This is a simple calculator to compute the checksum field for the MediaTek / ETEK chipset's command extensions to the NMEA protocol. The checksum is simple, just an XOR of all the bytes between the $ and the * (not including the delimiters themselves), and written in hexadecimal. More information on the commands can be found in the NMEA User Manual.
For this to work you'll need to be using a browser that supports JavaScript and DHTML (most modern browsers do).
This page and the JavaScript it contains is in the public domain. Feel free to reuse it for any purpose.
