SparkFun GPS Breakout (ZOE-M8Q and SAM-M8Q) Hookup Guide
Elias The Sparkiest 
Which GNSS Unit Do I Pick?!
Size and GNSS Antenna
In each of the following Hardware Overview sections we'll layout the characteristics of the GNSS boards. Let's begin with the more obvious differences between the boards. The SAM-M8Q is a larger board with dimensions of 1.6 x 1.6 inches. The relative larger size of the board helps to enhance the product's GNSS antenna that houses the GPS unit inside. The ZOE-M8Q is 1 x 1 inch board that does not have an onboard GNSS antenna, and instead has a U.FL connector to connect to an external one. This gives you the option to use something that can be attached outside while the GPS unit is inside connected to your microcontroller.
GNSS Capability Comparison
The SAM-M8Q and ZOE-M8Q GNSS receivers both utilize the 72-channel u-blox M8 engine; therefore, their capabilities are so similar that the differences are negligible. The one major difference between them is that the SAM-M8Q does not connect to the Chinese BeiDou GNSS constellation.
| GPS + GLONASS | GPS | GLONASS | Galileo | BeiDou | ||
|---|---|---|---|---|---|---|
| Horizontal Position Accuracy | 2.5m | 2.5m | 4m | 3m | 3m | |
| Max Navigation Update Rate | 10Hz | 18Hz | 18Hz | 18Hz | 18Hz | |
| Time-To-First-Fix | Cold Start | 26s | 29s | 30s | 45s | 34s |
| Hot Start | 1s | 1s | 1s | 1s | 1s | |
| GPS + GLONASS | GPS | GLONASS | Galileo | |||
|---|---|---|---|---|---|---|
| Horizontal Position Accuracy | 2.5m | 2.5m | 8m | TBD | N/A | |
| Max Navigation Update Rate | 10Hz | 18Hz | 18Hz | 18Hz | N/A | |
| Time-To-First-Fix | Cold Start | 26s | 29s | 30s | TBD | N/A |
| Hot Start | 1s | 1s | 1s | TBD | N/A | |
SPI Interface
Both GNSS receivers support I2C and serial communication to receive your NMEA data. However, the ZOE-M8Q also supports a SPI interface. The SPI interface can be enabled by closing the SPI jumper on the bottom of the board.
