Help File Serial LCD Help Please

Brian Carpenter

I am hoping that there are a few others in the group that have tried the code in the SX/B help file for the Serial LCD.· I am having difficulties getting this to work.· I puchased several LCD's form Sparkfun.· they are the white on black displays with backlight.· I reallize that the code does not control the backlight, this is not a concern.· i am going to wire it on continuously.· I have not been able to successfull make the code work yet.· I have followed the connections.· i have the pullup resistor on the serial I/o and i have a pulldown on the RA.1 line.· I have breadboarded it on a PDB board and then rebreadboarded it on another PDB.· No dice on either.· i took a risk and removed the serial LCD backpack from a 2 x 16 display purchased through parallax and installed it on this display.· It works perfectly.· So surely i am missing something.· Anyone have any ideas? I could really use the assistance.

Brian Carpenter


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It's Only A Stupid Question If You Have Not Googled It First!!

PJAllen

How about running one of those as a "4-bit", as shown in this link, using the program there that I re-wrote into SX/B?· http://forums.parallax.com/showthread.php?p=688602

I have found that all LCDs are not created equal.· The Busy Flag, which starts on the falling-edge of the Enable pulse,·takes longer to pass in some than in others.· Parallax's may be faster than others.

JonnyMac

Brian,

It must be something simple -- I created that program and had it working in a couple hours and have built it up many times. I will respectfully disagree with PJ, though, as 4-bit mode is a pain in the backside and actually makes things more difficult.

I've attached an updated version of the help file serial LCD (this is part of my Practical SX/B project). Note, though, that this version is SEETRON compatible on the serial side, that is, it uses inverted comms. If you want true mode comms simply use a pull-up on the serial line and change the Baud constant to OT9600. This version of the program does indeed monitor the busy flag.

PJAllen

Hey, it's cool.

I was advocating the "4-bit" attempt as a trouble-shooting aid, to establish an operational baseline (if it won't work that way... then I don't know, man.)

Brian Carpenter

i will not be using the serial com part of the code after i verify that it works. I am trying to make a devices that when the contact is open, it will display one message and light a red led and then when closed display a second message and light a green LED.

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It's Only A Stupid Question If You Have Not Googled It First!!

Brian Carpenter

Ok John and all

I can make it write to the first line but not the second. Any ideas?

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It's Only A Stupid Question If You Have Not Googled It First!!

JonnyMac

As PJ pointed out earlier, not all LCDs are created equal, and some use odd addressing schemes. Make sure you have the multi-line conditional compilation constant defined and check with the LCD vendor on display addressing -- sometimes they can be odd.