Bangle.js 2 GPS low level communications

Hi! I know in the past we've had a few posts about sending messages to the GPS chip:

• https://forum.espruino.com/conversations/371336/?offset=25#16332430
  
• https://forum.espruino.com/conversations/371360/
  
  

And we pretty much left it with the AGPS uploader thats now in BangleApps which lets you add the GPS ephemeris data and increase your time to fix, but there were extra things that could be done like telling the GPS the approx location with the AID-INI command.

I've finally had some decent success with this, and have documented it (with code) in:

https://github.com/espruino/EspruinoDocs/blob/master/info/Bangle.js2%20Technical.md#gps

It'll be in https://www.espruino.com/Bangle.js2+Technical eventually but I haven't updated the main site with it yet. I'd be interested to see if anyone has any luck with this - specifically @HughB as you were trying initially? On a device where the battery has been completely disconnected (I have one for testing), if I:

• Reconnect power and boot (inside, by the window)
  
• Upload AGPS
  
• Run the AID-INI command
  
  

I see a time to fix of 27sec, whereas just uploading the AGPS I see 90s (not that I have tried this very many times).

If this ends up working, it's something that could maybe be added to the AGPS uploader app as it could get the current user's location and put that in automatically.

I saw anecdotally on some UBlox forum that perhaps just specifying time + location without the ephemeris data may not help that much. I haven't done tests, but it feels like it wouldn't hurt.

One more note: it's very badly documented - I'm working from a translated datasheet: https://github.com/espruino/EspruinoDocs/blob/master/files/CASIC_en.pdf

... but maybe now we have something a bit more stable to send/receive data someone might be able to figure out how to put the GPS into lower power modes. I'm happy to try out commands here if you can find some the succeed (the parsing code detects ACK-ACK).

Shame there wasn't much interest in this. I've just put AID-INI into the assisted GPS updater (in the development app loader at the moment) so hopefully everyone will start seeing much faster GPS locks soon.

Thank you for this work and all you do for Bangle.js 2! Very happy with mine that arrived a few days ago :)

@Gordon, this is great news. I’m sorry that I didn’t see this post earlier. I will test the new GPS updater and report the results.
Thank you so much for your continuous effort on this matter.