Update: I got the 3.1 boards in, they look very good.
Happy to report that both the USB and I2S mux chips seem to work perfectly fine. Haven't yet tried sending I2S from the RP2040 to the CM4, will do that next.
The new horizontal buttons are nice and clicky, and the internal CM4-to-Vortex USB 2.0 connection is fully functional.
Will also work on getting a complete Pi image set up with all necessary software, ready to be flashed.

Found some mini-pcie graphics cards.

https://www.digikey.com/en/products/detail/ve … PEE-V5E/4895622

Duffman wrote on 2024-08-10, 05:45:

Found some mini-pcie graphics cards.

https://www.digikey.com/en/products/detail/ve … PEE-V5E/4895622

I don't understand why these graphics cards are so terribly expensive.

Eivind what's your recommendation on CM4 RAM/eMMC spec? Price difference is double between CM4 lite 1GB RAM/no eMMC and full tilt 4GB/32GB eMMC

vutt wrote on 2024-08-10, 09:21:

Eivind what's your recommendation on CM4 RAM/eMMC spec? Price difference is double between CM4 lite 1GB RAM/no eMMC and full tilt 4GB/32GB eMMC

I went with the lowest eMMC+wifi board myself. 1GB of RAM is plenty, and if I need more storage I can always set up a shared network storage drive from another computer. Nothing wrong with shelling out a bit more if you want larger on-board storage, though.
Note that you do need the eMMC variant (as is written on the PCB itself), since there isn't room to fit a microSD slot for the Pi. Also, you'd be crazy not to have wifi - would be a nightmare to interact with the Pi without it. 😀

Vridek wrote on 2024-08-10, 09:15:

Duffman wrote on 2024-08-10, 05:45:

Found some mini-pcie graphics cards.

https://www.digikey.com/en/products/detail/ve … PEE-V5E/4895622

I don't understand why these graphics cards are so terribly expensive.

Yeah, $260 is a bit on the expensive side for a SM750-based card. I think you should be able to get these for around $150 if you look around.
The reason they're so expensive is probably that they're made in quite small quantities and mainly sold as industrial equipment to companies to whom a couple of hundred bucks is a drop in the bucket. 😉

Note to myself - RTFM written on PCB 😀
Purist with FAT16 for DOS as I am 16GB with 7 partitions should be enough...

vutt wrote on 2024-08-10, 09:51:

Note to myself - RTFM written on PCB 😀
Purist with FAT16 for DOS as I am 16GB with 7 partitions should be enough...

We were talking about the CM4's storage, though? The TinyLlama itself has a MicroSD card slot you can populate with whatever size card you want - that's gonna be the main hard drive in DOS.

So operating system is running on TinyLlama SDCard and eMMC storage is used for whatever device CM4 is emulating. Ordered today 1GB RAM/8GB eMMC version.

What's your current estimate? When do you expect current HW iteration ready for us to use?

vutt wrote on 2024-08-10, 14:37:

So operating system is running on TinyLlama SDCard and eMMC storage is used for whatever device CM4 is emulating. Ordered today 1GB RAM/8GB eMMC version.

What's your current estimate? When do you expect current HW iteration ready for us to use?

Correct, the eMMC storage is primarily used for the Raspberry Pi's operating system, plus whatever else you want to serve to the TinyLlama over USB or serial.

Hardware revision 3.1 is done - as in, I've gotten a batch of boards that I'm currently testing. It all seems to work fine, so I guess I could put it up on github soon.
I definitely need to document a whole bunch of stuff, though. But yeah, in a few days maybe?
I already have 4 3 boards in hand and I suppose I'll order a few more if anyone's interested and don't want to do the whole PCB/assembly dance themselves. I'll get back to this later.

I found out that the JST SH ("qwiic") connector was wired up the wrong way (thanks, Ahmad!).
I'll make another revision of the board to fix this - will also try to get ethernet wired up between the SOM and CM4, though this isn't trivial as the signalling levels differ (1.8v vs 3.3v) and the PHYs might be picky about the diff pair impedance, common mode rejection, etc. We'll see if I can find room on the board for some magnetics (transformers) and extra caps and resistors...

Update: Just put in the order for a batch of revision 3.2 boards.
Changes from 3.1:
- Added an ethernet connection between the SOM and CM4.
- Added a third UART connection between the SOM and CM4 (mostly for control communication).
- Fixed the wiring issue with the JST connector.
- Improved shielding around the CM4's wifi antenna, to try to reduce noise when operating in 2.4 GHz (b/g) mode.
- Used the epoxy-filled/capped via option at JLC, to improve silkscreen asthetics (not visible in the renders below).

I'm working on an all-in-one program/script/service running on the CM4 that handles selecting/setting up floppy/cdrom images, synths, modem, etc - and can be controlled (over the new UART) from the SOM/DOS side using a utility program.

Amazing, well done. Cannot wait for it.

Amazing indeed. My CM4 arrived, so I have all the pieces now for final assembly.

A quick sneak peak at the control program I mentioned earlier:

I've been away since V2 but this looks like excellent development, very excited! Here's an ANSI graphic I put together for kind of a boot screen in DOS. I'd be happy to share it if you'd like to use it.

Just wondering, Eivind, have you ever looked into making Tiny Llama based on the som304rd52vine1 https://icop-shop.com/product/som304rd52vine1/?
som304rd52vine1 and cm4 will make the magic team. thoughts?

ahmadexp wrote on 2024-08-30, 03:33:

Just wondering, Eivind, have you ever looked into making Tiny Llama based on the som304rd52vine1 https://icop-shop.com/product/som304rd52vine1/?
som304rd52vine1 and cm4 will make the magic team. thoughts?

Now speaking for myself, apart from the price of the SOM which is really high this is a dead end, the IDE problem is really annoying.

Vridek wrote on 2024-08-30, 08:19:

ahmadexp wrote on 2024-08-30, 03:33:

Just wondering, Eivind, have you ever looked into making Tiny Llama based on the som304rd52vine1 https://icop-shop.com/product/som304rd52vine1/?
som304rd52vine1 and cm4 will make the magic team. thoughts?

Now speaking for myself, apart from the price of the SOM which is really high this is a dead end, the IDE problem is really annoying.

I won't be trying to make anything with those DX-based modules anytime soon. My main reason is that I can't run my custom Coreboot/SeaBIOS ROMs on them.
I'm still waiting to hear back from DMP about their upcoming EX3 SOM though... That will probably be a much better fit for me, fingers crossed.

Update: got the revision 3.2 boards in - and ethernet works! 😁
Still have lots of testing to do, but this is starting to look very good.

Pinging google from DOS (sorry for the lousy photo):