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Reverse Engineering LCD Controller

A project log for The ZStation: an 8 bit game console

This little project is part of a series of consoles im making

floppidydingoFloppidyDingo 04/01/2016 at 02:040 Comments

A game console is nothing without some form of output, and LCD displays are expensive for the size I want. Lucky for me, a friend of mine gave me an old printer to tear apart, and now I have an LCD that very conveniently has an LCD controller board already made for me. Bad news is, there are no schematics for me to lookup, so I'm basically working with a black box. But this didn't stop me!

It was time to bring out my trusty multimeter and datasheets for the LCD (A025CN03) and it's controller (UGP051). Using those three things, I started probing around to find out what pin on the connector did and how I'm supposed to wire it. After some experimenting, I have came up with this possible pinout:

LED+
LED-
LED-
Control for negative voltage (?)
+15V
GND
DCLK
GND
HSync
VSync
GND
D7
D6
D5
D4
GND
D3
D2
D1
D0
GND
VCC
VG resistor
VG

There are two pins I'm still figuring out. First is the control for the negative supply. I'm not sure if it's PWM, a digital enable signal, or an analog signal. If it's PWM, there is not feedback provided that allows me to adjust the frequency, so I think I can safely omit that possibility. Next is the VG pin. In one of the datasheets, there is a sample circuit that leaves this pin connected to ground through a capacitor. This is implemented on the board, so I think I can safely ignore that pin as well.

Once I get the signals figured out, then it's time to start coding. I have an ATMEGA328 to prototype with, then once I have a good signal, I'll port the code to work with the ATMEGA1284.


I tested my negative control signal, and no dice. I'm better off pulling out the IC and making my own controller board based off the sample circuit.


I done goofed. As I was trying to pull the IC off of the board, the tip to my soldering iron snapped in half. I tried to work with the short stub I was left with, and instead I wrecked the IC. Oops. It's a good thing I can get the exact same IC from Newegg. I'll just buy it from there and say I removed it successfully. Shhhh, nobody will ever know.

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