What am I doing wrong?

GPS/GNSS
1

I have a Pro Micro connected to a uBox neo M10 from Sparkfun with TX on the PM connected to the GNSS via a voltage divider so the 5V level on the PM is 3V on the GNSS.

I run Paul’s code to stop all NEMA sentences and poll for just GGA and it works fine. This proves that my Pro Micro TX to GNSS RX path is OK.

Then I want to change from the default CFG-NAVSPG-UTCSTANDARD from PORT to AIR1 so I get altitude data above 12,000 meters. Others have used Paul’s code to make this change and it worked. I want to directly change this parameter by sending the GNSS the proper sequence of bytes to prove to myself that I understand the spec sheet.

I sent the following hex values to the GNSS:

B5 62 06 8A 09 00 01 00 00 20 11 00 1C 06 ED BA

but I get no ACK response.

Where did I go wrong?

Thanks in advance,
Rick

2

It’s CFG-NAVSPG-DYNMODEL, and the key# is encoded little-endian
So “21 00 11 20 06”
I didn’t check the fletcher sums, but if those are wrong the packet will be ignored.

3

Sum/Form is also wrong. The length of 9 bytes is encoded as 16-bit, not 8-bit

1 Like
4

I now see all of my mistakes and it now works.

Thank you for your invaluable assistance.

Rick