When the
GPS
Fix LED is blinking once per second (1Hz) then it is trying to get a fix but does not yet have one. It will turn OFF when it actively has a fix, and you can check that from
code using the .gpsFix() function.
The GPS is connected to the Serial1 UART on the Electron, and we've also provided a MOSFET to completely shut off power to it for major power savings. Pin D6 controls the GPS
power, with inverted logic. This means that the GPS will only be ON when D6 is LOW, which should keep it off even if you put the Electron to sleep.
Backup battery
There's a backup battery holder for the GPS to reduce subsequent fix acquisition times, but it's not required. This is the small coin cell (part number CR1220) holder slot. Inserting the coin
cell powers up the internal RTC of the GPS module and also help retain the satellite data in its volatile RAM. It is highly recommended that you have this battery plugged in at all times to
bring down fix times.
Accelerometer
The shield also has an on-board accelerometer, the LIS3DH. It's extremely low power so won't chew up your energy budget. The accel communicates over SPI, so it takes up A2, A3, A4,
and A5 as marked on the silkscreen of the shield. A configurable interrupt from the LIS3DH is connected to the Electron's "wake" (WKP) pin, so you should be able to make a project where
the Electron and GPS stay in deep sleep until it's hit hard enough to cross a threshold you set on the accelerometer.
Enclosure
The waterproof box includes two M4 screws for mounting the shield securely into the box. Screw the shield down in the enclosure, then plug the Electron into the shield with the USB
connector facing inward. You can also look at the silkscreen Electron outline on the board for the correct orientation. The battery and antenna can be fixed in the box using the foam
adhesive tape if you want to keep them from moving around.
Asset tracker library
We've put together a great library for you to start building from! If you're already logged into Build then you can just click on AssetTracker library and you can always open the "Libraries"
view in Build, and AssetTracker will show up under the Official Libraries. This library is especially good for learning about the Electron because it implements a couple of useful features,
like a Particle.function for checking the battery level!
Examples:
1. GPS Features - How to use the GPS efficiently, and some nice Electron functions
2. Accelerometer - Using the accelerometer with some cute tricks
GPS module specifications
22 Tracking/ 66 acquisition channels
Update rate: 1Hz (default), 10Hz (max)
Position accuracy: 2.5 to 3.0 meters
Altitude: 18000 (max)
Velocity: 515m/s (max)
Velocity accuracy: 0.05 to 0.1m/s
Acceleration: 4G (max)
Frequency: L1, 1575.42MHz
Supports up to 210 PRN channels
Supports multi-GNSS incl. QZSS, SBAS ranging
Supports WAAS/EGNOS/MSAS/GAGAN
NMEA 0183 standard v3.01 and backwards compatible
Shield Specifications