|Do you know where your variables are?|
GPS tracking with Perlby stevieb (Abbot)
|on May 17, 2017 at 00:56 UTC||Need Help??|
I finally got my little GPS unit for my Raspberry Pi, which cost me $50 CDN. It connects via the Rx and Tx pins of the serial interface. My new GPSD::Parse module (may not have indexed yet) is not Pi specific though. Any serial connected GPS device will work (even USB ones).
There aren't any non-core modules in use so it's exceptionally lightweight. The only requirement is to have gpsd daemon installed and running. I run it like this: sudo gpsd /dev/ttyS0 -n -F /var/log/gpsd.sock at startup.
Note that there is a much more extensive distribution Net::GPSD3 that does the same sort of thing, but I had a nightmare trying to install it with a whole long chain of dependencies, and it was a little confusing to use. I wrote this one for simplicity. All tests effectively skip until the next version, when I re-implement a test regime that uses a data file as the input instead of a network socket, which most may not have running. I also have immediate plans for new features, but I just wanted to get it up after 100% test coverage (locally) and 100% POD coverage so that I can see what it looks like on the CPAN.
I've put together a tiny demo of some basic output below, but the information that can be extracted is quite extensive. The documentation explains all of the various attributes and how to get at them. It even shows how to extract the entire raw JSON data returned from the device, or that raw data after it's been converted into a Perl data structure.
Tiny example. Of course in the real world, you'd put something like this in a loop, polling every second or whatever. Note that I've obfuscated the coordinates a tiny bit, but they are accurate right to my front door, literally:
I've also got this working in C on my Arduino Trinket Pro, which I'm going to use to make a hiking GPS so I can track my movements in the field.
Here's the output. The altitude defaults to metres.
Here's a list of items you can fetch in regards to the TPV (Time Position Velocity):
...and information you can gather about the satellites you can see (using the satellites() method). Currently, after having the unit on for about 24 hours, I'm 'using' nine in total to pinpoint me: