As I briefly mentioned yesterday, someone mentioned in this blog's comments a successful M.2 socket installation on the empty header on the Pi 500 (something I attempted, rather poorly!). With a few added components, and 3.3V supplied to a pad on the bottom via a bench power supply, the M.2 slot works just fine, allowing the use of NVMe SSDs or other PCIe devices.
Indeed, this person emailed me further proof, along with notes for anyone wishing to follow in their footsteps.
First, solder on four minuscule capacitors (rating may be gleaned off the CM5 IO Board schematics, I think?) on the PCIe lines heading to the NVMe slot. These are incredibly small, so a good microscope and decent SMD soldering skills are pretty necessary.
The M.2 socket is comparatively easy—though that didn't stop me from making a mess of mine, which did not look nearly as nice as the one above!
Then, using a bench power supply, apply +3.3V to the indicated pad in red, and ground to the pad in blue, and boot up the Pi 500.
If you don't see the device right away, you may need to enable the PCIe connection and set it to Gen 3 speed in your boot config.
Regarding the ICs required to get this working without a bench power supply:
Now I need to figure out which DC/DC converter they used on the backside of the PCB. It needs to be something with 3.3V and ENABLE functionality, because they need to disable power to ssd during Pi500 power down.
Maybe something could be gleaned from the CM5 IO Board Design Files? According to Bluesky user @eliasrm.bsky.social, it could be a AP3441SHE-7B. I also bought this M.2 socket, not sure on the other tiny components required but please feel free to post in the comments!
And the post from yesterday concluded with:
I intend to use it as a second linux PC, NVMe SSD is a must!
Indeed. I think for most of us, seeing the pads there, but unpopulated, was a giant head-scratcher. The Pi 500 would've been more of a slam-dunk win with the slot in place, even if empty.
Comments
I agree having an unpopulated m.2 would make the Pi500 that much more appealing. I understand the accessibility reasons for keeping the Pi’s on microSD, but giving this extra option to encourage people to “open up” their PCs seems like a no-brainer.
User @eliasrm.bsky.social posted about the regulator on Bluesky:
Digikey has the AP3441SHE-7B for $0.67, and I bought a single M.2 socket for about $1.60.
And @Mirko_DIY also guesses the rest of the circuits based on the CM5 IO Schematics.
Hallo,
have a look to the "Compute Module 5 IO Board datasheet" page 10 - D 2:
yours Chis
It was a stupid choice to leave it unpopulated. The HDMI converter I can live with but I see no use for a SD-only Pi500.
Might it be that adding those components makes the thing fail EMC, which could be why RPL haven't shipped it with the slot working as they wouldn't be legally allowed to sell it ?
It's possible. Though that wasn't the reason they stated when I asked about it in my initial testing and review.
Are you allowed to tell us the reason they quoted?
I'd assume the missing/inadequate 3.3V supply to be the reason
Is it possible that they left it unpopulated because they plan to have a more "premium" or "pro" version down the line with 16GB of ram? If so that seems a pretty poor excuse as 8GB is more than enough currently for a lightweight Linux system. Knowing that the lines are connected and working does make me more likely to buy this now though. Still don't like the keyboard though!
I feel like the Raspberry Pi foundation was kind of asking for the things people said about them in the comments section of the Raspberry Pi news forum, and it was kind of strange seeing an the spot for an M.2 slot but no slot and no provisions for it. If you're not interested in speeds, is it really worth switching to the Pi 500?
I worry unpopulating the M.2 socket is the first example of many in the profit-chasing downward spiral they might be falling into after the IPO.
I imagine, previously, there would be a post from them describing how they re-route the board 7th time and managed to save few cents somehow, how their CNC friend over somewhere managed to design a clever door for NVMe SSD, and have the socket from day one.
Personally, this is the first Pi I'm going to skip as I believe they will add the socket later (and in a more expensive version of 500, unfortunately).
While I appreciate the conciliatory tone of your blog posts, this is a much bigger deal imho. The fact that almost everything is on the board already, even leaving a dud connector and the M.2 mounting holes, reeks of the type of stuff a profits-hungry corporation would do, upselling you later on a "Pro" version that they produce at almost identical price.
Yes, I understand they are a business and they need to make money to survive, but come on.