NMEA CheckSum Routine

[Art]

I'll have a go,

'mode 188 is 4800 baud @ 4MHz.


'
SendByte:
serout2 portwhatever,188,[array_byte] 'send array byte
return
'
cksum = 0
array_byte = "$" 'send "$" qualifier
gosub SendByte '
For index = 1 to 35 '
array_byte = WPT_array[index] 'copy array byte to serial buffer
gosub SendByte 'send data byte
cksum = cksum ^ array_byte 'calc checksum
Next index '
array_byte = "*" '
gosub SendByte '
array_byte = cksum 'load checksum into serial buffer
gosub SendByte 'send checksum
'

Cheers, Art.

[acjacques]

I have followed the the suggestion and i wrote this code that is now working in the magnetic compass.
heading is my compass variable (001 ~359)
crc is the nmea checksum

crccalc:
crc= "H"^"D"^"M"^"," ^ ((heading DIG 0)+"0") ^ ((heading DIG 1)+ "0") ^ ((heading DIG 2)+"0")^"."^ "0"
Return

the output is like this:
$HDM,279.0*4F


acjacques