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Figure 2 - The SanJose FV-M8 from SparkFun is a fully functional GPS in a tiny box
Figure 2 - The SanJose FV-M8 from SparkFun is a fully functional GPS in a tiny box

GPS receiver modules have come a long way over the last few years. The tiny 1 inch square FV-M8 receiver module form San Jose Navigation is ready to use as soon as power is supplied. Once powered up, the GPS module will search for satellites and then send a 1 Hz "heartbeat" pulse down one of the IO lines to show that it has a valid fix. The module will also send out serial data containing all of the relevant GPS information so that a microcontroller or terminal can decode the data. So, to add GPS capabilities to your project, you really only need three wires: one for power (3.3 volts), one for ground, and one to receive the serial data! A few years ago, I tried to add GPS capabilities to a robot project using a much earlier GPS module, and failed after wasting a week trying to decode the data sheet. Nowadays, things are much easier.

Most GPS modules can also be configured via serial communications, but unless you need to change the default settings, the modules can be used without any prior setup or configuration. Serial communication speed, data transmit rate, and data format are some of the more common configurations that can be changed in most GPS receivers, but for this project I will simply work with the default settings as indicated in the datasheet for the GPS module.



Figure 3 - The datasheet will detail the IO lines as well as default settings
Figure 3 - The datasheet will detail the IO lines as well as default settings

The first step in connecting a GPS module is to supply the needed voltage and then connect the receiver and possibly the transmit line to your microcontroller. The data sheet will show you the pinout of the GPS connector, as well as all of the timing and communications parameters that are needed. If you are planning to use a development board that will accept the connector for your GPS module, then the IO pin configuration is not important at this time, but eventually you will probably want to reduce your project down to just the GPS module and a microcontroller. Figure 3 shows the section of my datasheet that indicates the purpose of all eight wires coming out of the GPS module. Out of the eight possible wires, I only needed three of them to get the data into my microcontroller: power (VIN), ground (GND), and transmit (TX1).

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