GPS and Raspberry Pi

I ordered a 56 Channel GPS Receiver (GP-20U7) from hobbytronics. The GPS is made by SparkFun, its tiny as you can see below. So far it is working well and was easy to get working.

Cable things up

I guessed the pinout from the datasheet. Nothing exploded.

RPI -- GPS
GND -> GND
RX  -> TX
3V  -> VCC

Unbind serial

The RPI comes with the serial pins bound to a TTY terminal. This lets you plug it into a USB-TTL cable and use screen to control the PI. To use the PI with a device that uses serial to talk you need to unbind it first.

• Remove console=ttyAMA0,115200 from /boot/cmdline.txt
• Remove T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100 from /etc/inittab
• Reboot.

Test and go

Check its working with screen, you’ll see the raw NMEA-0183 protocol:

sudo screen /dev/ttyAMA0 9600

Install and start gpsd:

sudo apt-get install gpsd gpsd-clients 
sudo gpsd /dev/ttyAMA0 -F /var/run/gpsd.sock

Use either cgps -s for CLI, or xgps for a GUI.

It took a good 15min for the first boot to get all the data. This is normal. After it was able to keep a solid lock inside next to a window.

12 Jan 2016