I have connected a GPS to my WRT54GL 1.1, but have a strange problem with it.

Serial GPS modules are difficult to find (at a reasonable price) where I live, so I followed the instructions that I found at http://www.primianotucci.com/default.php?view=28 and turned a USB GPS to a serial one. As I wasn't sure whether this was going to work I bought the cheapest one (Navibe GM621 with Sony's CXD2951GA chipset)

It seems to run fine on 3.3V and I can get NMEA sentences to my WRT, but for some reason the GPS cannot get a fix, no matter how long I wait. According to the NMEA sentences it sees the satellites, but it doesn't even get the date information, it boots at date 010303 and just increments the time, one second at a time.

The device is working fine, if I solder it back to the USB cable it works just fine. It gets the date information immediately and gets a fix in less than a minute.

I even tried feeding it 5V using 12V from WRT and a regulator, but that doesn't help. I did lower the serial voltage from 5V to 3.3V using a zener in this case.

Anyone else seen this kind of problems? Could it be expecting some input before it really initializes / gets a fix? Something else I should connect or disconnect in the GPS?

TIA

Why are you doing this?  There are LOADS of serial interfaced GPS modules out there. Both of these sites look to ship internationally.  I don't know what you consider to be "cheap" but most of the models on that usglobalsat site of which sparkfun also caries a few look to sell for around $50 or less.

http://www.sparkfun.com/commerce/catego … cPath=4_17
http://www.usglobalsat.com/c-43-engine- … dules.aspx

Thanks for the pointers. I don't have experience with these sites, many of the US sites that I have seen ship internationally only with FedEx / UPS and that makes the delivery usually very expensive. Additionally, local FedEx / UPS offices are eager to handle the customs stuff and charge me a handling fee for it. The final price could easily be over €100 ($160)

That's why I didn't go look for a GPS module at US sites.

I guess I'll try a module like that if I can't make the current one to work. Or then just solder the USB cable back and attach it to my WL-500gp, but I was hoping to use WRT for this, it already has an SD card attached.

I paid €30 (€50) for the USB GPS, I would have happily paid €50 ($80) for a serial GPS module that works with 3.3V.

now I got a fix in serial mode. I used the USB connection, waited for a fix and connected it almost immediately with serial.

let's see if it works also tomorrow, having been without power for some hours.

no, it wasn't actually a fix, it gave the last known location, but had "invalid fix" code in NMEA.

well, if I happen to get it working I'll let you know.