Connecting the GPS receiver to a PC

My long term goal is to connect the GPS receivers to battery powered low cost single board computers, probably Raspberry Pi, to make them stand-alone.  For now, though, I am connecting them to my Windows laptop for simplicity.  The Ublox receiver board interface is a UART which can be directly connected to the Raspberry PI, but to connect to the PC we need to first convert the UART signals to USB.  I am using a USB to UART converter board from Sparkfun.  There are many similar boards available, I use this one because Sparkfun happens to be a few miles from my house.  If I place an order in the morning, I can pick it up in the afternoon, which is very convenient (and avoids any shipping charges).

SparkFun FTDI Basic Breakout - 5V
USB to UART converter board from Sparkfun


SparkFun FTDI Basic Breakout - 5V
Back of board











USB to UART converter board connected to GPS receiver (and antenna)



To connect the two boards requires four wires.

RX -> TX
TX -> RX

You can’t see in the photo, but I soldered the connecting wires directly to the receiver board and the other ends to a four pin header which I then plugged into the connector on the back of the UART converter board (see connector in the photo above).

The board can now be connected to the PC with a USB cable, making sure you have the right connector for the UART board you are using, in this case, a mini-USB connector for the Sparkfun board.

Note on voltage levels:  USB/UART converter boards come in various combinations of 3.3V and 5V levels for Vcc and I/O.  Make sure you pay attention to the voltage levels when you select a converter board or cable.  The Vcc input on the GPS board is fed into a voltage regulator so Vcc can be either 3.3V or 5V.  RX and TX, however, are connected directly to the M8N chip and must be 3.3V.

I originally used a 5V version of the Sparkfun board and it worked fine for months but eventually I was not able to transmit commands to the receiver any more although everything else seemed to work fine.


In the next post, I will cover using the Ublox eval software to talk to and configure the receiver before we start using RTKLIB.


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