I’m using MiniGPS to set a few parameters (messages, update rate and baud). This works well. I con power off the GPS and it retains these settings.
However, it seems that after a few days the GPS reverts back to its factory settings. Unless, that is, it’s been powered up for more than a few minutes in circuit???
Could it be that the LS20031 is using battery backed up RAM instead of flash to store its configuration?
I’ve put in a support request to Locosys, nothing back yet.
Dear Paul, This is Eric Chin, sales account manager of LOCOSYS Technology Inc. Thank you very much for your email as well as using our product. Some of PMTK commands are temporary saving at module SRAM only. It will go back default setting when the backup battery exhaust its power. If customer want to keep some parameters and configurations be saved the backup battery need to fully be charged (the measured voltage of backup battery should be higher than 3.2V). The fully charged battery can keep about one week the parameters and configurations saved. Hopefully this info helps.
So don’t rely on any PMTK set configurations lasting more than a week.
From memory, the Logosys LS2003x modules can have settings written to flash, but only a finite amount of times (something like 5-10).
Locosys have the ability to do so, as you can order modules with the parameters you want, but as far as writing and saving these parameters yourself I am not sure. I have not come across the means to do so yet, although it could be as simple as a $PMTK command.
Specifically look at the PMTK_API_SET_USER_OPTION command. Note it says that usually you’ll only get to do that about eight times before you have to erase the flash, but of course they don’t document what that command might be.
Thanks for that, PMTK_API_SET_USER_OPTION would be a good option. I feel a little dumb for missing it.
What I ended up doing for my application (APRS for model rockets) is have a routine that blindly sends the configuration commands to the GPS at all baudrates from 57600 down to 4800. Takes a few seconds but it pretty much guarantees the config will be right. It also means that the project should work with any GPS.
Well sounds like the LS20031 does not have onboard flash to write user options to or it is disabled in firmware. Who knows. I wish these vendors who use the mediatek’s chipset would actually release us full documentation on their product instead of the same old half-ass’d references as usual.
