I bought the 10Hz Venus GPS [ http://www.sparkfun.com/commerce/produc … ts_id=9133 ] and antenna [ http://www.sparkfun.com/commerce/produc … cts_id=464 ] back in August but have been a bit busy with other parts of my project to get to it. I did manage to power it up a few times and watched the red NAV LED start blinking when it got a GPS fix. I didn’t have a way to convert the 3.3V TTL logic to 5V for the Arduino at the time, so I was happy with just seeing it get a fix.
Well now I’m ready to actually start working with this thing, but now it refuses to get a satellite fix (NAV LED stays solid). I have Tx/Rx running to the Arduino, and I’ve got 3.3V and ground wired up. One thing I’m unsure of is that VBatt pin. In the comments on the product page, it sounds like Vbatt and VCC are jumped together by Sparkfun, so I’m not sure if I actually need to connect Vbatt to 3.3V (it says to in the SkyTraq common-mistakes page, so I’d like to clarify). At this point I just want to get the thing blinking again so I know it’s tracking like before.
So to those of you out there that have this GPS working, what are some basic things I can do to debug?
Since this module worked before, I’m going to say this is an environmental problem. Are you testing this indoors? I know the module I made is able to get a signal indoors, but the sparkfun module and their suggested antenna will not… or if it does it takes upwards of 25 minutes.
My initial tests back in August were outdoors, but thanks to the snow storms outside, I’ve been sticking the receiver under a window. I figured that would be good enough, but I took your advice and treked outside.
Stuck the receiver on the roof of my car on my way to work this morning for ~25 minutes and it still hadn’t gotten a fix. While I was outside, I tried powering it both with and without the VBatt pin connected to no avail.
Any ideas? Could this thing be fried somehow? Anyone have a definitive yes/no on whether the VBatt pin needs to be connected?
Okay. I hooked just the GPS up to my Arduino and powered it off the 9V battery I’ve been using (which has worked fine for everything else I’ve done thus far). I tested the current draw and was only seeing about 50mA between the 3.3V and GND pins on the Arduino. I remember seeing somewhere that it should be drawing more like 90mA while it’s attempting to acquire a fix.
So, I took the unit back outside to a friend’s car that has a USB port for his stereo and juiced the Arduino that way. About 30 seconds later the light started blinking
I had it running on USB indoors, so both taking it outside and having it properly powered did the trick.
