Very nice boosterpack with an awesome form factor
For GPS BoosterPack
First off a couple of general comments. I had not too much time to play with the item yet, so some things might need updating later.
The pinout of the BP is straight forward on the TIVA LaunchPad. RX/TX connect to U1TX/U1RX respectively, and PPS is hooked up to PE5.
The GPS module itself is a Quectel L80, with documentation readily available on the internet. The L80 is based upon a MediaTek MT3339, hence GPS only. V_BCKP is directly connected to VCC, so no backup battery, thus EASY/AlwaysLocate are not supported. The L80 implements LOCUS, which means one can use the MT3339 internal flash to log data. Quectel configured it for basic logging content, UTC time, fix type, lattitude, longitude and height. One should note though, that LOCUS requires about 64KB of memory to be parsed due to the layout of the data. The TM4C123GH6PM on the LaunchPad I used has only 32KB, so parsing the log is only possible offline. The NMEA protocol implemented by the L80 will emit 4 fractional digits for longitude and latitude. This results in a resolution for the position reports of 18cm worst case at the equator (UBLOX units have a 1cm resolution in binary mode). The only unexpected thing I overlooked in the documentation initially is that the L80 always sends a GPTXT message per position fix indicating as to whether the internal or external antenna was used. This sentence cannot be disabled according to Quectel support.
I did test the unit with a USB bridge over to a PC to check out the protocol in use and various features like static threshold, AIC and so forth. Got a really nice fast fix on my frontporch (have to admit I did less testing due to the cold temperatures). 7 GPS satellites in use, plus one WAAS satellite.
My 2nd test was with the unit attached to a Launchpad and an SDCARD for logging purposes. It was placed directly over a local GPS reference marker that is fairly easy to access and free of obstacles. Turns out that the unit was rather precise with a CEP of more or less 0.5M. Almost no static drift over the whole period. I will not quote any specific values, as this was done is a cold and snowy night, so might not be that representative.
I do really like the formfactor. The L80 is a nice replacement for say a UP501, and definitively way more cost effective than say a comparable PAM-7Q.
My original intention was to use this BP along with an IMU for an autonomous rover. There the mentioned position resolution is a tad of an issue compared to UBLOX 6 or UBLOX 7 based systems. On the other hand, the static drift turned out to be way better.
