General Category > LisaList2
RGBTOHDMI understands the Lisa video signal
bmwcyclist:
Alex, could you post pictures of your set up?
Sigma7, do you have some drawings, photos or schematic to point out where I would get the signal from?
sigma7:
--- Quote from: bmwcyclist on April 20, 2025, 12:44:15 pm ---Sigma7, do you have some drawings, photos or schematic to point out where I would get the signal from?
--- End quote ---
The Motherboard schematic shows the signals at the card edge connectors for the CPU board and the chassis.
Between those is a buffer chip (the only 74 part on the motherboard), which buffers the video dotstream, hsync and vsync.
I haven't connected to the signals myself, so I can't say if it makes a difference to get them from before or after the buffer... hopefully Alex knows.
AlexTheCat123:
I can provide some pictures if you want me to, but I don't think they're going to be very useful to you. I'm not connecting directly to the motherboard; I'm instead hooking to a header on my Lisa breakout board that lets me run the card cage outside the Lisa. So looking at my ribbon cable between the breakout and RGBtoHDMI probably isn't super helpful since you won't be doing it the same way.
I'm connected after the buffer, so that's probably what I would do to if I were you, just to be safe. You just need to pull VID, HSYNC, and VSYNC off that chip, and run them to the RGBtoHDMI. HSYNC and VSYNC connect to HS and VS on the RGBtoHDMI as you would expect, and I believe VID connects to grn2, although I can't validate this last one right now because my RGBtoHDMI is hooked to a Lisa that's in the middle of compiling some LOS code right now! I know it hooks to one of the grn pins though.
And oh yeah, don't forget ground as well!
Lisa2:
--- Quote from: bmwcyclist on April 20, 2025, 12:44:15 pm ---...do you have some drawings, photos or schematic to point out where I would get the signal from?
--- End quote ---
For the digital RBGtoHDMI interface cable, I brought out the TTL signals from the Lisa MB. U1 ( LS123) pin 6 (VID) to IBM CGA pin 4 ( Green ), U1 pin 3 (Vsync) to IBM CGA pin 9 ( Vsync ), U1 pin 8 (Hsync) to IBM CGA pin 8 ( Hsync) and ground. Works perfect!
Rick
bmwcyclist:
Fantastic thank you!
Looks like I have a digikey order in my future,
--- Quote from: Lisa2 on April 20, 2025, 11:36:13 pm ---
--- Quote from: bmwcyclist on April 20, 2025, 12:44:15 pm ---...do you have some drawings, photos or schematic to point out where I would get the signal from?
--- End quote ---
For the digital RBGtoHDMI interface cable, I brought out the TTL signals from the Lisa MB. U1 ( LS123) pin 6 (VID) to IBM CGA pin 4 ( Green ), U1 pin 3 (Vsync) to IBM CGA pin 9 ( Vsync ), U1 pin 8 (Hsync) to IBM CGA pin 8 ( Hsync) and ground. Works perfect!
Rick
--- End quote ---
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