GNS 202/902(B) StarterKit
confidential information manual
© GNS-GmbH 2014
V 0.2, Oct 24th 2014
4GNS 202/902 configuration
In all cases, where a UART or USB connection to a PC is available, the GNS 202/902 Starter Kit
offers a comfortable way to reprogram the firmware options or settings using the bidirectional NMEA
command interface.
Note:
Removing the power of the GPS device will effect that any modified setting will be lost
and reset to factory default settings. If the module has backup power supply through
VBACKUP, it will be able to keep the modified setting until the backup power is exhausted.
After selecting the preferred settings or features at the NMEA_Interface_manual_MTK_Vx
document, first the checksum has to be calculated for this command, refer to chapter 5.1 Checksum
Calculation. To execute the $PMTK commands, use a terminal program of your choice (for example
HyperTerminal, HTerm, TerraTerm,… available as part of your WindowsOS or as freeware).
Use the COMport setting as explained under 3.1.
Use the PMTK-Commands attaching the calculated checksum (see 5.1) and the Carriage Return
sequence at the end of each command line. Most terminal programs offer the option to attach Carriage-
Return (use option add CR-LF or similar).
4.1 Checksum Calculation
To execute the a $PMTK command it is required to terminate the command by *<chksum>and a
<CR><LF>. The checksum calculation is simple, just XOR all the bytes between the $ and the * (not
including the delimiters themselves). Then use the hexadecimal ASCII format.
Or use the checksum tool at the \Software\Checksum tool folder, which is available on Starter Kit CD or
at the GNS forum: www.forum.gns-gmbh.com.
Example: $PMTK226,3,30*4<CR><LF>
