I found a nice 2:1 or 1:2 mux/demux for the USB which can you definitely utilize.
TMUXHS221

you can have the VBUS of your USB connector going to the select of this chip making it so that when the USB connection is established with the PCB for flashing the CM4, your CM4 is connected as intended and when it is unplugged, USB goes to the Vortex native USB.

ahmadexp wrote on 2024-07-19, 05:08:

I found a nice 2:1 or 1:2 mux/demux for the USB which can you definitely utilize.
TMUXHS221

you can have the VBUS of your USB connector going to the select of this chip making it so that when the USB connection is established with the PCB for flashing the CM4, your CM4 is connected as intended and when it is unplugged, USB goes to the Vortex native USB.

Yep, that's interesting for sure - thank you! 😀 I'll take a closer look.

Speaking of using the CM4, something that might be doable using it and the picogus : I2S input into the CM4, with bluetooth audio output through it ?

Not sure how much of a rabbit hole that is, but could be interesting 😁

Deksor wrote on 2024-07-19, 16:55:

Speaking of using the CM4, something that might be doable using it and the picogus : I2S input into the CM4, with bluetooth audio output through it ?

Not sure how much of a rabbit hole that is, but could be interesting 😁

AFAIK, the CM4 only supports a single I2S connection, which I'm already using to output high-quality sound from munt, fluidsynth or an sc55 emulator.
Did you mean if it would be possible to repurpose this one, or did you hope another one existed?

I hoped another one existed, though if you use the raspberry pi as a bluetooth audio *output*, I guess its I2S output becomes useless and the midi synth audio can be redirected to BT and mixed with the picogus audio.
Maybe this could be done via a couple of jumpers ?
Either bluetooth audio mode, or analogue audio output ?

Deksor wrote on 2024-07-19, 18:21:

I hoped another one existed, though if you use the raspberry pi as a bluetooth audio *output*, I guess its I2S output becomes useless and the midi synth audio can be redirected to BT and mixed with the picogus audio.
Maybe this could be done via a couple of jumpers ?
Either bluetooth audio mode, or analogue audio output ?

I think this should be possible. I haven't (yet) tried, but I believe the Pi is capable of taking an I2S input signal and mixing it with ALSA. There isn't exactly a lot of spare room on the board, but I could probably make a 3x3 pin header fit somehow.
Another solution could be to look into whether the Pi is capable of bit-banging an I2S output signal...

Eivind wrote on 2024-07-19, 19:07:

Deksor wrote on 2024-07-19, 18:21:

I hoped another one existed, though if you use the raspberry pi as a bluetooth audio *output*, I guess its I2S output becomes useless and the midi synth audio can be redirected to BT and mixed with the picogus audio.
Maybe this could be done via a couple of jumpers ?
Either bluetooth audio mode, or analogue audio output ?

I think this should be possible. I haven't (yet) tried, but I believe the Pi is capable of taking an I2S input signal and mixing it with ALSA. There isn't exactly a lot of spare room on the board, but I could probably make a 3x3 pin header fit somehow.
Another solution could be to look into whether the Pi is capable of bit-banging an I2S output signal...

Actually I think bit-banging such a signal might not be feasible with a Pi. Thinking out loud, maybe a 4-channel bidirectional 2:1 mux/demuxer chip might do the trick. Could be controlled from the Pi as well.

It looks like dmp international online shop - shop.dmp.com.tw - does not exist any more. Getting 500 error.
Quick googling did not give me any separate SOM-128-EX sellers. One I found is 86duino bundle: https://icop-shop.com/product/86duino-one/
Eivind do you happen do know any alternative sources?

vutt wrote on 2024-07-21, 06:02:

It looks like dmp international online shop - shop.dmp.com.tw - does not exist any more. Getting 500 error.
Quick googling did not give me any separate SOM-128-EX sellers. One I found is 86duino bundle: https://icop-shop.com/product/86duino-one/
Eivind do you happen do know any alternative sources?

I'm hoping it's only a temporary glitch causing DMP's online store to give the 500 response. It's certainly more promising than if that address would have returned 404 at least...
AFAIK, ICOP is a subsidiary of DMP and you can buy all of their stuff from there, albeit at higher prices (industrial vs consumer). I see they're out of the SOM, you can try sending them an email asking if/when they'll restock? Both the "86Duino ONE" and "86Duino Zero" come with the SOM, so they can both be used. The Zero is a bit cheaper.

Yeah icop seems to be more like B2B site. Even shipping options are fast and even faster for cases like "my business process is down I need this overnight so $50+ USD delivery cost is peanuts".

Q: 86duino-one set does have optional accessory VGA board called MINIPCIE-9160-S for only +20 USD while MINIPCIE-9160 separately will cost $54. Do you know if "S" version limited somehow?

vutt wrote on 2024-07-21, 15:34:

Yeah icop seems to be more like B2B site. Even shipping options are fast and even faster for cases like "my business process is down I need this overnight so $50+ USD delivery cost is peanuts".

Q: 86duino-one set does have optional accessory VGA board called MINIPCIE-9160-S for only +20 USD while MINIPCIE-9160 separately will cost $54. Do you know if "S" version limited somehow?

I have no idea, sorry. Maybe they just use a different SKU for the VGA card that you can buy together with the ONE?

vutt wrote on 2024-07-21, 15:34:

Yeah icop seems to be more like B2B site. Even shipping options are fast and even faster for cases like "my business process is down I need this overnight so $50+ USD delivery cost is peanuts".

Q: 86duino-one set does have optional accessory VGA board called MINIPCIE-9160-S for only +20 USD while MINIPCIE-9160 separately will cost $54. Do you know if "S" version limited somehow?

Just in case, here is a compatible VGA miniPCIe card that used at works (on ebay): https://www.ebay.com/itm/355009190092?epid=13 … ABk9SR46fu5ibZA

ahmadexp wrote on 2024-07-22, 08:22:

vutt wrote on 2024-07-21, 15:34:

Yeah icop seems to be more like B2B site. Even shipping options are fast and even faster for cases like "my business process is down I need this overnight so $50+ USD delivery cost is peanuts".

Q: 86duino-one set does have optional accessory VGA board called MINIPCIE-9160-S for only +20 USD while MINIPCIE-9160 separately will cost $54. Do you know if "S" version limited somehow?

Just in case, here is a compatible VGA miniPCIe card that used at works (on ebay): https://www.ebay.com/itm/355009190092?epid=13 … ABk9SR46fu5ibZA

Ah, I remember someone mentioned that AST1300 chip a year or two ago! You've tested it and it works fine yeah?
I mostly use the "GD-SM750" card myself, with a VGA connector. I wish I had an HDMI variant though - do you have any recommendations for this, Ahmad? I know Innodisk makes one, but they're always so damned expensive... 😁

Edit: oh, and by the way - how does the HDMI card handle those retro resolutions? I mean, standard DOS is 720x400@70Hz - and many old games use 320x240 I think? Does it upscale everything perhaps?

Good news shop.dmp.com.tw is back online. Bad news for me they are asking 100USD shipping fee to deliver 2 items to my country.
I think I will go with icop shop then.

Been working on the next prototype, here are the changes so far:
- Hopefully better power and reset buttons.
- Ditched the "HID_POWER" jumper, programming the HIDman is most likely a one-time event, and back-powering the rest of the board doesn't really matter, especially if you haven't yet inserted the SOM or CM4.
- Ditched the Micro-B USB connector for programming the RP2040 / PicoGUS. Same reason as above, and can be done via the gamepad Type-A connector.
- Added a TMUXHS221 switch between the CM4 on one side and the "PI_USB_OTG" Micro-B connector and the SOM on the other. If power is present (cable connected) on the Micro-B port, USB traffic goes there, otherwise directly to the SOM (thanks, ahmadexp!).
- Because of this new onboard USB 2.0 connection between the CM4 and SOM, the Type-A USB connector to the SOM is now a single-port type instead of dual.
- Added a TMUX1574 switch between the CM4 on one side and the PicoGUS and a DAC on the other (for I2S signals). Which one is selected is set by a GPIO on the CM4. This means that we can either have the PicoGUS's audio sent to a DAC, for line out, or to the CM4 for Bluetooth audio output (thanks to Deksor for this one!). Both mixed together with MPU synth audio from the CM4 as before, of course.

A few updated renders; first the TMUXHS221 in place of the Micro-B connector:

The single-port native USB connector:

And the TMUX1574:

Eivind wrote on 2024-07-23, 08:20:

A few updated renders; first the TMUXHS221 in place of the Micro-B connector: […]
Show full quote

A few updated renders; first the TMUXHS221 in place of the Micro-B connector:

The attachment Screenshot 2024-07-23 at 09.55.50.png is no longer available

The single-port native USB connector:

The attachment Screenshot 2024-07-23 at 09.57.04.png is no longer available

And the TMUX1574:

The attachment Screenshot 2024-07-23 at 09.59.57.png is no longer available

this is beautiful! can't wait for you to demo it 😀

Looks fantastic indeed. I ordered DMP components today so waiting for TinyLlama final revision.

Q: What about v3 full power consumption? Do you expect to keep it under 2A with Vortex86VGA display module?

vutt wrote on 2024-07-23, 19:52:

Looks fantastic indeed. I ordered DMP components today so waiting for TinyLlama final revision.

Q: What about v3 full power consumption? Do you expect to keep it under 2A with Vortex86VGA display module?

That's an excellent question! I'll try to do a few measurements with a USB-C power meter dongle. Not sure if I have any Vortex86VGA cards lying around at the moment, but I don't think there's too much of a difference between that and the SM750-based ones.

Eivind wrote on 2024-07-23, 20:04:

vutt wrote on 2024-07-23, 19:52:

Looks fantastic indeed. I ordered DMP components today so waiting for TinyLlama final revision.

Q: What about v3 full power consumption? Do you expect to keep it under 2A with Vortex86VGA display module?

That's an excellent question! I'll try to do a few measurements with a USB-C power meter dongle. Not sure if I have any Vortex86VGA cards lying around at the moment, but I don't think there's too much of a difference between that and the SM750-based ones.

Ok, so here are some preliminary results:
Tried the system with the SOM at 500 MHz, running FastDoom playing MIDI music, and the CM4 having a dual-instance (for greater polyphony) sc-55 emulator (mk1) going: ~1.45 amps.
Putting the CM4 at its absolute maximum power draw running the cpuburn-a53 while playing Quake on the SOM: ~1.7 amps.
So - take these results with a handful of salt - I'm not sure about the accuracy of the USB-C power meter, but on the face of it it looks like a 2A power supply should suffice. I was using the 5A Raspberry Pi USB adapter, btw. And the GD-SM750 VGA card which I believe draws a bit more power than the Vortex86VGA.

Finally - it goes without saying that the USB ports on the TinyLlama are also able to output a fair amount of amperage if you connect something power hungry to them - I only had a simple keyboard attached.
If you plan on using something that draws quite a bit more, 2A might not be enough.