SLOW Serin2 and Serout2

so to start, my problem is that my program runs really slow. it is a basic circuit using an 18f6680 at 20MHz, a matrix orbital serial lcd and a Parallax GPS module.

Im using an old board designed for a different project, so its not possible to use the hardware serial port at this time.

the gps module needs the serout to tell it what data to send, and then it replies with the requested data. then once its returned to the PIC, it gets displayed on the serial LCD.

the "timer" part of the circuit was just so i could tell how often it cycled through the program, and with the clock from the GPS, it takes approximately 5 seconds to run through one loop from Start to start. If i comment out everything except for one piece of data ( such as just getting the number of satallites and displaying it), it still takes close to 1 second for a loop.

is there any way to optimize the code to make it a lot faster? Or do i need to use Hserin and change the gps to use NMEA data?

thanks for the help

<code>

DEFINE OSC 20


'VARIABLES

lcd VAR PORTf.7
gpsin VAR PORTb.3

valid VAR byte
sats var word
hours var byte
minutes var byte
seconds var byte
degreelat var byte
minlat var byte
seclat var word
degreelong var byte
minlong var byte
seclong var word
dirlat var byte
dirlong var byte
decdeglat var byte
decdeglong var byte
baudLCD CON 32
baudgps con 188
speed var byte

degreelong = 0
minlong = 0
seclong = 0
dirlong = 0
degreelat = 0
minlat = 0
seclat = 0
dirlat = 0
speed = 0
valid = 0
sats = 0

timer var byte
timer = 0

'STARTUP PROGRAM

startup:

Pause 800

SerOut2 lcd, baudlcd,[254,"X"] 'clear screen
Pause 200
SerOut2 lcd, baudlcd,[254,"X"] 'clear screen again
pause 200
SerOut2 lcd, baudlcd,[254,"P",140] 'change Contrast
pause 200
SerOut2 lcd, baudlcd,[254,153,0] 'change lcd brightness to 0
Pause 500


SerOut2 lcd, baudlcd,[254,"G",1,1,"V="] 'display V= on screen
serout2 lcd, baudlcd,[254,"G",1,2,"Sat="] 'display Sat= on screen
serout2 lcd, baudlcd,[254,"G",12,2,"Speed="] 'display Speed= on screen

'MAIN PROGRAM

start:
serout2 lcd,baudlcd,[254,"G",7,2,#timer]
timer = timer + 1

SerOut2 gpsin, baudgps,["!GPS", $01] 'checks for valid signal
SerIn2 gpsin, baudgps,3000,no_response,[valid]
SerOut2 lcd, baudlcd,[254,"G",3,1,#valid]

SerOut2 gpsin, baudgps,["!GPS", $02] 'checks number of satellites
SerIn2 gpsin, baudgps,3000,no_response,[sats]
SerOut2 lcd, baudlcd,[254,"G",5,2,#sats]

SerOut2 gpsin, baudgps,["!GPS", $03] 'gets time from satellite
SerIn2 gpsin, baudgps,3000,no_response,[ hours, minutes , seconds]
SerOut2 lcd, baudlcd,[254,"G",10,1, #hours, ":", #minutes, ":", #seconds]

SerOut2 gpsin, baudgps,["!GPS", $05]
SerIn2 gpsin, baudgps,3000,no_response,[degreelat,minlat,seclat,dirlat]
decdeglat = (minlat * 1000 / 6 ) + (seclat / 60 )
SerOut2 lcd, baudlcd,[254,"G",1,3,dec3 degreelat,".",dec4 decdeglat]

SerOut2 gpsin, baudgps,["!GPS", $06]
SerIn2 gpsin, baudgps,3000,no_response,[degreelong,minlong,seclong,dirlong]
decdeglong = (minlong * 1000 / 6 ) + (seclong / 60)
SerOut2 lcd, baudlcd,[254,"G",1,4,dec3 degreelong,".",dec4 decdeglong]

SerOut2 gpsin, baudgps,["!GPS", $08]
SerIn2 gpsin, baudgps,3000,no_response,[speed]
serout2 lcd,baudlcd,[254,"G",18,2,#speed]


GoTo start
no_response:
goto start

end
</code>

I hear DEBUG is supposed to be faster than any of the other software serial routines, although I do not know this as fact.

I will lay odds it is the GPS that is slow.

The Trimbles and Garmins I play with take around 2 seconds to do a loop through its data. I am not familiar with the module you have but it is probably the same as there are only a few GPS chips out there and add what ever Parallax did in front of it to receive command like ["!GPS", $05] is just going to slow the works down more.

so, that old code used 3110 bytes and took about 5 seconds to run through.

im still working on it, but i changed to using nmea data, which is something i have never been able to get working before, and its now down to 1204 bytes and cycles in 1 second!!! i think the problem was that the parallax module takes the nmea data, then rips it all apart, and only sends out what is requested. so i think going straight from the nmea to the PIC is probably a better way to do it anyways!

so heres the new code:

DEFINE OSC 20

'VARIABLES

lcd VAR PORTf.7
gpsin VAR PORTb.3
baudLCD CON 32 'baud rate for lcd
baudgps con 188 'baud rate for gps 32


valid VAR byte
hours var byte(2)
minutes var byte(2)
seconds var byte(2)
degreelat var byte(2)
minlat var byte(2)
seclat var byte(4)
degreelong var byte(3)
minlong var byte(2)
seclong var byte(4)
speed var byte(3)
decspeed var byte


course var byte(3)
deccourse var byte
decdeglat var byte
decdeglong var byte


degreelong = 0
minlong = 0
seclong = 0
degreelat = 0
minlat = 0
seclat = 0
speed = 0


'STARTUP PROGRAM

startup:

SerOut2 lcd, baudlcd,[254,"X"] 'clear screen
Pause 200
SerOut2 lcd, baudlcd,[254,"X"] 'clear screen again

'MAIN PROGRAM

start:

serin2 gpsin, baudgps,[WAIT ("$GPRMC"), SKIP 1, STR hours\2,str minutes\2, str seconds\2, SKIP 1, valid, skip 1, str degreelat\2,str minlat\2, SKIP 1, str seclat\4, SKIP 3, str degreelong\3, str minlong\2, SKIP 1, str seclong\4, SKIP 3, str speed\3, SKIP 1, decspeed, SKIP 1, str course\3, SKIP 1, deccourse]

SerOut2 lcd, baudlcd,[254,"G",1,1, " TIME=", STR hours\2, ":", str minutes\2, ":", str seconds\2, " ", valid, 254,"G",1,2, str degreelat\2, str minlat\2,".", str seclat\4," ", str degreelong\3, str minlong\2,".", str seclong\4, 254,"G",1,3, str speed\3,".", decspeed," ", str course\3,".", deccourse]


GoTo start
end


I will try changing to DEBUG sometime and see what happens, and im going to keep playing with this, but if anyone knows a better or more efficient way of doing this, let me know..