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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Thanks! I've be wanting a gps receiver for some time but cant really afford normal ones.  

Normal? You mean the same ones sold to a much smaller target market.  This is a very good GPS, BTW.

Cold start is middle of the road, but once it is on, it is dead on. The comparison below is to its previous generation sibling, the GPS-360, which is also easy to find at low cost and has the same pinout. The one that disappears (360_2) was a logging problem (I guess I am limited to juggling only 3 :) ) and the crazy stuff from 360_3 was getting a lock. I probably should have let it settle more. the second leg (upper half of the picture) is a truer indication of how they behave once they are locked in. They make a good pair. Look at the destination point at the top. The 500 reports steadier locations when not moving but the 360 would give a robot some chatter to do some "meaningful milling about" until it found the device feeding it coordinates from the 500. 


That is exactly what I mean by "normal ones".  Wow that 500 does seem very consistent. 

Quick question; getting one of these to work would be like getting a "normal one" to work no?  for example em-406a SiRF III Receiver 


Yes. These pictures are of the 360, but the 500 is the same only a smaller total package:


That is connecting to FTDI back to the PC for testing that I soldered properly.

Here is a 500 wired to an Arduino which you can't see, but the wire colors are standard (black is GND, red is VCC, GRN is GPS Tx):


Oh yeah, one more note. Once you have the leads broken out, just use the same leads (by designation, not pin # - GND = GND, VCC = VCC, GPS Tx = GPS Tx) and you can do this tutorial:


Though there are libraries like TinyGPS that make the munging of data much simpler. The main point is that it is just another GPS module.

If you are interested, you probably found it anyway, but...


This won't always be good, of course.

Damn, they don't ship to Canada...

Dam didn't check the shipping...... and of course, they dont ship to Ireland....... 


So they cost a little more, and at the cheapest price do not include the adapter, but are available here:


and that vendor does ship international. US shipping was reasonable. They do also carry the 500 for about $30 + shipping I think.

Also check eBay; people sell Streets from 2006-2008 for a song sometimes and include the GPS.

Pharos 500 is $39.95 plus $21 international mail to Canada. I think I'll ask a friend in the States to get it for me and ship it to me. I'll pay 2 shippings but it is way less than $61. We are so getting ripped off here in Canada...