Serial LCD's

I'm have inconsistant results when using a Serial LCD as a debug/development tool to tell me what's happening in my program.

I've homed in on:

+ Pausing for 1 second on powerup to all the LCD to stabalize
+ I pause for 0.5 seconds after a clear
+ If I direct the cursor to the home position (line1 or line2) I'll pause for
10ms or so to make sure the command is executed.
+I tried running at 2400 baud and have changed over to 1200 baud.

One frequent quirk is that I usually get a bogus character at the home postion
after powering up, clearing and sending the first "Message".

Seems I'm spending more time debugging the LCD display rather my code. :-(

Thanks for any experience you can share...Chris

did you try to add
DEFINE CHAR_PACING 1000

at the program header to see what's happening

Thanks Steve,

I've tried pacing after I posted my question. It has made a difference but I still get a garbled character on the very first access to the LCD. The code currently is:

DEFINE CHAR_PACING 500
..
Pause 1000
Serout 3,N1200,[254.1]
Pause 500
Serout 3,N1200,[254,20]
Pause 20
Serout 3,N1200,["Waiting For Cmd"]
Serout 3,N1200,[254,192,"Address = ",#UnitAddr]

The VERY FIRST time this code is executed, I will get a garbled character in front of the message "Waiting for Cmd". Can't for the life of me figure out what's causing it.

Not a big deal for what I'm doing but I would like to understand what is happening here.

Thanks..chris

Hello Chris,

Chris>>The VERY FIRST time this code is executed, I will get a garbled character in front of the message "Waiting for Cmd". Can't for the life of me figure out what's causing it.<<

Try sending two "Clear" statements in a row.

First guess is, the senquencing of the Serial data between the two systems. Bad grounds will cause this.

Dwayne

That seemed to do the trick. I did however have to put in a 100ms pause between the clears.

Thanks...chris

Quote:

---

Pause 1000
Serout 3,N1200,[254.1]
Pause 500
Serout 3,N1200,[254,20]

---

hope this is not an error from you guy 254.1 or 254,1?

can you try
SEROUT 3,N1200[254,1,254,20,"first message",13,10]

what about now?!?

Hi Chris,

My guess is that your seroutpin is floating up to the point when you send the first character, this character will for this reason be garbled. You could either put a "LOW 3" before the first pause(1000), or you could add a pulldown resistor to the serial datapin. 10k would probably be enough.

/Ingvar

I'll give this a try a little later on this morning. I have a scope so I'll attempt to see what's happening.

Thanks for the tip..

Chris

Hi Ingvar,

The resistor did the trick. I really didn't see a difference in the signal quality using a scope but the display has been quite stable for the past day.

thanks for the suggestion.
/chris

Good to hear that it works.

Perhaps you couldn't see any difference because your scope acted like a pulldown. Some cheaper scopes have less than one mega ohm on their input.

/Ingvar