Let's Make Robots!

very cheap GPS

I posted this as a comment on the cheap FTDI cable idea and it occurs to me that a lot of folks who might be interested will miss it there...

My cheap suggestion costs 4 times as much, but includes a free GPS. Currently (Dec 2010) there is a vendor on Amazon selling the Pharos GPS-500 with Microsoft branding (was packaged with Streets) for $19 delivered, including the USB adapter and a USB extension cord. It will come in a plastic case that says Microsoft on it. Carefully crack that open to expose the GPS. Lay it chip down with the connector toward you. The 2nd lead from the left is for 3.3v or 5v (I have had success with both), followed by GND, GPS Tx and GND. Wire those 4 and it will start spewing NMEA strings at 4800 baud. I am pretty sure that GPS Rx is 1st lead on the left. I don't know that it listens for commands, but that would be important if you want to use the USB adapter that came with it to make an FTDI cable. Just match up which would connect to what using the GPS pinouts and you are good to go!

Another poster on that project thread noted that using adapters that make power providing serial cables is not the same as true FTDI.

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I followed your posts about hacking open the gps500 and using it with arduino and it works perfectly. Thanks for the info.

I wanted to also use the usb to ttl cable that came with the microsoft gps. Is there any disadvantage to this cable for programming?

It looks like a 12 pin cable so I assume every 2 pins connect to the pin out on the gps so it wouldn't be too hard to find the pinout and solder on a header socket to the end would it?




Back when I was using that Pharos GPS in a few projects, I bought a Streets package (software and hardware) for about $5 thinking I was getting another Pharos. It turned out to be a Novation 168, which is a one piece unit with the USB on the same board and no edge connectors. So it sat on my shelf a long time. I needed another GPS recently and I decided I needed to either figure out how to use that one or get rid of it. When I put it on the shelf, I figured I would use it on the PC but I really haven't; there just isn't much interesting to do with a GPS on a machine that sits in one place. Anyway, I cracked it open and figured it out.

Yes, I am using it on a PC, but as you can see it isn't plugged in directly with USB; I am using an FTDI cable. After this test, I hot glued it back into the bottom housing and hot glued the wires to the housing on one side for strain relief. Anyway, FTDI provides 5v and sends/receives data at TTL level; if it works on the cable, it will work with the Arduino.