Reverse Engineering A Segmented LCD Display

[Himszy]

Hi,

I have here a golf Laser Rangefinder module that prints the distance readout to a LCD display. I've taken the unit apart and managed to gain access to the inputs to the display (after the LCD driver). In an attempt to convert my LCD readout -> RS232 one I plan to stick a logic analyser on the line and calculate how it works.

Is this the best way?

What sort of voltages should I expect considering the unit is powered from 3V? I'm assuming (perhaps incorrectly?) that the unit doesn't have an inverter and so can be read with a typical LA.

I don't have a scope unfortunately to read the voltages.

Cheers,

 

[DirtyLude]

You mean you're trying to figure out what's going directly into the LCD, after the driver? Static LCD displays aren't complicated. They take AC power, so the power directly to the LCD is going to be swapped back and forth between power and ground, so if your logic analyzer can't take negative voltages don't bother. Even then, you don't need a logic analyzer for this. There's no 'logic' here. Except for the AC, it works like a LED display with a common ground.

Here's a basic tutorial on driving static LCD displays.
**broken link removed**