Can you snoop on an LCD screen.

Hi all,

Let me first say thank you for any help that anyone can give me.

Now to the point, I have a third party control board and the protocols are lock, I have no way of communication with this board by serial.

But I wondered is there any way that I can snoop on the LCD screen as this will be standard.
I am using an arduino meger

What I want to do is take whatever data is displayed on the screen and log it and use it to do calculations.

The logging and calculation I don’t think will be a problem but getting the data is a big one.

Please can anyone help?

How your third party control board"" been supply? is it 5V?
Show us some pictures.

The board is a 24v board, not sure on the screen yet.

I have attached a picture of the third party board. i need to find a way of geting the info that is on the creen off and onto my arduino meger.

That's going to be tough. You need some real test equipment, like an oscilloscope. Do you have one? Do you know how to use it?

A possible alternative might be to put a camera in front of the screen and have a computer like a Rasberry Pi or a PC read the numbers via character recognition.

I do have test equipment yes but I have to admit I am on a learning curve. I think a camera may not be reliable.

I really want some way of getting the screen data off.

The manufacture of the third party board has given me the manual for a communication board they make that allows there boards to talk to each other, but they are using their own protocols that I don’t have access to and converting circuit boards and well frankly they are polite and friendly but they don’t really want to help.

So after months of trying I thought I would ask the Arduino community.

Here is one of the App Note example on how to drive the LCD on that "third party board"

You can use an oscilloscope to see how the board had drive the LCD and the voltage, Arduino Mega can not take in negative voltage.

May be show us more photos of the board, front and back show that can help you better.

So there is a communication plug on the board? Then it is probably a reasonably simple serial data protocol. It would be easier to reverse-engineer that than the LCD.

The problem with the LCD is there's no data sent to the LCD: it's just a series of voltages that turn segments on and off. Determining which segments are currently on by snooping the pins is actually harder than it looks.

O so im kind of up a river with out a paddle then!

I wouldnt even know where to start with revers engineer the protocal. I have attached the PDF of the comunications board that was sent to me, the thing is that there coms board plugs on to 4 pins on the main board and there coms board has only two pins as an out put.

im well stuck :frowning:

BEBA bft coms board.pdf (714 KB)

OK a quick Google search indicates that the protocol might be encrypted. It does look like a large enough company that they probably already have a solution that they’ve sold to other customers before. I would try to ask them. If the project is worth money to you, then there must be a price that you can pay them. Your time as an engineer is a cost to your employer (or your business if self-employed) and saving that time by buying an off-the-shelf product is a simple economic decision.

I can’t imagine that what you are asking is an unusual request for that company. They must deal with customers every day who are doing something similar.