Ultimate GPS Breakout not accepting commands
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Ultimate GPS Breakout not accepting commands

by landis on Tue May 29, 2012 12:43 am

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
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Re: Ultimate GPS Breakout not accepting commands

by adafruit on Tue May 29, 2012 1:56 pm

post up a pics your wiring, make sure you have the RX pin connected properly of course!
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Re: Ultimate GPS Breakout not accepting commands

by landis on Wed May 30, 2012 9:22 pm

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.

Image

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?
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Re: Ultimate GPS Breakout not accepting commands

by adafruit on Wed May 30, 2012 10:00 pm

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
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Re: Ultimate GPS Breakout not accepting commands

by zeptosecond on Wed May 30, 2012 11:36 pm

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.
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Re: Ultimate GPS Breakout not accepting commands

by adafruit on Thu May 31, 2012 8:24 am

zeptosecond wrote: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
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Re: Ultimate GPS Breakout not accepting commands

by zeptosecond on Thu May 31, 2012 12:27 pm

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.
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Re: Ultimate GPS Breakout not accepting commands

by adafruit on Thu May 31, 2012 2:37 pm

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
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Re: Ultimate GPS Breakout not accepting commands

by landis on Thu May 31, 2012 4:08 pm

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?

Image
Pic taken with my USB Microscope that came today, w00t!
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Re: Ultimate GPS Breakout not accepting commands

by adafruit on Fri Jun 01, 2012 9:11 pm

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!
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Re: Ultimate GPS Breakout not accepting commands

by landis on Mon Jun 11, 2012 10:30 pm

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 :(
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Re: Ultimate GPS Breakout not accepting commands

by adafruit on Tue Jun 12, 2012 10:34 am

what did you do with the software???
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Re: Ultimate GPS Breakout not accepting commands

by landis on Tue Jun 12, 2012 11:05 am

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.
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Re: Ultimate GPS Breakout not accepting commands

by adafruit on Wed Jun 13, 2012 3:12 pm

Thats -really- odd. Even restarting the software doesn't fix things?
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Re: Ultimate GPS Breakout not accepting commands

by landis on Fri Jun 15, 2012 7:51 am

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