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).
To connect the two boards requires four wires.
GND -> GND
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.