Help with Adafruit Ultimate GPS breakout.
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Help with Adafruit Ultimate GPS breakout.

by mattcy on Thu May 09, 2013 5:46 pm

Hello.

I need to increase the update rate of the ultimate GPS breakout from the rPi. I have it working successfully at the default 1Hz just fine but have been unable to successfully change the update rate.

I am currently using it via the usb connection explained in the tutorial. But I could move it to GPIO is need be.

Please help and thank you in advance.
mattcy
 
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Re: Help with Adafruit Ultimate GPS breakout.

by adafruit_support_rick on Thu May 09, 2013 6:20 pm

Here are the update rate sentences we have defined in the arduino library:
Code: Select all | TOGGLE FULL SIZE
// different commands to set the update rate from once a second (1 Hz) to 10 times a second (10Hz)
#define PMTK_SET_NMEA_UPDATE_01HZ  "$PMTK220,10000*2F"
#define PMTK_SET_NMEA_UPDATE_1HZ  "$PMTK220,1000*1F"
#define PMTK_SET_NMEA_UPDATE_5HZ  "$PMTK220,200*2C"
#define PMTK_SET_NMEA_UPDATE_10HZ "$PMTK220,100*2F"

So, if you wanted to switch to 5Hz, you would send the command string $PMTK220,200*2C to the GPS.

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Re: Help with Adafruit Ultimate GPS breakout.

by mattcy on Thu May 09, 2013 9:47 pm

Thanks for the info. I tried sending the command via python using the code snippet below:
Code: Select all | TOGGLE FULL SIZE
 import serial
s = serial.Serial(port='/dev/ttyUSB0', baudrate=9600)
s.write('$PMTK220,200*2C')


I didn't receive any errors, but data is still coming in at 1 second intervals.

I'm not dedicated to setting via Python, its just something I'm more familiar with, if there is a better way (shell script, putty, etc.) I'm open to any input.

Again thank you for the help.
mattcy
 
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Joined: Thu Mar 28, 2013 12:38 pm

Re: Help with Adafruit Ultimate GPS breakout.

by adafruit_support_rick on Fri May 10, 2013 11:28 am

If you post your code, we'll see if we can spot the problem

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Re: Help with Adafruit Ultimate GPS breakout.

by mattcy on Sat May 11, 2013 5:57 pm

I was able to resolve my problem. It turns out that you can't set the update rate to 5Hz or 10 Hz (I suspect anything > 1Hz) unless you update the baud rate. Before updating the baud rate I was receiving ACK message back saying command "understood but failed" Once I increased the baud rate to 38400 I can set the update rate to 10Hz successfully.
mattcy
 
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Joined: Thu Mar 28, 2013 12:38 pm

Re: Help with Adafruit Ultimate GPS breakout.

by adafruit_support_rick on Sat May 11, 2013 6:04 pm

Ah, yes. Glad you figured it out! :D

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