GPS Module Initialisation option

[raintonr]

Thank you so much for this awesome utility. I built a Bluetooth gateway in one afternoon with ESP32 + Neo-M8:

The only thing missing, at least in this context, is an option to write configuration settings to the GPS module at power on.

Scenario is this: the Neo-M8 can allegedly support concurrent reception from 3 GNSS but that isn't default behaviour (default is GPS & GLONASS). The most economic version of this package is the NEO-M8M which does not include flash so if one therefore wants to use something other than default GPS & GLONASS the command to switch GNSS in use has to be sent at power on.

[nopnop2002]

Where can I find command documentation for using anything other than the default GPS and GLONASS?

[raintonr]

The spec is here: https://www.u-blox.com/sites/default/files/products/documents/u-blox8-M8_ReceiverDescrProtSpec_UBX-13003221.pdf

Seems like UBX-CFG-GNSS is the required command.

There may be some clues in this project (only just found this - I should have experimented with it before boxing up my project and installing in a vehicle - doh!) https://gpsd.gitlab.io/gpsd/ubxtool.html (https://gitlab.com/gpsd/gpsd)

[nopnop2002]

Thank you for information.

Seems like UBX-CFG-GNSS is the required command.

To try this, I need to buy NEO-M8M.

[raintonr]

If you could suggest where to start I could try and make some changes and if they work submit a PR?

[nopnop2002]

Thank you for your offer.

Unfortunately, the current code cannot send UART.

It needs to be reviewed from the ground up.

[raintonr]

At first thought, one could place some code in app_main() to open UART, write command string, close UART and carry on a usual.

I would imagine an optional 'GPS init command string' configuration option would be needed (along with TXD pin). If this is set, the string is sent to the GPS module on power-up, otherwise ignored.

Do you see any problem with such an inclusion?

[nopnop2002]

That looks like a good idea. I'll try it.

[raintonr]

There is a utility here http://wiki.openmoko.org/wiki/Neo_FreeRunner_GPS (see UBX protocol section) for appending header & calculating checksum for these devices, so the use case for me would be:

1. Figure out exactly what UBX-CFG-GNSS I need.
2. Use ubxgen.py script from above page to create necessary ublox configuration packet.
3. Copy/paste configuration packet into build configuration for esp-idf-GPS-Repeater.
4. Connect TX and configure TX Pin.
5. Rebuild & flash updated esp-idf-GPS-Repeater.
6. Cross fingers! ;)

[raintonr]

1. Figure out exactly what UBX-CFG-GNSS I need.

There are some good clues here: https://github.com/renatobo/bonogps/blob/main/hardware/GPS/README.md#gps-sbas

[jessejgm]

I can parse nmea messagens to send over bluetooth?

[nopnop2002]

@jessejgm

I can parse nmea messagens to send over bluetooth?

Yes. It works for GPS Server for Bluetooth GPS. It works for Acceptor.

I use this initiator. https://play.google.com/store/apps/details?id=googoo.android.btgps