GPS to PIC to LCD

[Alienbeing]

This is a project which was provided in EPE mag. 2004-01 called GPS to PIC to PC. I translated the .asm code to MPASM and compiled to Hex. The basis of this code is to grab NEMA sentences from GPS by RS232 and display portions of it on a 2x16 LCD module. I have created a proteus simulation and loaded 16F877 PIC with the code but it does nothing but generate errors about The LCD controller receiving data while busy. I can't figure out what the cause of this is. Maybe someone can offer some advice it would be greatly appreciated. I have included all the code .ASM, .HEX, and Proteus file. I don't have much experience in assembly. I do understand some of this code but not enough to figure out why it's not working correctly.

http://rapidshare.com/files/67889296/GPS_to_PIC.rar.html

Thanks,
Alienbeing

[Alienbeing]

Well, I've been digging into this code more and see that it contains no routines to check the busy flag on the LCD. The programs hangs on trying to clear the LCD. I managed to remedy other errors in the code so now it compiles without errors, or warnings. I guess I will try to put in checking for the busy flag. I'm still not very good at assembly but it's getting easier to figure out what this code it doing or not doing. If I succeed in this I'll post an update to the source for others to use if they want to view NEMA sentences from a GPS to an LCD module using a PIC.

Alienbeing

[user112]

It is not need to verify busy flag if you wait enough time between send informations to LCD (put in the routines for transmiting data to LCD an temporization) .
In simulation you can rise (just for test) the frequency of the LCD from properties to remouve errors

[Alienbeing]

Thanks, I was considering doing that too, but thought that once I build the circuit I would probably need to use the Check Busy Flag on the LCD before sending the code to the PIC.

Thanks again.
Alienbeing

[user112]

I made many programs in this way and works very good also in reality

[Alienbeing]

Thanks, for the help. I finally got this to work in Proteus 7.1 SP1.  If anyone is interested
I can repost my working asm code and Proteus file. I did have a few asm bugs (corrected) but it working fine now.
Still have not programmed the code into the a Real Pic yet to test the circuit. That will be in about a week I
guess. I still need to alter some of assembly code to make some minor changes for the LCD display.

Alienbeing