How do I discern Maidenhead Locator from GPS lat long info.

[richard]

this is how I would go about parsing nmea, for what you are doing there is little point in storing all the data just to display it
only store what is needed for calculations or enhanced display.
I would also read in the entire nmea sentence using $ ast the start marker and * as the end marker.
when you have a complete sentence send it off for parsing if its the correct sentence type

 '****************************************************************
'*  Name    : NOKIA_DEMO.PBP                                     *
'*  Author  : richard                                            *
'*  Notice  :                                                    *
'*          :                                                    *
'*  Date    : 16/5/2018                                          *
'*  Version :  mssp1 version  with bigtxt                        *
'*  Notes   :                                                    *
'*          :FOR pic 16F1847@32MHZ           NOKIA               *
'****************************************************************
#CONFIG ; 16FF1847.
        __config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_ON & _MCLRE_ON & _CP_OFF & _BOREN_OFF
        __config _CONFIG2, _PLLEN_OFF & _LVP_OFF
#ENDCONFIG
define      OSC         32
 
; --- *** Oscillator  *** ---------------------------------------------------
OSCCON = %11110000           ;32 MHz, 
ANSELb = 0
ANSELA = 0
TRISA=%10010000
TRISB=%11101011
ch var byte
BUFF VAR BYTE [16]
 ;DEFINES FOR DISPLAY   use   font7x5_16.bas   or  font7x5_18.bas     for pic18
 #DEFINE PIC16 1            
 #define use_mssp 1
 lcdheight con 5      ;  6 PAGES   
 lcdwidth  con 83     ; 84 PIXELS WIDE
' LCD_CLK     var     LATB.4       ' SCK1     pin needs to be set as dig o/p
' LCD_DIN     var     LATB.2       ' SDO1     pin needs to be set as dig o/p
 LCD_RST     var     LATA.4 
 LCD_DC      var     LATA.3
 LCD_CE      var     LATA.6
 LCD_LIGHT   var     LATA.0
nmea var byte[80]
h var byte
m var byte
s var byte
Include "nokia_ds.INC"  ' bring it in
include "font7x5_16.bas"
@ #DEFINE   TOKEN_DESTROY 1
include "strtok.pbpmod"
'==========================    MAIN  Routine    ==============================
    gosub lcd_init
    LCDCLR
    ARRAYWRITE BUFF,["READY",0]
    LCDSTR  5,0,BUFF 
    PAUSE 1000
    LCDCLR
  
looper:
'start=$ end=*
arraywrite nmea,["GNRMC,090045.000,A,3823.6645,N,02353.3600,E,0.02,195.80,170518,,,A",0] 
;STRLEN nmea
strtok nmea,0,","
LCDSTR  0,0,nmea    ;sentence type
strtok nmea
ARRAYREAD  nmea ,[SKIP (STRTOK_INX-STRTOK_LEN),dec2 h,dec2 m,dec2 s]
arraywrite buff,[dec2 h,":",dec2 m,":",dec2 s,0]
LCDSTR  36,0,BUFF 
strtok nmea ;fix
strtok nmea ;fix
arraywrite buff,["lon",0]
LCDSTR  0,1,BUFF 
ARRAYREAD  nmea ,[SKIP (STRTOK_INX-STRTOK_LEN),str buff\16] 
LCDSTR 20,1,buff 
strtok nmea
ARRAYREAD  nmea ,[SKIP (STRTOK_INX-STRTOK_LEN),str buff\16] 
LCDSTR 77,1,buff 
strtok nmea
arraywrite buff,["lt",0]
LCDSTR  0,2,BUFF 
ARRAYREAD  nmea ,[SKIP (STRTOK_INX-STRTOK_LEN),str buff\16] 
LCDSTR 13,2,buff 
strtok nmea
ARRAYREAD  nmea ,[SKIP (STRTOK_INX-STRTOK_LEN),str buff\16] 
LCDSTR 77,2,buff 
strtok nmea
arraywrite buff,["speed",0]
LCDSTR  0,3,BUFF
ARRAYREAD  nmea ,[SKIP (STRTOK_INX-STRTOK_LEN),str buff\16] 
LCDSTR 36,3,buff  
strtok nmea
arraywrite buff,["hdg",0]
LCDSTR  0,4,BUFF
ARRAYREAD  nmea ,[SKIP (STRTOK_INX-STRTOK_LEN),str buff\16] 
LCDSTR 36,4,buff 
strtok nmea
ARRAYREAD  nmea ,[SKIP (STRTOK_INX-STRTOK_LEN),dec2 h,dec2 m,dec2 s]
arraywrite buff,[dec2 h,"/",dec2 m,"/",dec2 s,0]
LCDSTR  36,5,BUFF 
  
   
    
END