Problem with 27979 LCD display

Pyrotom

Way back when I first bought a Parallax product (a Javelin chip) I also bought a 27979 4x20 Serial LCD. I never got it to work with the Javelin, but just assumed it was me screwing something up. Recently while cleaning up mu shop I came across it and decided to try it with the Propeller. Same results

If I set the DIP switches to test and apply power, it shows the proper test message. Then I set the DIP switches for any other setting and try to drive it with FullDuplexSerial and get nada. Zip. Nothing but the cursor sitting there staring at me. I'm a lot more confident of what I'm doing with the Prop, and I'm sure the baud rates are right. I've tried it driving directly from a Prop pin and buffered through a 74LS04 chip to get a 5v drive signal.

Am I doing something obviously wrong, or do I just have a defective display??

CON
        _clkmode        = xtal1 + pll16x
        _xinfreq        = 5_000_000
obj
   term: "tv_text"
   panel: "FullDuplexSerial"
var
   
pub go | x
   start
     
pub start | r, sta, bytes, cts, sec
   term.start(16)
   term.str(string("Starting display test "))
   panel.start(10,9,0,2400)
   waitcnt(80_000_000+cnt)
   panel.tx(25)
   repeat
    panel.str(string("Hello, world"))

sylvie369

I just set one up on a Propeller last night, so the memory is fairly fresh. I didn't use any external chips, but rather connected a 5v power supply, set it up with a common ground with the Propeller, and put a 1K resistor in series to the Propeller I/O pin. That all works fine.

For software I'm using the Debug LCD object. Try that - it should make life much easier.

If you want to use FullDuplexSerial, you might start by looking at whether or not the "start" method (panel.start in your code) is returning "true" when you use it:

PUB start(rxpin, txpin, mode, baudrate) : okay

'' Start serial driver - starts a cog
'' returns false if no cog available

I see you're connected to another monitor, so it should be easy to indicate this.

Post Edited (sylvie369) : 11/11/2008 11:12:02 AM GMT

hal2000

Try this subject
I think it's easier

http://obex.parallax.com/objects/40/

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