It looks like that code is setup for 9600 baud. I don't remember running the backpack at 9600 baud before so I should probably check it out in the simulator and make sure my delay subsystem supports that baud rate. I may have done that already but I don't remember. Give me a few to check it out and I will get back to you...

If this is a problem that I caused, I apologize...

Mike,

You don't owe me anything, much less an apology. I am just grateful for you sharing your code and your time. And as I previously posted, don't let this be a burden for you. You have no obligation to me whatsoever.

 

Who doesn't love a good mystery (grin).

I can't see anything wrong while simulating control code values in the $94 (line 3) and $D4 (line 4) range. Time to try this on real hardware, which may take a while.

Hang in there...

Cheerful regards, Mike

 

Who doesn't love a good mystery (grin).

I can't see anything wrong while simulating control code values in the $94 (line 3) and $D4 (line 4) range. Time to try this on real hardware, which may take a while.

Hang in there...

Cheerful regards, Mike

Attached is my code in case you want to try it. I included a txt file, pbp file, asm file, and hex file, all zipped in one folder. The code should exhibit the problem I have previously described. Here's the way it looks on my display; "by" is supposed to be on row 3 by itself.

 

Hi MMcLaren and tracecom,
I understand that this is an old thread, but I am a newcomer to the PIC party. I am looking for a simple LCD backpack, and it doesn't get any simpler than this. Do you have any finished firmware for this hardware, preferably for a 2 line by 16 character display. I do not want the tester firmware, but the backpack firmware.
Thanks and regards,
Mikejp56

 

Tag @MMcLaren and @tracecom to send them an alert for quicker response.

 

Tag @MMcLaren and @tracecom to send them an alert for quicker response.

Hi JohnIn TX,
i do not understand what you mean. How do I do that?
Regards,
mikejp56

 

Don't worry, I just did @mikejp56
If you 'tag' someone, it will show up as an alert when they visit and give them a fast-link to the thread.
To enter a tag in your post, start with the 'at sign' and type the first few characters of their username. A list will appear with suggestions and you can click from there.
You can also quote or 'like' a post (encouraged if its useful) and the poster will get an alert from that.
Welcome aboard.

 

Don't worry, I just did @mikejp56
If you 'tag' someone, it will show up as an alert when they visit and give them a fast-link to the thread.
To enter a tag in your post, start with the 'at sign' and type the first few characters of their username. A list will appear with suggestions and you can click from there.
You can also quote or 'like' a post (encouraged if its useful) and the poster will get an alert from that.
Welcome aboard.

Hi JohnInTX,
Okay, thanks for the tips!
Regards,
Mikejp56

 

Hi mikejp56,

Here is source (assembly language) + hex for 12F683 at 9600 baud. For a different baud rate, modify one line in the source and re-assemble (absolute address mode)... Schematic shows a 12F635 but it's the same pinout as the 12F683.

The Serial LCD Backpack performs a complete HD44780 "initialize by instruction" procedure on power-up so the backpack doesn't start looking for serial data from your host until about 75-msecs after power-up. Every Command character must be preceded by a 0xFE character (which sets RS=0 for the following 'command' character). Data characters (RS=1) are the default.

Cheerful regards, Mike, K8LH

 

Hi Mike,
Thank you for your timely and informative reply. I am at my bench now and will start experimenting with this ASAP.
Respectfully,
Mikejp56

 

You're welcome. Good luck & have fun.

Speaking of simple LCD Backpack designs, don't overlook the many designs using shift registers. For example, here are a couple designs that drive the LCD in 8-bit mode while providing a 2 pin interface to the host.

 

Hi MMcLaren,
Thanks for those 2 schematics. I have plenty of things to work through now.
Regards,
mikejp56

 

Hi Mike,
Thanks for all of you information. I have hit a snag and I do not know where to turn. I initially tried your K8LH serial LCD backpack with the Serial LCD Tester mentioned in this thread, but I couldn't get anything but nonsense characters that were constantly changing on the screen. Next I tried the Serial LCD Tester with the serial backpack program from the MeLabs website's examples page for 16F887. Again no success. I tried just programming the Serial LCD Tester to output a single character, and still no luck. The Serial LCD Tester is outputting data; I can see a data stream on my scope. The K8LH serial LCD backpack outputs do not change with serial input. It appears that something is amiss with the Serial LCD Tester because that is the common item in both scenarios.
Any help or insight would be greatly appreciated.
Regards,
Mikejp56