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Re: [avr-gcc-list] General programming question/GPS parsing


From: Bernard Fouché
Subject: Re: [avr-gcc-list] General programming question/GPS parsing
Date: Wed, 02 Mar 2005 09:55:06 +0100
User-agent: Mozilla Thunderbird 1.0 (Windows/20041206)

wbounce a écrit :

I am think of trying to parse a GPS feed which is transmitted at 4800
baud. It can send 7 "sentences" of a max of 80 bytes to a potential of
560 bytes every second. Then I need to parse the data. I am concerned
about how much time and ram it will take to do all of this. With only 4K
of ram space how would you handle this. I was think of using a round
robin buffer approach but then that complicates the parsing with having
to worry about wrapping. Or should the program be fast enough to process
the 1st 80 bytes by the time the 2nd sentences is done coming in? I am
running a ATMega 128  16MHZ. Using WinAvr C and was think of using the
AVRlib  standard strcmp,strsep,strtok_r etc.


Has anyone done this and kept control of a robot at the same time?

Are there timing values for the library routines?
Here we are parsing GPS strings at 9600bps with atmega64/128 clocking at 1.9Mhz and the program does much more than only GPS string parsing. So at 16Mhz you don't have any performance problem. Just use interrupt driven routine not to lose time polling something that keeps the cpu busy waiting.

 Bernard




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