Fix typo in GNSS_MODEL defination and usages for the UC6580

[GPSFan]

Correct the $CFGSYS init string for the UC6580 to init the receiver for: GPS L1 & L5 + BDS B1I & B2a + GLONASS L1 + GALILEO E1 & E5a + SBAS

Fixes Bug #2983

The protocol spec provided on the Heltec download site is for an older version of the Firebird series. the correct protocol spec is available at:
https://en.unicorecomm.com/products/detail/34
where 1.4.2.5 CFGSYS: Configure Satellite System
describes the much expanded command for the Firebird II chips of which the UC6580 is one.

[CLAassistant]

All committers have signed the CLA.

[thebentern]

Great fix! If you can sign the CLA, I'll get this merged

[thebentern]

@GPSFan given your username, maybe you can help with another GPS model issue. I've been unsuccessful with attempts to put an ATGM336H module into standby mode for power savings via UART. I assumed that it would follow the MTK style commands ala the L76K. That has not proved to be correct in my experience though. If you have any insights on this or know where to dig up a more comprehensive datasheet, that would be swell.

[GPSFan]

I'll take a look, I have no experience with the L76 or the ATGM336H modules, so any pointers to the relevant docs would be helpful.

[GPSFan]

Looking at the datasheet for the AGTM336H:
https://www.icofchina.com/d/file/xiazai/2016-12-05/b5c57074f4b1fcc62ba8c7868548d18a.pdf
I found a reference to the protocol spec:
CASIC multi mode satellite navigation receiver protocol specification
https://espruino.microcosm.app/api/v1/files/68b597874e0a617692ebebc6a878032f76b34272.pdf
There it describes the $CAS12 command to put the receiver into standby, BUT they also imply that only the -5L low power variant supports that command.
I saw your code in the l76-soft-standby branch and the command you send to the L76 is very different.
I haven't looked for the L76 docs yet so don't have a clue as to how similar or different the hardware is.

[code8buster]

#2963
I also suggested that. We discussed it on the Discord, and the CAS12 command had no effect; likely for the reason you stated. The PMTK reference comes from the Quectel L76 protocol document.
https://forums.quectel.com/uploads/short-url/7THMsVAcMkh8pFZM87JHj1b5zXa.pdf

[GPSFan]

Thanks for that spec link, it seems the L76 and the AGTM336H are very different beasts software wise.
Using the CAS06 command might return some definitive product info on whether the individual module is a low power one or not, then again it might not...

[code8buster]

The only ones I've seen available to consumers is the ATGM336H-5N module, and not the 336H-5L

[GPSFan]

Yeah, the ones that filter out to us outside of CN are never the ones you want. ;>(
The ATGM336H-5N is a fairly old module, I'd be looking at something M10 based for new designs, THe T-Beam supreme has an M10 option, I have an M10 I got off Amazon that works quite well with a very small antenna. Hopefully, the CN modules will inspire the folks like u-blox to do an L1/L2/L5 that is affordable, well documented and, well, uhh .....

[geeksville]

This pull request has been mentioned on Meshtastic. There might be relevant details there:

https://meshtastic.discourse.group/t/no-gps-module-t-echo/8824/2