I think a good course of action might be to upload your efforts to a site like PCBway as a community project. That way anyone who wants to build their own and doesn’t have a printer and such can just order a kit with mostly everything they need on their own and the project would list the BOM for anything PCBway doesn’t include (like the BG95 board). It would be the best of both worlds - minimal work for you, maximum access to the community.
Of course, you mention not wanting to bother with anything beyond the dev/test phase, so if throwing it up on PCBway is out of scope for you, I’ll take up the mantle once you’ve done your part.
I have thrown together a basic cellular modem expansion card PCB design on github, but I am not a professional and I would like some review or feedback on the design before I proceed to making prototype boards.
This design is 15mm longer than the example expansion card PCB so it will protrude out of the expansion card slot, but should still be more compact than trying to rework cellular adapters on the market into USB C. I am also using IPEX-I connectors, so you are free to pair it with flat antennas for compactness or SMA adapters for the big boy antennas.
The board should be compatible with Quectel EG95 (LTE Cat 4) and EG91 (LTE Cat 1) modems, and also BG96 (Cat M, Cat NB1) for the people who work with IoT and things like that.
wow this is like the first real visual progress we’ve seen on this project other than the couple of out of the blue images josh has sent of a prototype
What sim card slot so you use? Are you sure the sim card doesn’t protrude from the slot on the left side? I feat that it might not fit into the expansion card that way.
When the sim card is locked into position, it sticks out of the slot by 1.25mm. The expansion card has a 2mm gap between PCB edge and case outer edge, so it should fit.
It should fully support GNSS including power for active antenna. although that would again make the module stick out a bit more.
It should be prepared for manufacture and assembly at JLCPCB, including component order codes. The manufacturing files can be generated using KiKit. I tried to use components available at JLCPCB. The only exception is the modem, which they do not have in stock and would probably have to be provided to them using the consign option (should be theoretically possible to have e.g. an Aliexpress seller send it directly to JLCPCB to avoid customs but have not looked into that in detail).
Just wanted to share a (hopefully) helpful note (after my many struggles with the ESP8266 on this same exact front): the EG95 modem can draw over 700mA during LTE transmission so you probably need a voltage regulator that delivers at least 0.8, ideally 1A. The Quectel modem also needs a minimum of 3.3V (range is 3.3 to 4.3V) so you need a regulator with a dropout at max current of basically 0 or a higher voltage output LDO. The AP2112K will likely have issues with both current delivery (its max is 600mA) and voltage stability (dropout of 0.4V at max load).
Quectel provides a hardware reference design pdf if you sign up on their site and they have all the ratings and such for reference.
They recommend a buck circuit for power delivery stability.
Yeah I’m also not satisfied with using an LDO, it was just the part included in Framework example card schematics. I’ve changed to a switching mode power supply IC and it should deliver ~3.8V, the typical input voltage stated in the EG95 datasheet.
If you check his post history, it doesn’t look like he ever posted an update. Also, “Last Post: Oct 25, 2023, Seen: Dec 12, 2023”. Looks like it’s been over a year since he last logged in. Profile - Tim_Taylor - Framework Community
I would guess it didn’t work out, for whatever reason.
This is cool, looks like there is progress on a bunch of fronts. I will be ordering a rev2 (with the pwrkey fix) as soon as the dang EG95’s are in stock (I ordered them). Looks like there is quite a delay on these currently. But I am still planning on making these available as soon as I can!
I’ve just received 2 EG95-EX from Quectel, will assemble to test next week.
Also playing around with the EG912U assembly that I have, seems like the only way for Windows to connect to internet through it is to treat it as a dial-up modem. It performs about as advertised, 10 Mbps down and 5 Mbps up. All I could say is usable in a pinch.
