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With three USB3.2 and two Gigabit Ethernet ports, for all Variants of CM4




Onboard Interfaces



CM4-DUAL-ETH-BASE is a base board that can be used with Raspberry Pi Compute Module 4, and supports 7~12V DC power supply, onboard three USB3.2, dual Gigabit Ethernet ports and it is suitable for scenarios that require multiple network ports, such as soft routing.

Precautions for use

1: Do not plug and unplug any device except USB and HDMI when powered on
2: Confirm the fan voltage before connecting, support 5V and 12V, connect 12V by default, please modify the resistance of FAN_VCC when switching
3: The Type C interface is only used as the USB SLAVE interface to burn the image, and cannot be used as a power supply.
4: In order to ensure the normal power supply of CM4, please do not connect other devices when using the Type C interface to burn the image.
5: When CM4 is in normal use, it needs to provide at least 12V 1.5A power supply. Otherwise, there may be problems such as automatic shutdown, frequency reduction and so on.
6: For Opwenwrt, see the instructions for use.
7: This expansion board does not support POE function.


Compute_Module 4
Compute Module 4 IO Board 5.png

What's on board


No. Component Description
1 CM4 socket Suitable for all variants of Compute Module 4
2 40PIN GPIO Connect HAT module
3 Gigabit Ethernet connector Dual RJ45 Gigabit Ethernet ports, support 10/100/1000M network access
ETHERNET 0: CM4 native network port
ETHERNET 1: USB extended network port
4 USB 3.2 3-way USB 3.2 Gen1 interface, support various USB device insertion
5 HDMI Dual HDMI ports, support dual 4K 30fps output
6 CAM Dual MIPI CSI camera interface
7 DC Power 7~36V DC wide voltage power supply
8 Dual LED Red light: Raspberry Pi power indicator
Green light: Raspberry Pi working status indicator
9 Micro SD Used to connect the Micro SD card with the system to start Compute Module 4 Lite
10 FAN Convenient access to cooling fans, support speed regulation and speed measurement
11 DISP0 MIPI DSI Display interface
12 USB SLAVE Compute Module 4 eMMC Version can burn the system image through this interface
13 RTC Battery connector Can be connected to CR1220 button battery
14 RTC Interrupt pin switching PI-RUN: RTC trigger interrupt CM4 restart
GN-EN: RTC trigger interrupt CM4 power off
D4: RTC trigger interrupt D4 pin
15 IO-VREF selection CM4 IO logic voltage switch 3.3V or 1.8V
16 FAN power supply options can choose 5V or 12V voltage to drive the fan
17 System function switch BT_DIS: Bluetooth disabled, only for CM4 version with antenna
WiFi_DIS: WiFi disabled, only for CM4 version with antenna
WP_DIS: Start mode switch, only For use without EMMC boot or SD boot
18 RTC/FAN I2C bus selection SDA0/SCL0: I2C-10 and CSI/DSI shared
GPIO3/2: I2C-1 and 40PIN shared
19 RTL8153 USB Gigabit LAN Chip
20 EMC2301 Fan controller, control fan speed, measure fan speed
21 VL805 USB 3.0 HUB


Do not plug or unplug any device while it is powered on

Writing Image


Fan voltage switching

As shown in the figure, the FAN voltage is switched according to the position of the resistor, and the default is 12V.

  • Note: Please connect the fan before turning on the power of the base board and then complete the test. Please do not connect the fan after the base board is powered on, because the fan control chip has been powered on, otherwise the chip will be burned!
  • Note: Before connecting, please confirm whether the rated voltage of the fan is consistent with the voltage actually connected to the fan.

Please note that DSI and CSI are prohibited when using RTC.
I2C-10 is used by default

RTC (PCF85063a) on i2c-10, address is 0x51 (7-bit address)
FAN ( EMC2301 ) on i2c-10, address is 0x2f (7-bit address)

If you need to add it to your program instead of the kernel, you can refer to the C and Python demo reference click here


sudo nano /boot/config.txt
 #Add the following lines at the end
 #Add # in front of dtparam=audio=on
 #Save and exit, restart
 sudo reboot

How to use Hwclock

Synchronize system clock to hardware clock

sudo hwclock -w

Synchronize hardware clock to system clock

sudo hwclock -s
 #The network or the NTP needs to be closed, otherwise it will be changed back.

Set the hardware clock time:

sudo hwclock --set --date="9/8/2021 16:45:05"

View hardware clock

sudo hwclock -r

Display version information

sudo hwclock --verbose


When powered on, the fan will spin for 1 second, then stop for 2 seconds, and then spin again, this is a normal phenomenon
There is no official configuration method for the fan currently , there is a third-party configuration method:
This method is published by a third party, and we are not responsible for any problems!

mkdir -p ~/src
 cd ~/src
 git clone
 cd cm4io-fan
 sudo chmod 777
 sudo ./
 #The following is a description of config.txt
 Name: cm4io-fan
 Info: Raspberry Pi Compute Module 4 IO Board fan controller
 Load: dtoverlay=cm4io-fan,<param>[=<val>]
 Params: minrpm RPM target for the fan when the SoC is below
                            mintemp (default 3500)
        maxrpm RPM target for the fan when the SoC is above
                            maxtemp (default 5500)
        midtemp Temperature (in millicelcius) at which the fan
                            begins to speed up (default 50000)
        midtemp_hyst Temperature delta (in millicelcius) below mintemp
                            at which the fan will drop to minrpm (default 2000)
        maxtemp Temperature (in millicelcius) at which the fan
                            will be held at maxrpm (default 70000)
        maxtemp_hyst Temperature delta (in millicelcius) below maxtemp
                            at which the fan begins to slow down (default 2000)

Or directly refer to the following:


The fan will start to accelerate when temperature is higher than 45 degrees Celsius, and will up to the highest speed when higher than 50 degrees Celsius.


CSI and DSI are disabled by default. When using the camera and DSI, it will occupy three I2C devices: I2C-10, I2C-11, and I2C-0.

  • Open a terminal and run the following commands:
 unzip -o -d ./CM4_dt_blob_Source
 sudo chmod 777 -R CM4_dt_blob_Source
 cd CM4_dt_blob_Source/
 #If you want to use both cameras and DSI0
 sudo  dtc -I dts -O dtb -o /boot/dt-blob.bin dt-blob-disp0-double_cam.dts
 #If you want to ue both cameras and DSI1
 sudo  dtc -I dts -O dtb -o /boot/dt-blob.bin dt-blob-disp1-double_cam.dts
 #When using any DSI interface, HDMI1 will have no image output, even if you do not connect the DSI screen, as long as you compile the corresponding file, then HDMI1 will not output
  #If you need to restore, please delete the corresponding dt-blob.bin: sudo rm -rf /boot/dt-blob.bin
  # After execution, turn off the power and restart the CM4

Recording test

And then connect the cameras and DSI display
1: Please power off the IO Board first before your connection.
2: Connect the power adapter after connecting the cameras and DSI display
3: Wait a few seconds before the screen boot up.
4: If the DSI LCD cannot display, please check if you have added /boot/dt-blob.bin. If there already has the dt-blob.bin, just try to reboot.
5: The camera needs to be enabled by raspi-config, enter sudo raspi-config on the terminal, choose Interfacing Options->Camera->Yes->Finish-Yes and reboot the system

Old Version (Buster)

  • Test the Cameras:

Test camera0:

sudo raspivid -t 0 -cs 0

Test camera1:

sudo raspivid -t 0 -cs 1

New Version (Bullseye)

If you are using the latest Raspberry Pi OS (Bullseye):

libcamera-hello -t 0

#The new system uses dual cameras
#Remove or comment out the line camera_auto_detect=1 in config.txt

#Add the following lines:

#Add the corresponding line according to the camera you use, where imx219 is the camera sensor model, and there are other sensors

#then restart

#Other part of the commands:
#Check if the camera is detected
libcamera-hello --list-cameras

#Open the corresponding camera
libcamera-hello --camera 1
libcamera-hello --camera 0

#Taking Pictures
libcamera-jpeg -o test.jpg
#You can add --camera to specify the camera

More instructions click me

  • HDMI1 is disabled if you use DSI interfaces for displaying, even if you just compile the corresponding files without connecting to the DSI screen, please note it
  • Any connection of two HDMI ports can output images, not limited to which HDMI port, if two HDMI screens are connected, only HDMI0 has image output
  • If you want to enable both HDMI, please delete the dt-blob.bin file with the following command:
sudo rm -rf /boot/dt-blob.bin
  • Then reboot

Reference Raspberry Pi Manual



Openwrt has high customization and scalable performance. Openwrt is becoming more and more popular at present. Compared with commonly used wireless routers, openwrt's modifiable firmware allows us to customize router functions according to our own needs, such as single-arm routing, automatic Define routing policies, qos, intranet penetration, etc. Note: We do not provide any technical support for Openwrt system if there has any problem during use, only provide he following tutorials and images, and no other technical support other than hardware is provided.


The openwrt image configured above supports CM4 onboard wifi and the driver of RTL8153. CM4 can be turned into a smart router,
The following will tell you how to install Openwrt on the Raspberry Pi to realize the function of a wireless router, so that the devices in the LAN can access the Internet through the wireless router, and realize the intelligent management of the LAN. The overall network topology is as follows
After booting correctly, log in to the system:
The computer is connected to the ETH0 interface, and then directly ssh remote login or web page login
The configured system default IP is:
The default IP of the system without configuration is:
Account: root without password

If you think the network port is not enough, you can buy it USB 3.2 Gen1 TO Gigabit ETH RTL8153 expansion network port, if there is one ETH/USB HUB HAT RTL8152 can also expand the 100M Ethernet port and support it.

a) Check whether dtparam -audio -on is blocked in /boot/config.txt

b) Check whether the /boot/dt-blob.bin file exists, if it cannot be used, please delete it;

If you require technical support, please go to the Support page and open a tickets.