LK204-25 Module and DSP precessor

[Juan]

Hi, I am trying to interface the LK204-25 LCD module with a DSP processor through the serial (RS232) port. Is there any reason why this cannot be done...I mean is the LCD interfaceable with a Digital Signal Processor, which has a serial communications port?

These are thetwo commands I am sending to the LCD to start with:
*UATX = (0xFE); // these two command will clear the screen.
*UATX = ('X');

Am I missing something here? should I do some kind of initialization first to the LCD?
Thanks

[Paradigm]

As long as the DSP's serial port follows the RS232 specification, it should be ok. I would connect the LCD to a PC and test it first. Most units don't require any initialization. After that, about the only two things it could be are:

- Reversed RX/TX lines. Make sure the TX from the DSP goes to the RX of the LCD and vicee versa.
- Improper software setup of the embedded processor. Make sure you have the right speed and have it set to 8 data bits, no parity, and 1 stop bit.

If you have access to a scope, probe out the RX/TX lines. Assuming that you're talking TTL levels directly to it, you should see data going from 0 - 5V, and the interval should be at the right frequency.

If you provide a little more detail I might be able help some more. Things I would need to know are:

- Which LCD unit are you using
- How you are connecting it to the DSP (via 232 drivers or directly at TTL levels)
- Which DSP are you using
- What speeds are you trying to communicate at

Let us know if you need anything else.

[Juan]

James McTavish thanks for your repply. I had the TX/RX lines going from the processor to the LCD reversed.

Thanks

[Miles]

I feel your pain...if I had a quarter for everytime I had the Rx/Tx lines reversed, I'd be rich!!!