Datasheet
Table Of Contents
- Raspberry Pi Compute Module 4 IO Board
- Colophon
- Chapter 1. Introduction
- Chapter 2. Features
- 2.1. CM4 Module Connectors
- 2.2. PSU input
- 2.3. Dual Full size HDMI 2.0 connectors
- 2.4. Gigabit Ethernet RJ45
- 2.5. USB 2.0 Hub
- 2.6. Micro USB connector
- 2.7. Micro SD Card socket
- 2.8. PCIe Gen 2 x1 socket
- 2.9. Fan connector
- 2.10. Dual DSI display connectors ( 22pin 0.5mm pitch cable)
- 2.11. Dual CSI-2 display connectors ( 22pin 0.5mm pitch cable)
- 2.12. A Raspberry Pi HAT connector
- 2.13. Real Time Clock (RTC)
- 2.14. Jumpers
- 2.15. LEDs
- Chapter 3. Mechanical Diagram
- Chapter 4. Circuit Diagram
current limited switch.
2.4. Gigabit Ethernet RJ45
The Raspberry Pi Compute Module 4 IO Board uses a standard 1:1 Ethernet magjack, which supports POE as well.
Additional ESD protection is provided on the Raspberry Pi Compute Module 4 IO Board as it is typically needed in POE
applications. The POE signals from the RJ45 connector are connected to J5. Typically a POE hat will supply +5v to the
Raspberry Pi Compute Module 4 IO Board. As a typcially POE HAT doesn’t generate a +12v power rail PCIe expansion
cards the FAN will not function.
2.5. USB 2.0 Hub
The Raspberry Pi Compute Module 4 IO Board has an onboard USB 2.0 hub. This connects to the CM4 USB 2.0 port. Two
ports from the hub are connected to a connector. The two other ports are connected to a header, this header can be used
to provide two extra internal ports.
There is an internal current limit switch to provide VBUS to the USB connectors. The current limit is set to approximately
1.2A.
The USB interface is disabled to save power by default on the CM4 . To enable it you need to add the following to the
config.txt file :
dtoverlay=dwc2,dr_mode=host
2.6. Micro USB connector
The micro USB connector is designed to enable the CM4 to be updated via rpiboot. When a micro USB cable is plugged in
the USB hub is automatically disabled, so the CM4 USB 2.0 port becomes a USB device.
2.7. Micro SD Card socket
WARNING
For use only with CM4Lite modules
The micro SD Card socket is a PUSH-PUSH socket. To release the micro SD Card a gentle push on the micro SD Card will
enable it to be removed.
2.8. PCIe Gen 2 x1 socket
The PCIe socket is designed to take standard PC PCIe cards. You should ensure that there is a suitable OS driver for your
card.
The PCIe link on the Raspberry Pi 4, Model B is used for the USB 3.0 interface via the VLI805 XHCI controller. If the
application requires USB 3.0 interface then an external XHCI controller is required like the VLI805.
The PCIe link has been successfully used with an NVMe drive via a passive PCIe adaptor. Currently the CM4 bootloader
doesn’t support NVMe drives so you must boot via a different source.
If the application uses a standard PCIe card then it might be useful to have a small PCIe adapter to rotate the PCIe card
90degress to enable a more compact case.
Raspberry Pi Compute Module 4 IO Board
2.4. Gigabit Ethernet RJ45 5