This code will compute the checksum as used by GPS message strings ( $GPRMC, etc)
Python, 12 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 | #don't include initial "$" or trailing "*XX"
item = "GPRMC,004422.767,A,3601.9719,N,07950.6023,W,0.00,,180804,,,A"
#should return a "*6F"
s = 0
for i in range(len(item) ):
s = s ^ ord(item[i])
checksum = "*"
#convert to hex
s = "%02X" % s
checksum += s
print "Checksum: %s" % checksum
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Using the checksum helps verify the GPS data you are using. In my project this code helped isolate a communication problem that could have caused major problems later on.
