Yes. Grab a programming board for your CM4. You benefit with faster read/write speeds, in exchange for the swapping feature of the device. The microSD slot is essentially hard-disabled.
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So the good option would be to buy a IO board for the CM4 I have now, install the OS to the inboard eMMC memory then just install the CM4 board on the uConsole?
- Question will I be able to use an additional SD card for more storage? or will that be disabled and not be able to be used as why you said its essentially hard-disabled?
Yes just install the CM4 in a io board and flash the emmc. The SD slot will be useless to you, but you do get the speed benefit of emmc.
Absolutely. The OS may even load faster. As Iāve said, the SD card slot in the mainboard is hard-disabled if you insert CM4 with onboard storage. Thatās a hardware limitation of the CM4. But if youāre adding storage through USB, that is very much possible.
As an additional note, the USB-C port does not accept hubs, but the USB-A port does. That doesnāt have video output support, if youāre thinking of plugging an external monitor to the USB-A.
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I made the same mistake - thought I could boot from the SD Card then write to the memory on the CM4. Just for your notes - I had trouble flashing to the CM4 when using the breakout board (I got the official RPI one) - not sure why - so I couldnāt write directly to the CM4 from my laptop. To work around that, I flashed a USB drive and booted the board to that (still using the breakout board) then used the rpi imager (running from the usb drive on the CM4) to install uConsoleās OS on the CM4 - worked like a champ.
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Another common problem, please donāt use CM4 with emmcļ¼ļ¼ļ¼
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For me the CM4 with EMMC worked just fine but you do need an IO board to flash it with the image. After youāve done that it will work perfectly, but it does add to the cost.
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So they were able to accept my return in pishop, I will be getting the Lite version.
- I will also be getting a different Wi-Fi antenna and other cool stuff with store credit.
I want to thank everyone that helped me and contributed to this issue. I should be getting everything tomorrow and testing it out with the new cm4 lite. Thank you again I greatly appreciate all the hep and guidance!
So itās booting up now, I did notice the trackball is only moving to the left and right and not up and down. Will mess around with it to see if thereās anything wrong with the contacts there.
The trackball is directional, there is a little silver nub on the circle on the bottom and it needs to point up or down.
Iām experiencing the same black screen issue and I also have bought the MMC version.
After reading this post I have purchased this IO board: https://amzn.eu/d/d722IHh
Can you please confirm me this is the correct board? Can you also point me to what should I do once I get this board?
I have read the whole thread but didnāt understand what should I do other than flashing the SD and trying to boot it with this board.
Thank you very much
I have Raspberry PIās original I/O board for the CM4 but it looks like this board will also work.
To flash the CM4 with the image I can recommend this guide: How to flash Raspberry Pi OS onto the Compute Module 4 eMMC with usbboot | Jeff Geerling
The most important thing is to reference the manual for your specific board in order to put your compute module in āUSB mass storageā mode. Once youāve done so the CM4 will show up on your computer as a USB storage device that you can then flash with the flashing software of your choosing (balenaEtcher/Raspberry Pi Imager).
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Thank you very much @Hendrikvanderplas for this guide! Will try as soon as my IO board arrives.
I successfully flashed the MMC with the IO board and was finally able to boot it up! Thank you very much for your input. Iām using the RexBookworm version.
One last think that i didnāt undestand is if will be able to use the my SD card once my OS has boot.
Once I plug it in, nothing happens: mount, dmesg and fdisk do not show anything and i canāt access my sd card.
SD card should work, right?
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Nice!
The SD card slot wonāt work with the MMC CM4 unfortunately.
damn! looks like I will still need a CM4 Lite then.
There is still one think I do not understand: if I mount my MMC CM4 on my IO board, will i be able to access the SD card? is this a limitation of CM4 or uConsole?
From the the relevant Respberry Pi forum topic: āNo, the SD card signals are connected to the EMMC and there is no software setting or hardware jumper which would allow the controller to use the SD slot instead.ā
So whenever you use the uConsole or the I/O board, you wonāt be able to use the SD card slot. You could however mount a USB-drive inside or outside the device to add storage.
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thank you! Iām really surprise of this design decision 
I agree, it would have been really nice to have the option to use the SD card slot. I imagine they had to compromise on the architecture to fit the eMMC memory.
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