I have got the following GPS Adafruit Ultimate GPS Breakout

I want the GPS to only output the GPS information in $GPRMC. I am able to do that with this command: $PMTK314,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*29\r\n. The problem is I can't get the GPS to commit the changes to it's ROM so I don't have to change its settings every time it restarts. Is there any command to do that?

Another related question, why does the GPS send multiple sentences seems a bit redundant.

Following are the datasheets & command set:

1.PMTK command packet

2.GPS Standalone Module Data Sheet


That doesn't appear possible for those modules, from the programming guide:

Those command packet for module baud rate and update rate changed only temporary, when module power reset those update rate and baud rate must be back to original setting. If user want to change baud rate and update rate of module to other value that need GTop re-edit new firmware and burning it to module.

One good reason for a manufacturer to do that is to essentially make it 'unbrickable' when placed in-circuit. Imagine otherwise if an error caused the baud rate to be set inadvertently to a baud rate your system couldn't support, it would require removal of the module rather than a simple power cycle to recover from.

The multiple NMEA sentences is largely for historical purposes when traditionally all receivers were 4800BPS with a 1Hz maximum output rate. The default set normally gives all the most useful sentences out of the receiver at that rate so it will work with a wide range of applications.

Personally unless there's a good reason not to I normally write code to parse out only sentences required and ignore the others. That way your software will continue to operate properly if the receiver reboots unexpectedly or the configuration doesn't get set for some reason.


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