UART4 PINs are used as SPI function.
• For I2C-2 and I2C-7
  • We have do the test using the i2c device e2prom. We need to open the i2c device file, and then do the read or write operation.

IO Voltage

RK3399 have three IO voltages, 1.8V/3.0V/3.3V. For ROCK Pi 4, below is the default voltage:

| GPIO       | Voltage Level | Tolerance |
| ---------- | ------------- | --------- |
| GPIO3_C0   | 3.3V          | 3.465V    |
| ADC_IN0    | 1.8V          | 1.98V     |
| Other GPIO | 3.0V          | 3.14V     |

GPIO number

Rockchip RK3399 GPIO has 5 banks, GPIO0 to GPIO4, each bank has 32pins, naming as below:

   GPIO0_A0 ~ A7 
   GPIO0_B0 ~ B7
   GPIO0_C0 ~ C7
   GPIO0_D0 ~ D7
   
   GPIO1_A0 ~ A7
   ....
   GPIO1_D0 ~ D7

For Rockchip 4.4 kernel, the GPIO number can be calculated as below, take GPIO4_D5 (PIN22 on 40PIN GPIO) as an example:

   GPIO4_D5 = 4*32 + 3*8 + 5 = 157
   (A=0, B=1, C=2, D=3)

To set GPIO4_D5 output

   cd /sys/class/gpio
   echo 157 > export
   cd gpio157
   echo out > direction
   echo 1 > value     # output high
   echo 0 > value     # output low