GPS.wakeup() hangs

[kirasglimmer]

It looks like the v3 GPS module wakeup method isn't working correctly. The data sheet says to send an arbitrary byte to the module to take it out of sleep mode. The Adafruit library is doing that but is also waiting for a response message. I don't believe the GPS module sends a response when coming out of sleep mode. Can you verify?

[barbudor]

Shouldn't the module starts to send NMEA sentences right after wakeup ?

[kirasglimmer]

That's true, however the behavior I was observing is this: status light would blink as expected (I don't get a GPS fix in my workshop). Invoking the sleep method would obviously sleep the module (no more status blinks or serial data). After a 5 second delay, the test code would invoke the wakeup() method. The GPS module fix light would come on and stay on and I'd get no further response from the module - no serial data from the Arduino. Once I called GPS.sendCommand("") it woke up just fine and resumed it's "normal" behavior. Weird.

[tdicola]

Hrm, I couldn't repro this issue with a V3 module. I modified the echo example setup() function to print data for 5 seconds, then sleep for 5 seconds, and finally wake up. The module appears to function as expected with data being echoed for 5 seconds, going to sleep and no data being echoed for 5 seconds, then waking up and data being echoed again.

Here's what I added at the end of the setup function:

  delay(5000);

  Serial.println("Going to sleep!");
  GPS.standby();

  delay(5000);

  Serial.println("Waking up!");
  GPS.wakeup();

Example of the output:

...
$PGTOP,11,2*6E
$GPGGA,192408.000,4740.8018,N,12211.9873,W,1,6,1.80,30.0,M,-17.2,M,,*5F
$GPRMC,192408.000,A,4740.8018,N,12211.9873,W,0.58,53.52,070814,,,A*4E
$PGTOP,11,2*6E
$GPGGA,192409.000,4740.8017,N,12211.9870,W,1,6,1.80,30.0,M,-17.2,M,,*52
$GPRMC,192409.000,A,4740.8017,N,12211.9870,W,0.57,53.52,070814,,,A*4C
Going to sleep!
$PMTK001,161,3*36
Waking up!
$PMTK010,001*2E
$PMTK010,002*2D
$PGTOP,11,2*6E
$PGTOP,11,2*6E
$GPGGA,192415.840,,,,,0,0,,,M,,M,,*4E
$GPRMC,192415.840,V,,,,,0.00,0.00,070814,,,N*41
$PGTOP,11,2*6E
$GPGGA,192416.840,,,,,0,1,,,M,,M,,*4C
$GPRMC,192416.840,V,,,,,0.12,0.00,070814,,,N*41
$PGTOP,11,2*6E
$GPGGA,192417.840,,,,,0,1,,,M,,M,,*4D
$GPRMC,192417.840,V,,,,,0.16,0.00,070814,,,N*44
...

I'll close this for now, but let me know if you find other things to try reproducing. Thanks for raising the issue!