GPS Differing Sentences

[lucgallant]

Hi there,

I have a question about the GPS shield/module.

Up until yesterday my GPS shield was working well, it was giving me correct date and time. However, at some point, it started giving me the correct time, but giving me the date of December 30, 1999. It appears from looking at the sentences that the date is not being returned.

I turned on GPSECHO, and this is what I see in the raw sentences:

$PGTOP,11,2*6E
$GPGGA,005259.000,5644.3243,N,11127.7569,W,1,07,1.26,347.2,M,-26.3,M,,*53
$GPRMC,005259.000,A,5644.324N12.76W.81.7,04,*C


If I change the sendCommand to only receive RMC, and not RMCGGA, this is what my sentences look like:

$PGTOP,11,2*6E
$GPRMC,004217.000,A,5644.3310,N,11127.7633,W,0.01,279.51,250914,,,A*79

So the date is there if I only do RMC.

If I run the "Parse" example sketch, everything works. I checked for bad checksums, but it appears I'm not getting a bad checksum.

I also checked for memory issues, doesn't appear to be any, I've got plenty of memory left.

Any ideas?

UPDATE: I had tried making Timer1 interrupt every millisecond, so that I can leave the millis() interrupt alone and make my time more accurate (per my other post). Apparently that's my issue? If I make that timer period 100 ms instead, I'm getting all the data I need. I think I'm continuously overestimating the capabilities of the Arduino... Any feedback would be great.

[adafruit_support_rick]

You're clearly dropping characters in the GGA/RMC sentences you posted. But it sounds like you've found that problem?

[lucgallant]

Well, yes, seems like I solved the problem.

The Arduino must have been over taxed by having two interrupts fire every 1 ms. After I disabled the Timer1 interrupt and put the GPS code back in Timer0, I stopped losing characters... I would have thought it could handle it, but I guess I was wrong.

All good. Thanks.