Palm Pilot LCD screen pinout in progress

[pproc]

Well, a multimeter to check continuity told me which pins were ground. Since there was an EL backlight driver chip with identifiable part markings, the datasheet told me which pin was VDD and which pin was the backlight enable.

The digitizer pins were easily traceable to the touchscreen.

There were 4 pins going to adjacent 4 traces close to the lcd glass, so guessed (correctly) they were the databus.

There was some circuitry and a test pin on the PCB that showed a high voltage (> 15V) so I figured the LCD contrast voltage was being generated onboard. One of the interface pins affected the voltage - setting it to 0 made the voltage 15V and setting it to 3.3V made it around 19V. So I guessed it was PWM control for the contrast.

Then, used a PIC32MX breakout board and soldered gpio pins and started experimenting, using the olimex code as a starting template.

The display enable pin was easy enough to find, not even an lcd flash happening until a particular pin was logic high.

Setting individual bits on the data bus told me the high-low order.

That left the timing signals and some possibly unknown control voltages.

Experimenting, I got as far as a very dim and flickering screen with my text in the right place. Pretty much unusable - something incorrect with the timing signals and/or driving voltages and I shelved the project last year.

And I am not sure if I damaged the lcd during the process or if the lcd was defective to start with. The EL backlight driver doesn't seem to be generating the minimum 80V ac required voltage, i can only see about 40V at the output - this is on both the units I bought.