CM3+ w/ eMMC (non-Lite)?

[ProgramMax]

I assembled my Freeplay CM3 but couldn't get it to boot. I followed all the instructions I could find, making sure I didn't miss anything. I then checked the forums. After a bit of hunting, I happened upon "You must use the CM3 (+) Lite. You cannot use a CM3 module with eMMC."

I only have the CM3+ w/ eMMC.

I'm looking for a CM3+ Lite now to get this working. But in the mean time, I wonder:
1.) Perhaps this should be more clear on the web page? It says it can be purchased with a CM3+ Lite or you can provide your own. But it doesn't mention that non-Lite won't work.
2.) Why do the non-Lite versions not work? Do they boot from eMMC instead of the SD card with no option to reconfigure that? If so, perhaps there is a roundabout way to install onto the eMMC?

Thanks!

[Flavor]

Hey ProgramMax.

You are right that it states in multiple places that you need to supply your own Raspberry Pi CM3 Lite or CM3+ Lite, but it doesn't explicitly state that it will NOT work with other Raspberry Pi.

I will add something to that effect to hopefully make it even more clear for future customers.

For your question 2: Internally, the Compute Module uses the same lines for eMMC as it would for the SD card.

It's POSSIBLE (but not recommended) to modify the 0402 resistors on a CM3 to bypass the built-in eMMC. This involves moving multiple tiny (0402 is 0.04” x 0.02”) resistors from one position to another and bridging 5 other pads. Once done, it's effectively a Lite.

As far as installing to eMMC and booting from that, I will test it ASAP.

[Flavor]

I just tried it with a 16Gb eMMC CM3+.  It's working!

On my Mac, I basically followed https://github.com/raspberrypi/usbboot using a RPi CM3+ Development Kit.  You plug the CM3+ into the DevKit and then plug in USB to your computer.

Code:

git clone --depth=1 https://github.com/raspberrypi/usbboot
cd usbboot
brew install libusb
make
sudo ./rpiboot

After that, you can use the attached CM3 as if it were a SD card, and you can burn a SD image to it.  The process is a lot slower than burning to an SD.

I used the "Freeplay_CM3-and-Zero2_Test_21110201.img.gz" from https://drive.google.com/drive/folders/0...dwp_RqwzsQ and used the Raspberry Pi Imager to burn that file to the CM3+.

If you use a CM3/CM3+ with eMMC, then the SD slot on the Freeplay CM3 is totally useless.  The lines from the SD card will not even connect to the Pi's processor.  You can have an SD in or out, but the Pi will never see it.  The eMMC takes the place of the SD card.

P.S.  The development kit I used is just like this one.  https://www.ebay.com/itm/224775123233  Note that a normal kit from a shop would include actual Compute Module 3, but that eBay listing does not include any actual CM3.

[ProgramMax]

That's great to hear! Thank you!

I do not have a dev kit like that, but I will grab one.

[ProgramMax]

I ordered a CM3 Dev Kit, which arrived today.
I wanted to follow up and confirm this solved the problem for me.
Thanks again!

[Flavor]

That's awesome news, ProgramMax! I hope this helps anyone else that comes along. I might consider how we can mention this on our page while also making it clear that it's intended for the LITE even though a eMMC model can be made to work.