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Forum Index : Microcontroller and PC projects : PicoMiteHDMI framebuffer thoughts
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 6781 |
I'm guessing that the HSTX connections are like the HDMI "shoe", with 270R series resistors Peter? GP 12 D0+ 13 D0- 14 CK+ 15 CK- 16 D2+ 17 D2- 18 D1+ 19 D1- Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
But it can be made to work the same as RGB222 by setting the thresholds for the top 2 bits of R & G the same as B. (or by setting the thresholds for B the same as the top 2 bits of R & G may be better. ie. 3 bit without the LSB) For perfect shades of grey you set the LSB of R & G to 0 giving you in effect RGB222. Don't know how it would be implemented in DVI but if it were VGA it could be done with resistor values. On the PicoMiteVGA 4 bit greyscale and RGBI1111 are easy with plug-in modules. Edited 2024-08-17 08:32 by phil99 |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3150 |
I am deeply ignorant here; what kind of "plug-in modules"? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
This thread |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3150 |
Ah, memory. I see that I was the first to respond to your initial post in that thread. Thanks. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4223 |
Hi Phil, If you do as proposed, bright white is not white. You can restore that in the white balance of the screen, but then the greys are wrong again. Edited 2024-08-17 19:16 by Volhout PicomiteVGA PETSCII ROBOTS |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 9110 |
UPDATE  I've now been able to set the map tables to RGB555 so whatever colour depth of the framebuffer (2, 4, 16, or 256 colours) you will be able to map each colour to any of 32768 colours INCLUDING 32 perfect grey shades |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6781 |
Oh. wow.... :) Nice one! Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| bigfix Senior Member  Joined: 20/02/2014 Location: AustriaPosts: 128 |
Look at those boards - maybe some design inputs for Mick... RPi RP2350 Stamp Modules The carrier module has a micro HDMI connected to the HSTX port |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6781 |
I'm trying the PGA2350 at the moment. It's very compact but it seems to be working out well. I might try a slightly different arrangement for the Pico 2 because it's cheaper. I don't need all the IO at this stage. A bigger version would be nice in a CMM2 box, but that's something to consider later. The worst problem applies to all designs - the HDMI connection. There's only one common breakout board and it's big. There are several socket designs but all bad to solder. I've ordered a couple of both to have a look at before I commit to anything. I'd like to use a bare socket if possible, but I've never soldered anything with a 0.5mm contact pitch before! I did find a smaller breakout board but that was after I'd placed the order, of course. I think Adafruit or Pimorini do one too, but it was out of stock (of course). I've nothing to order from RS or Farnell so it's pointless paying their postage charges. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2350 |
hi Mick, how about these: https://www.ebay.com/itm/180653854018 and these: https://www.ebay.com/itm/174348749426 they look to be 3 rows of through-hole pins, on what is likely a 2mm pitch. btw, if looking at designing a board that takes the raw RP2350 chip, you might like to have a read of this thread discussing some 'design features' of the on-chip SMPS: https://www.eevblog.com/forum/projects/inductor-polarity/?all cheers, rob :-) |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9306 |
Nice find on the through-hole HDMI connectors, Rob!  I might get some of those, looking to the future, if I end up doing my own 2350 board(s). EDIT: @ Rob - that thread is a horror-story....   One would have hoped that the new chip could simply be powered by an EXTERNAL power-supply, and not be fixed to using what seems to be a temperamental on-chip SMPSU...   Edited 2024-08-18 16:32 by Grogster Smoke makes things work. When the smoke gets out, it stops! |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6781 |
I looked at the through-hole hdmi sockets yesterday and decided against them on a couple of grounds. The 3-row version would, I suspect, be very difficult to solder in the middle row. Unfortunately I couldn't find the pin numbering system so I don't know what it would affect. I suspect they are really intended for wave soldering. The 2-row version is better but IMHO has little to differentiate it from the SMD ones really. The pins are very close together and I don't fancy attempting to align the pins (even worse with the 3-row!). I did seriously consider this version though, it's the one I'd use if I decide the SMD is a non-runner. For the moment I think the modules are *a lot* easier, especially if mounted on two spacers and plugged into a socket. The series resistors could then go underneath the module, I think. That's something to try today. I'll leave the SMD system up to Peter, I think. :) All that work for a SMPS that I'm disabling on these designs in favour of a linear reg... :) Seriously, switching PSU layout has always been sensitive. There's nothing new here. Stray fields from the inductor are always there as there are high currents in the windings. The only difference now is that people try to squeeze the layout into smaller and smaller spaces so it's becoming more of a problem. Edited 2024-08-18 17:16 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1113 |
to be ready when my Pico 2 is available, I have just ordered some Adafruit 4984 DVI Breakout Board - Adapters with HDMI/DVI-connection.  https://botland.de/raspberry-pi-pico-hat-pin-expander/19784-dvi-breakout-board-adapter-mit-hdmi-dvi-anschluss-fur-raspberry-pi-pico-adafruit-4984-5904422347543.html The price of €2.90 is hardly more expensive than I have to pay for VGA sockets and i don't have to worry about complicated soldering Edited 2024-08-18 20:02 by Martin H. 'no comment |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2350 |
based on the attached datasheet of a similar connector (available from element14), it looks like the pin spacing is likely to be 1.50mm between each pin in a row, and 1.50mm between rows; of the 3 rows, the middle one offset by 0.75mm. 4161918.pdf this should be relatively easy to solder, although that Adafruit 4984 DVI Breakout Board posted by Martin looks good, especially since it also includes all the 220 ohm resistors. how obtainable are they at a reasonable shipping cost? cheers, rob :-) |
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| Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1113 |
looks like they are also sold at DigiKey NZ, so the shipping costs to NZ should be manageable Edited 2024-08-18 20:23 by Martin H. 'no comment |
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| Bleep Guru Joined: 09/01/2022 Location: United KingdomPosts: 509 |
That's the one I've ordered, for same reasons as you Martin :-) I think it's that one, or very similar, that Peter is also using for his development setup. Regards Kevin Edited 2024-08-18 20:49 by Bleep |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6781 |
That was the board that I looked at and was showing no stock. Pimorini - out of stock Pi Hut have 3 but their postage is 2.90 for a 1.90 unit Cool Component - sold out Proto-Pic - Add to wish list Postage prices from RS, Farnell, Mouser, Digikey etc. are stupid here unless you can make up minimum order charges. That's why I don't bother with the big suppliers unless I have no choice. Those were the connections that I'm designing around - the same as the "shoe" board for the Pico DVI output. Edited 2024-08-18 21:31 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 857 |
Oops I thought it was USB....my bad Edited 2024-08-18 21:33 by PhenixRising |
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| Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1113 |
the next question I have is whether this would not also work on a normal Pico 2040, maintaining the resolutions (same size of the screen memory) but determining the colors via user changeable color palettes 'no comment |
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