Calculating and validating nmea checksums
Hi All Does anyone have any idea how to calculate the checksum for the SIRF binary protocols. For instance if I wanted to find the checksum for $PSRF105 An example SIRF message is $PSRF105,1*3E If I can calculate the checksum I can use extra capabilities within my GSM/GPS module. I have seen a similar format as you've shown, I just wasn't sure how to implement it.I need to include a checksum calculator within my proton code as some parts of the message will contain things like telephone numbers,vehicle name etc that need to be calculated for when the code constructs the message. I have the checksum calculator application also and can generate checksums for known messages.This is fine for a library of messages and I will be using some set messages with constant checksum.
It calculates checksums of functions: md5, sha1, sha256, sha384 and sha512.NMEA sentences checksum calculator is a Java-based software application designed with a single goal in mind: to help you calculate and verify NMEA sentence checksum used with GPS devices. At the end of the sentence, the asterisk is followed by a checksum represented by a two-digit hexadecimal number.The goal of the utility is to calculate the exact two digits found at the end of the NMEA string.Otherwise, a checksum of 0x05 would be sent as the string "5" instead of "05".Regards, Mike Thanks Mike Hadn't got round to trying it out yet as my gps kit has been out on demo.