Link to a NMEA calculator on web: http://www.hhhh.org/wiml/proj/nmeaxor.html
ex: $GPGGA,045104.000,3014.1985,N,09749.2873,W,1,09,1.2,211.6,M,-22.5,M,,0000*62"
Elimeléc's Arduino Projects: NMEA checksum calculator
excerpt: Generates a two nybble hex value for an ASCII string surrounded by $ and *
if (data_end == true){ for (byte x = start_with+1; x<end_with; x++){ // XOR every character in between '$' and '*' CRC = CRC ^ buffer[x] ; } } if(CRC > 0){ Serial.println(CRC,HEX); // print calculated CS in HEX format. CRC = 0; // reset CRC variable data_end = false; // Reset EOF so we can process more incoming data. }
A complete example and explanation is in a later post above.
