ublox NEO-M8T Pi Hat

Paul Theodoropoulos paul at anastrophe.com
Sun Apr 21 01:07:29 UTC 2019


I managed to fry my previous M8N board that I'd cobbled together some time 
back. Poking around on ebay I ran across a slick little pi-zero 
form-factor HAT  with M8T and onboard replaceable battery. Wired up PPS, 
and have it up and running. Took some poking at the ublox u-center to get 
it spitting out the 'right' nmea info, though no idea if all the strings 
are necessary (most of the thousand or so configs in u-center are far too 
arcane for my understanding).

Initially it was just pumping out long hex strings - not garbage, specific 
hex. Now I have it putting out NMEA - but there's still one string in the 
output in hex, and i'm not really sure what it is or how to fix/hide it, 
or if i even need to bother? - example from gpsmon:

(43) $GNGST,002725.00,2885796,,,,6.7,5.6,14*5D
(38) $GNZDA,002725.00,21,04,2019,00,00*77
(40) $GNGBS,002725.00,6.7,5.6,13.7,,,,,,*6A
(33) $GNVLW,,N,,N,0.000,N,0.000,N*44
------------------------------------- PPS 
-------------------------------------
(376) 
b562021570015eba490c02009a400208120b0101fcc8397c24fc914e744191f281f0aaad9a4167f8b6c3000200000000120b0f0c01009
ee48964bce273416b77e5d8ff1f9a413c795744000c0000000018090f0a01005ad7aa9ee615754147313c508ab39b41bff51ac500060000f4fb
1c0703080f0033582e31261e7841cab259e857af9f4178ed01c502210000f4fb1d0702080700a47deb9e088c75419107df1fbd4e9c4134636e4
4021800000000150b0f0c010022c799feeb877741f8519f3bfbe99e41d4f6e8c4021f0000000018090f0a0100e5aa2e12554173410febae3926
c09941c7d2bfc40617000af4fb1d06030807006ab4e582d2fe72418049eab1cb5b99419c47b4c4060d000500000e0b0f0c01007b2bb5ac02597
441ba6e894fbc1d9b417cd42545060e00000000180a0f0b0100c5e74929784f7b41b93ed3818df0a141318046c50201000000000f0b0f0c0100
(36) $GNDTM,W84,,0.0,N,0.0,E,0.0,W84*71
(70) $GNRMC,002726.00,A,3819.91911,N,12241.32940,W,0.013,,210419,,,A,V*00
(35) $GNVTG,,T,,M,0.013,N,0.025,K,A*38
(76) 
$GNGNS,002726.00,3819.91911,N,12241.32940,W,AAAN,17,0.83,26.1,-29.2,,,V*18

One "neat" thing is that I'm getting three SHM outputs - SHM(0) GPS, 
SHM(1) PPS, and SHM(2) PPS. The differences between the two are trivial, 
but ntpsec does select the non-preferred one as one of the reference clocks.

The seller doesn't appear to have any more at this time, but I've put up 
some screenshots from the listing as well as the board now as I'm 
finishing up the build.

ebay listing: https://i.imgur.com/sdBlMFW.jpg
Top of board: https://i.imgur.com/UdUbd1R.jpg
Bottom: https://i.imgur.com/WRG9Vth.jpg
Schematic: https://i.imgur.com/4CLsCiQ.png
Ready to deploy: https://i.imgur.com/qJuSn42.jpg

-- 
Paul Theodoropoulos
www.anastrophe.com



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