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Freigegebene technische Dokumentation veröffentlicht; Text-only und noindex

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'''Documentation notice:''' This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

== Summary ==
The official Raspberry Pi CM4 IO Board serves as a baseboard for the Compute Module 4. It consolidates interfaces on one side and is suitable both for development environments and for integration into end products via HATs and PCIe modules.

== Related products at JW Tech ==
* [https://shop.jw-tech.eu/p/WSAL18781 WSAL18781 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18782 WSAL18782 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18784 WSAL18784 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18785 WSAL18785 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18786 WSAL18786 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18787 WSAL18787 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18788 WSAL18788 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18789 WSAL18789 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18790 WSAL18790 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18792 WSAL18792 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18794 WSAL18794 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18795 WSAL18795 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL18796 WSAL18796 – Raspberry Pi Compute Module 4 IO Board, a Development Platform for CM4]
* [https://shop.jw-tech.eu/p/WSAL18806 WSAL18806 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL19180 WSAL19180 – Raspberry Pi Compute Module 4 Dev Kit, with Official IO Board and Optional 7" Touchscreen]
* [https://shop.jw-tech.eu/p/WSAL19181 WSAL19181 – Raspberry Pi Compute Module 4 Dev Kit, with Official IO Board and Optional 7" Touchscreen]
* [https://shop.jw-tech.eu/p/WSAL19754 WSAL19754 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL20390 WSAL20390 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL23619 WSAL23619 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL25531 WSAL25531 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]
* [https://shop.jw-tech.eu/p/WSAL25782 WSAL25782 – Raspberry Pi Compute Module 4, Options For RAM / EMMC/ Wireless]

== Technical overview ==
* Official Raspberry Pi baseboard, compatible with the Compute Module 4 (CM4).
* Interfaces are consolidated on one side; supports standard HATs and PCIe devices.
* PCIe Gen 2 x 1 port accepts standard PCIe cards; demonstrated working with NVMe drives via a passive adapter.
* PCIe interface does not support MSI-X; typical devices fall back to MSI.
* USB 2.0 is disabled by default (power saving); enabling requires adding dtoverlay=dwc2,dr_mode=host to config.txt.
* Newer OS images (after Oct 30, 2021) report 'config failed, hub doesn't have any ports! (err -19)' in OTG mode; fix by removing otg_mode=1 and adding the dwc2 overlay.
* RTC (PCF85063A) resides on I2C-10 at address 0x51; fan controller (EMC2301) at 0x2f on the same bus.
* Extended version only supports 12 V; the fan must be connected before powering on, otherwise the control chip may be damaged.
* DSI display: default resolution 800×480; when using the official board, jumper J6 must be closed.
* When using a DSI display, HDMI1 has no image output even if no DSI screen is connected; enabling two HDMI outputs requires removing the relevant configuration from config.txt.
* CSI cameras: single-port cameras work only on CAM0; CAM1 alone is not possible; dual cameras require both ports simultaneously.
* Older systems (Buster/Bullseye): CSI/DSI disabled by default; three I2C devices (I2C-10, I2C-11, I2C-0) are occupied; booting uses dtc compilation of dt-blob files.
* Newer systems (Bookworm): camera overlays such as ov9281, imx219, imx477, etc.; test commands libcamera-hello / libcamera-jpeg / libcamera-vid.
* All changes to config.txt require a reboot to take effect.

'''Commands and examples – verify before use:'''
<syntaxhighlight lang="text">
sudo nano /boot/config.txt
dtparam=i2c_vc=on
dtoverlay=i2c-rtc,pcf85063a,i2c_csi_dsi
#dtparam=audio=on
sudo reboot
sudo hwclock -w
sudo hwclock -s
sudo hwclock --set --date="9/8/2021 16:45:05"
sudo hwclock -r
sudo hwclock --verbose
uname -a
dtoverlay=i2c-fan,emc2301,i2c_csi_dsi,midtemp=45000,maxtemp=65000
i2cdetect -y 10
dtoverlay=vc4-kms-dsi-7inch,dsi0
dtoverlay=vc4-kms-dsi-7inch,dsi1
dtoverlay=ov9281,cam0
dtoverlay=imx219,cam0
libcamera-hello --list-cameras
libcamera-hello -t 0
libcamera-jpeg -o test.jpg
</syntaxhighlight>

== Notes and version constraints ==
* Fan connection only in powered-off state; connecting later may damage the control chip.
* RTC battery must be properly connected and voltage-intact, otherwise inaccurate time values.
* Camera CAM1 cannot be used alone; single-camera operation only via CAM0.
* Using DSI disables HDMI1; to enable dual HDMI outputs, remove the DSI configuration.
* Older kernel versions (< 6.1.31) do not support the EMC2301 fan driver.
* All configuration changes require a reboot; forgetting this causes features not to work.
* I2C address verification with i2cdetect -y 10; valid addresses show 'UU' instead of digits.
* Connecting devices while powered on is prohibited; always connect first, then power on.

== Source and revision record ==
* [https://www.waveshare.com/wiki/Compute-Module-4 Compute-Module-4 - Waveshare Wiki]
* Source revision: 103660
* Captured: 2026-09-01T03:38:51+00:00
* SHA-256: <code>35b65975beb83959b7e50227f13930b21eef00831b90d8170258fe6dc6794daf</code>

WSAL18781 – Compute-Module-4/en - Versionsgeschichte

JWTechPublisher: Freigegebene technische Dokumentation veröffentlicht; Text-only und noindex