Quelltext der Seite WSAL19887 – CM4-IO-BASE-A/en

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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 CM4-IO-BASE-A is a composite breakout board by Waveshare for the Raspberry Pi Compute Module 4 (CM4/CM4L). It provides HDMI, USB, M.2, CSI camera and DSI display interfaces, a 40-pin GPIO header, a TF card slot (Lite variant only), and a PWM fan connector.

== Related products at JW Tech ==
* [https://shop.jw-tech.eu/p/WSAL19887 WSAL19887 – Mini Base Board (A) Designed for Raspberry Pi Compute Module 4]
* [https://shop.jw-tech.eu/p/WSAL20130 WSAL20130 – Mini-Computer Based on Raspberry Pi Compute Module 4 (NOT Included), Mini IO Board Lite Ver, Metal Case, with Cooling Fan]
* [https://shop.jw-tech.eu/p/WSAL20258 WSAL20258 – Mini-Computer Based on Raspberry Pi Compute Module 4 (NOT Included), Mini IO Board Lite Ver, Metal Case, with Cooling Fan]
* [https://shop.jw-tech.eu/p/WSAL20269 WSAL20269 – CM4-IO-BASE-A + USB HDMI Adapter, for Raspberry Pi Compute Module 4]
* [https://shop.jw-tech.eu/p/WSAL20271 WSAL20271 – CM4-IO-BASE-BOX-A + USB HDMI Adapter, for Raspberry Pi Compute Module 4]

== Technical overview ==
* V4 release notes: Fixed BT-DIS/WIFI-DIS silkscreen inconsistency; DSI interface changed from DSI0 to DSI1 with higher resolution support.
* Power: The Type-C port serves as a 5 V / 2.5 A power input and an eMMC programming interface. Do not connect other devices while flashing the image.
* HDMI: Two HDMI ports (HDMI0 and HDMI1), both supporting 4K@30 fps. Enabling a DSI display disables HDMI1 output.
* USB: Two USB 2.0 ports expanded to four via an FE1.1S hub chip. Disabled by default; enable with dtoverlay=dwc2,dr_mode=host in config.txt.
* M.2: M-Key connector supports PCIe devices such as NVMe SSDs, not SATA drives. Power limited to 1.5 A; version B recommended if throttling occurs.
* Fan: Only 5 V fans are supported; no speed controller is onboard. The PWM output connects to GPIO18 on the CM4.
* CSI cameras: Dual MIPI CSI camera connectors. Single-port cameras work only on CAM0; dual-camera setups require compiling a custom dt-blob.bin.
* DSI displays: From V4 onward, DSI1 is used. Older systems (Buster/Bullseye) need a compiled dt-blob.bin from the provided source archive.
* Boot selection: Jumper shorted boots from USB-C; jumper open boots from eMMC or TF card.
* No PoE support is available on this expansion board.

'''Commands and examples – verify before use:''' 
<syntaxhighlight lang="text">
dtoverlay=dwc2,dr_mode=host
libcamera-hello --list-cameras
libcamera-hello -t 0
libcamera-jpeg -o test.jpg
libcamera-vid -t 10000 -o test.h264
sudo nano /boot/firmware/config.txt
dtparam audio=on
sudo raspivid -t 0 -cs 0
sudo raspivid -t 0 -cs 1
wget https://files.waveshare.com/upload/7/75/CM4_dt_blob_Source.zip && unzip -o CM4_dt_blob_Source.zip -d ./CM4_dt_blob_Source && sudo chmod 777 -R CM4_dt_blob_Source && cd CM4_dt_blob_Source/
sudo dtc -I dts -O dtb -o /boot/dt-blob.bin dt-blob-disp1-double_cam.dts
</syntaxhighlight>

== Notes and version constraints ==
* If DSI is enabled, HDMI1 output is disabled even without a DSI screen connected; removing the DSI config and deleting /boot/dt-blob.bin restores HDMI1.
* M.2 power is capped at 1.5 A; sustained high draw may cause SSD throttling—consider version B for heavier loads.
* On older system versions (Buster/Bullseye), camera and DSI are disabled by default and require compiling a custom dt-blob.bin from the provided source archive.
* Single-port cameras only operate on CAM0; CAM1 cannot be used alone. Dual-camera configurations require configuring both ports.
* The fan has no speed controller, so fan speed cannot be dynamically adjusted; only 5 V fans are compatible.
* When flashing the image via USB-C, do not connect any other devices during the process to avoid failure.
* From V4 onward the DSI interface is DSI1; older firmware still uses DSI0, so configuration must match the hardware revision.

== Source and revision record ==
* [https://www.waveshare.com/wiki/CM4-IO-BASE-A CM4-IO-BASE-A - Waveshare Wiki]
* Source revision: 104442
* Captured: 2026-09-02T03:00:47+00:00
* SHA-256: <code>5fe1afe86441cade622b4e92cc82d01da2df8b99e37ffce23efe382d4a7ef0d8</code>