- Technical Details
- Questions & Answers
This is the Ultimate GPS module - The Version 3 board comes with the latest module which has external antenna support and pulse-per-second output.
We really like the latest-and-greatest GPS module from Adafruit. Here's why:
- -165 dBm sensitivity, 10 Hz updates, 66 channels
- 5V friendly design and only 20mA current draw
- Breadboard friendly + two mounting holes
- RTC battery-compatible
- Built-in datalogging
- PPS output on fix
- Internal patch antenna + u.FL connector for external active antenna
- Fix status LED
The breakout is built around the MTK3339 chipset - a, high-quality GPS module that can track up to 22 satellites on 66 channels, has an excellent high-sensitivity receiver (-165 dB tracking!), and a built in antenna. It can do up to 10 location updates a second for high speed, high sensitivity logging or tracking. Power usage is incredibly low, only 20 mA during navigation.
Best of all, Adafruit added all the extra goodies you could ever want: A ultra-low dropout 3.3V regulator so you can power it with 3.3-5VDC in; 5V tolerant inputs; ENABLE pin, so you can turn off the module using any microcontroller pin or switch; a footprint for optional CR1220 coin cell to keep the RTC running (allows for warm-starting); and a tiny bright red LED. The LED blinks at about 1Hz while it's searching for satellites and blinks once every 15 seconds when a fix is found, to conserve power. The FIX output can be used to drive an LED continuously when a location fix is present, or as a logic signal to a microcontroller.
Two features that really stand out about version 3 MTK3339-based module is the external antenna functionality and the the built in data-logging capability. The module has a standard ceramic patch antenna that gives it -165 dB sensitivity, but when you need a bigger antenna, you can snap on any 3V active GPS antenna via the uFL connector. The module will automatically detect the active antenna and switch over! Most GPS antennae use an SMA connector - you might need a uFL to SMA adapter.
We think the datalogging capability is really neat! Once the begin-logging command is sent to the GPS module, any attached microcontroller can be put into sleep mode to conserve power. The time, date, longitude, latitude, and altitude is logged every 15 seconds, and only when there is a fix. The module's internal flash can store about 16 hours of data, it will automatically append data so you don't have to worry about accidentally losing data if power is lost. It is not possible to change what is logged and how often - that's hardcoded into the module - but we found this arrangement covers many of the most common GPS datalogging requirements.
Comes with one fully assembled and tested module, a piece of header you can solder to it for breadboarding, and a CR1220 coin cell holder (coin cell not included). You can pick up a CR1220 coin cell here if you'd like to use the on-board RTC.
Adafruit have a nice fancy library for GPS usage, with background parsing and can set and query the built in GPS logging capability (called LOCUS). A full tutorial is also available, which has tons of information about the module, how to use the data logger and more
- Satellites: 22 tracking, 66 searching
- Patch Antenna Size: 15mm x 15mm x 4mm
- Update rate: 1 to 10 Hz
- Position Accuracy: < 3 meters (all GPS technology has about 3m accuracy)
- Velocity Accuracy: 0.1 meters/s
- Warm/cold start: 34 seconds
- Acquisition sensitivity: -145 dBm
- Tracking sensitivity: -165 dBm
- Maximum Velocity: 515m/s
- Vin range: 3.0-5.5VDC
- MTK3339 Operating current: 25mA tracking, 20 mA current draw during navigation
- Output: NMEA 0183, 9600 baud default
- DGPS/WAAS/EGNOS supported
- FCC E911 compliance and AGPS support (Offline mode : EPO valid up to 14 days )
- Up to 210 PRN channels
- Jammer detection and reduction
- Multi-path detection and compensation