Unknown LCD-Display

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi!

I've found a nice little LCD-Dispaly in an old glucose-meter, which I'd like to use which one of my projects.

The display is connected to the PCB by 6 wires. As there are no markings or numbers on the LCD, I don't know how these wires are connected. I figured it must use some kind of SPI or i2c protocol to communicate... So I tried to analyse the connections with my arduino using this simple sketch:

void setup()
{
  Serial.begin (15200);
}


void loop()
{
  Serial.println (analogRead(1));
}

And this was what I measured:

pin1: 1023 (obvioulsy VCC)
pin2: 0 (Ground)
pin3: continously 550
pin4: continously 330
pin5: continously 550
pin6: continously 120

I expected to find at least one pin, where the voltage would regularily alternate between 0 and 1023 (serial clock). But the voltages don't alternate at all... :o

Did I make a mistake somewhere or can someone think of another way to find out how to communicate with that display?

2

If those pins are digital pins, not analog, then using 'analogRead()' will not tell you very much. Have you tried reading them with a digital input pin? You may need to read all of them simultaneously, rather like a logic analyser.

3

Well, I found out, that most of these LCD controller-ics have a typical clock frequency of ~60MHz and as Arduino runs on 16MHz, I think it's to slow to analyse those pins...
I think I won't be able to use this LCD after all..

4

Shame it's too fast to the Arduino. But if you can find out any data on the display, even just a part number, maybe you can find a data sheet, and hence more info about the interface.

5

Well, I found out, that most of these LCD controller-ics have a typical clock frequency of ~60MHz

What's your source for that information?

--Phil.