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Permalink Reply by Lew Payne on June 25, 2010 at 10:14am

You might want to start here. There's even a program you can use to put it in binary mode. Let me know if you need anything else googled for you.

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Permalink Reply by Strix Consili on June 25, 2010 at 4:07pm

I apologize for poor wording (it was early), I meant more along the lines of what does binary mode do, and why is it preferred over the preset NMEA. And no, googling does not clear those questions up.

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Permalink Reply by Ken on June 26, 2010 at 4:07pm

Why? Because binary can carry the same information in fewer bytes (reducing serial data transfer) and in a more "native" format for the CPU which reduces CPU load.

Example:

The SiRF binary position message puts the X, Y, and Z-position (in meters) in 4 bytes each. (A "long int" if you speak programmer.)

In contrast, in the NMEA GGA position message latitude takes 8 or 9 bytes depending on the outputting device and its precision (longitude 9 or 10 bytes) when you include the imbedded decimal point, then to that you add a comma, then a "N", "E","W", or "S". Then there is another comma before the next field. So it takes something like 12 or 13 bytes of NMEA text vs 4 native binary bytes sent through the serial port for the binary format. Then, this NMEA text data has to be converted into a binary format that the CPU can manipulate.

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Permalink Reply by Strix Consili on June 27, 2010 at 9:47am

Ah, exactly what I was getting at. I didn't know exactly what format binary mode meant, but this explains it! Thank you very much for your time.

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