Hooking up a 20-pin TFT LCD Screen?

Question

I have an 5" TFT LCD screen that I pulled out of an old portable TV/Monitor which has a ZIF connector and a 20 pin flat flex cable attached to it. At first I figured I could simply attach this to the display ZIF socket on my Raspberry Pi Model B (v1 rev 2.1), however it seems that the LCD's connector has 5 (?) more pins than the Raspberry Pi does. Unfortunately, I do not have a scope to inspect exactly what each of these lines do. Is it possible for me to figure out how to connect this directly to my Pi using the ZIF connector? The board for this device does have a 3.5mm jack for A/V input, should I simply wire the Pi's video output to the board's video input on the A/V input jack? It would be nice to not have to use the board because it contains a ton of extra components for picking up UHF/VHF frequencies and such. 
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shabaz · Accepted Answer

Hi Ryan, There is near to zero chance of this functioning via the flat flex unfortunately. You could use the 3.5mm socket as you say, provided it is intended for typical composite (often brought out on an RCA connector) use. However, this is an analog standard definition (SD) system, the image would be quite poor and no reasonable resolution for general use would be possible.

baldengineer · Answer

You still can't use the Pi's ZIF connector (directly). However, you could use the GPIO pins. But it isn't a trivial amount of work.

First, you need to determine the pin-out of the LCD panel. Not sure how you would go about reverse engineering it, so it'd be ideal if you could find some documentation on it.

Second, you'd need to build a breakout board to connect to the LCD's flat ribbon, to the Pi's GPIO. (This step is relatively straightforward.)

Third, configure the Pi's GPIO for LCD operation.

The good news? There was a Ben Heck Episode where he did something very similar. He was trying to make a portable retropie/mame device. In this case, he was directly driving the LCD, similar to what you are trying to accomplish.

Episode 322: Rasp Pi No HDMI - Portable MAME Part 1