Ultimate GPS Breakout not accepting commands

[landis]

I recently purchased the Ultimate GPS Breakout (MTK3339). At first, I was able to start LOCUS using the example sketches, as well as change the update frequency or data output using the commands in the library (GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCONLY))...

Lately I haven't been able to access anything using the commands. The only output from the unit is what appears to be "all output", at 1Hz. Trying to start or query LOCUS status always yields the "No Response ".

Any thoughts on why I no longer have access to the more advanced features of the GPS?

Further details:
tested indoors near window, and outdoors. LED will blink once a second, then gets a fix and goes to once/10 or so seconds. Data that comes out of serial once fix is established looks like good GPS data, UTC timestamp is correct, and GPS coordinates are correct. I just can't adjust the output or start LOCUS.

Thanks,
Jim

[adafruit]

post up a pics your wiring, make sure you have the RX pin connected properly of course!

[landis]

From the arduino to the gps:
5V -> VIN
GND -> GND
D2 -> RX
D3 -> TX

Basically, pretty simple hookup. The GPS strings are correct, if you need the raw output from the unit as well, I can take it outside with a laptop and capture.



My working theory so far is that the GPS unit might be fine, but the micro-controller where the flash memory would be is not working.
Also, to rule out any problems with the UNO, I also tried a MEGA2560 board I have, with same results, and I was able to use the arduino with a 16x2 screen using those 2 pins successfully, so I'm 98% sure the arduino is OK.

EDIT
Sorry for the huge picture! Any way to set picture sizes on a img link?

[adafruit]

lets try one more thing - can you double-down on the soldered header for the GPS unit? just go over it and give it more solder and make sure it flows well
if that doesnt fix it, email support@adafruit and ask for a new one

[zeptosecond]

I'm having the exact same problem. I think my problem started after I changed the baud rate. I'm have been fighting this for hours and could use any help that can be offered.

[adafruit]

I'm having the exact same problem. I think my problem started after I changed the baud rate. I'm have been fighting this for hours and could use any help that can be offered.

use the blank sketch and connect via the GPS tool - dont change the baud rate! keep it at 9600, the arduino cant use software serial at higher rates very well

[zeptosecond]

I changed the baud rate because it was dropping characters. Any ideas as to why that would happen?

I'm on a mac so I'll have to find a PC to run the GPS tool on.

[adafruit]

zepto, get it back to 9600 and post a new thread, we're trying to help a customer in this one and its confusing to have two posters with different problems

[landis]

No luck with the double-down, same symptoms. Also checked the voltage out on the 3.3 pin, getting 3.325V, so problem does not seem to be with the voltage regulator.
Think I got a bad unit?


Pic taken with my USB Microscope that came today, w00t!

[adafruit]

landis, nice work there but lets replace your GPS - email support@adafruit and hopefully that will solve it. we do test the RX pin so not sure what could have happened!

[landis]

Follow up to issue above using new unit.

Now this unit is not working either, and I know exactly when it happens. DO NOT use the MT3339 GPS PC Tool software linked to at the bottom of the tutorial on ladyada.net. My replacement unit is now bricked as well

[adafruit]

what did you do with the software???

[landis]

I was trying tonread the LOCUS memory. On the LOCUS tab, when I pushed the "query" button, it locked the gps up. Now it wont respond to any of the commands.

[adafruit]

Thats -really- odd. Even restarting the software doesn't fix things?

[landis]

Yup, restarting the software has no effect. Also resetting the arduino, reloading sketches... I'm at a loss.