Part 2. Python Application

We'll work through utilizing two python libraries to achieve our goal: pynmea2 and ISStreamer

1. Getting Started

Create or navigate to a directory to store your code:

$ mkdir pi-tracker
$ cd pi-tracker
$ nano app.py

Inside app.py we'll start with the following most basic python:

import serial
import pynmea2

serialStream = serial.Serial("/dev/ttyAMA0", 9600, timeout=0.5)

while True:
	sentence = serialStream.readline()
	if sentence.find('GGA') > 0:
		data = pynmea2.parse(sentence)
		print "{time}: {lat},{lon}".format(time=data.timestamp,lat=data.latitude,lon=data.longitude)

2. Code Explanation

1. imports

Importing the serial and pynmea2 modules

import serial
import pynmea2

2. serial factory

Creating a serial stream on UART at /dev/ttyAMA0 at 9600 baudrate with a timeout of 0.5 seconds.

serialStream = serial.Serial("/dev/ttyAMA0", 9600, timeout=0.5)

3. read from serial

Read the NMEA sentence from serial, parse and check to see if it's a GPGGA sentence (which means it will have coordinate data in it), and print the data to the screen.

while True:
	sentence = serialStream.readline()
	if sentence.find('GGA') > 0:
		data = pynmea2.parse(sentence)
		print "{time}: {lat},{lon}".format(time=data.timestamp,lat=data.latitude,lon=data.longitude)

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