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< Rock3‎ | CM3
    ROCK 3 >  Compute Module 3 >  Raspberry Pi CM4 IO Board



Getting Started

What you need


  • Radxa CM3
  • Raspberry Pi CM4 IO board
  • One of the Storage media below:
    • microSD, larger than 8GB.
  • Power supply
    • The CM4 is powered by DC port and has a wide range of input voltage, 12V.
  • USB Keyboard and Mouse
    • With four USB-A connectors, CM4 IO can be equipped with a full sized keyboard and mouse.
  • Monitor and HDMI Cable
    • CM4 IO is equipped with a full sized HDMI connector. HDMI capable monitor is recommended.
    • HDMI EDID display data is used to determine the best display resolution. On monitors and TVs that support 1080p (or 4K) this resolution will be selected. If 1080p is not supported the next available resolution reported by EDID will be used. This selected mode will work with MOST but not all monitors/TVs.
  • USB Male A to Micro USB cable
    • If you want write image on CM4 IO from USB port, you need an USB Male A to Micro USB cable to connect CM4 IO and PC.


  • microSD Card Reader
    • For flashing the image into microSD Card
  • USB type A to type Micro USB
    • Write image on CM4 IO from USB port
  • USB to TTL serial cable
    • This is needed for serial console.
  • Ethernet cable
    • CM4 IO supports Internet access via WIFI or Ethernet.
    • An Ethernet cable is used to connect your CM4 IO to a local network and the Interne

Hardware Documentation

Radxa CM3 RPI CM4 IO Board Resource

General purpose input-output (GPIO) connector

CM4 IO has a 40-pin expansion header. Each pin is distinguished by color.

GPIO number Function4 Function3 Function2 Function1 Pin# Pin# Function1 Function2 Function3 Function4 GPIO number
+3.3V 1 2 +5.0V
14 SPI0_MOSI_M0 I2C2_SDA_M0 PWM2_M1 GPIO0_B6 3 4 +5.0V
13 SPI0_CLK_M0 I2C2_SCL_M0 PWM1_M1 GPIO0_B5 5 6 GND
125 I2S1_SDI3_M1 SDMMC2_PWREN_M0 GPIO3_D5 7 8 GPIO0_D1 UART2_TX_M0 25
GND 9 10 GPIO0_D0 UART2_RX_M0 24
23 UART0_CTSn PWM0_M1 GPIO0_C7 11 12 GPIO3_C7 I2S1_SCLK_TX_M1 119
15 PWM0_M0 GPIO0_B7 13 14 GND
19 PWM4 VOP_PWM_M0 GPIO0_C3 15 16 GPIO3_D4 I2S1_SDI2_M1 124
+3.3V 17 18 GPIO3_D3 I2S1_SDI1_M1 123
138 I2S2_SDI_M1 SPI3_MOSI_M0 I2C4_SDA_M0 GPIO4_B2 19 20 GND
136 SPI3_MISO_M0 I2S1_SDO1_M1 GPIO4_B0 21 22 GPIO3_C6 I2S1_MCLK_M1 118
139 I2S2_SDO_M1 SPI3_CLK_M0 I2C4_SCL_M0 GPIO4_B3 23 24 GPIO4_A6 I2S1_SCLK_RX_M1 SPI3_CS0_M0 134
140 I2C2_SDA_M1 GPIO4_B4 27 28 GPIO4_B5 I2S1_SDO3_M1 I2C2_SCL_M1 141
21 SPI0_MISO_M0 PWM6 GPIO0_C5 31 32 GPIO4_C0 PWM11_IR_M1 144
22 SPI0_CS0_M0 PWM7_IR GPIO0_C6 33 34 GND
120 I2S1_LRCK_TX_M1 GPIO3_D0 35 36 GPIO4_A7 I2S1_LRCK_RX_M1 SPI3_CS1_M0 135
18 PWM3_IR GPIO0_C2 37 38 GPIO3_D2 I2S1_SDI0_M1 122
GND 39 40 GPIO3_D1 I2S1_SDO0_M1 121

More details about 40-pin Header

  • Pins marked with color orange are designed for debug console.
  • SPI:X2,SPI0/SPI3
  • I2C:X2,I2C2/I2C4
  • I2S:X2, I2S1/I2S2

IO Voltage

RK3566 have three IO voltages, 1.8V/3.3V. For CM4 IO, the high level voltage of GPIO pin on 40-PIN HEADER is 3.3V.

| GPIO       | Voltage Level | Tolerance |
| ---------- | ------------- | --------- |
| SARADC_IN3    | 1.8V          | 1.98V     |

GPIO number

Rockchip RK3566 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

The GPIO number can be calculated as below, take GPIO4_D1 (PIN26 on 4-0PIN HEADER) as an example:

GPIO4_D1 = 4*32 + 3*8 + 1 = 153
(A=0, B=1, C=2, D=3)

To set GPIO4_D1 output

cd /sys/class/gpio
echo 153 > export
cd gpio153
echo out > direction
echo 1 > value     # output high
echo 0 > value     # output low

System images and usage

Get your favorite system images from Radxa CM3 RPI CM4 IO Downloads.

And check the features of Ubuntu or Debian.

Flash images

Radxa CM3 RPI CM4 IO board supports two boot methods including booting from eMMC and booting from MicroSD. Select one of the following methods.


Check ROCK 3 FAQs first, if it doesn't help, start a new post on the forum