GPS on the table
Another update for my linux powered autonomous car project :)
After I successfully björked the USB and bluetooth connections for the gumstix motherboard with one config file write, I’ve had no way to connect to the gumstix motherboard. I bought a few of the 60 pin headers to try to make my own breakout board, but realized quickly that unless there is a custom-made PCB to go along with it, it was an effort in vain.
Meanwhile, the GPSStix boards were back in stock at the ‘ol gumstix warehouse, so I snatched one of those up as quickly as I could. I also bought a few more toys from Acroname (which I’ll get into later) but most importantly a TTL level RS-232 to USB adapter, as well as an active GPS antenna from Spark Fun Electronics for just $14.
Phew, what a mess of wires this is going to be!
The USB adapter lets me connect the FFUART of the Verdex to my macbook pro. This is crucial because the motherboard uses this UART as the default linux console when all else fails (or is messed up due to my linux n00bness). Put it together with a wire-wrapping tool, and it will come out something like this:
Needless to say it took a while, but I got everything working before midnight last night, as well as a shell script to log the GPS coordinates of wherever you are. Plugging these into google maps (because I’m so sophisticated) the GPS unit was accurate to within several feet, inside. I’m going to do some more testing, but it looks like it’s going to be about perfect!
There’s nothing like loggin in via SSH over a bluetooth connection to a linux box the size of a stick of gum (that’s powered with my cell phone charger :P).
*** Update ***
I whipped up a shellscript to take a GPS coordinate every 30 seconds and log it to a text file. I put it all in my backpack on the way home from work, and logged my journey home to Oakland from the Six Apart office in San Francisco. If you have Google Earth, you can follow my journey from a KML File I created.
Note the jaggedy (?) edges at some points; this is because I was only capturing every 30 seconds. Also, you can see when I went in the tunnel under the bay because I didn’t get any readings until I popped up on the other side. I might do the same thing on the way to Chico on Amtrak tomorrow, and have been contemplating taking it up with me to Mt. Shasta when I climb it this weekend. :)
From what it looks like, it is getting between 1 and 3 meter accuracy, 5 at some points. Again, this is perfect! I can’t wait to get going with the software for this thing.
Before I go, I’m going to leave you with a video of the commercial we helped shoot in roseville a couple weeks ago:
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