1. CM4 socket: suitable for all variants of Compute Module 4
2. 40PIN GPIO header: for connecting sorts of HATs
3. RJ45 Gigabit Ethernet
   dual RJ45 Gigabit Ethernet, 10/100/1000M compatible
   ETHERNET 0: CM4 original ETH
   ETHERNET 1: USB extended ETH
4. USB 3.2 ports: 3x USB 3.2 Gen1, for connecting sorts of USB devices
5. HDMI connectors: 2x HDMI, supports 4K 30fps output
6. CAM: 2x MIPI CSI camera ports
7. DC power supply: 7~36V DC wide voltage range power input
8. Dual LED indicators
   red: Raspberry Pi power indicator
   green: Raspberry Pi operating status indicator
9. Micro SD card slot: for connecting a Micro SD card with pre-burnt image (Lite variant ONLY)
10. FAN header: for connecting cooling fan, allows speed adjustment and measurement
11. DISP0
    MIPI DSI display port
12. USB SLAVE port:for burning system image into Compute Module 4 eMMC variants
13. RTC battery holder: supports CR1220 button cell
14. RTC interruption configuration
    PI-RUN: CM4 will reboot on RTC interruption
    GN-EN: CM4 power-down on RTC interruption
    D4: D4 pin is triggered on RTC interruption
15. IO-VREF selection:set the CM4 IO logic level as 3.3V or 1.8V
16. FAN power supply selection:select 5V or 12V power to drive the fan
17. System function configuration
    BT_DIS: Bluetooth disabled, for CM4 with antenna variant ONLY
    WiFi_DIS: WiFi disabled, for CM4 with antenna variant ONLY
    WP_DIS: boot mode switch, ONLY be used when NOT booted from eMMC or SD card
18. RTC/FAN I2C bus selection
    SDA0/SCL0: I2C-10 is shared with CSI/DSI
    GPIO3/2: I2C-1 is shared with 40PIN header
19. RTL8153:USB Gigabit Ethernet chip
20. EMC2301:fan controller allows fan speed adjustment and measurement
21. VL805:USB 3.0 HUB

  Connection image and pinout: