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[avr-libc-dev] newbie question on avr-lib and stk500

From: Rainer Faulstich
Subject: [avr-libc-dev] newbie question on avr-lib and stk500
Date: Thu, 22 May 2003 10:16:27 +0200

i am a beginner with avr, writing code for atmega128 using avr-gcc and avr-lib 
and testing with stk500/501 i/o LEDs.
I modified the example "basic_io" provided with avr-lib a bit and connected the 
STK500 LED Header to the PORTB header.

// snipp.....................
  unsigned char a;
  outb(DDRB, 0xFF); // set all port B pins to output
  outb(PORTB, 0xFF); // switching all LEDs OFF
  outb(PORTB, a);

  //...................... snipp

This piece of code does not show the expected result 00111100 but gives 
10000000. If i use the last line as "outb(PORTB, 0x3C)" omitting the variable a 
the result is as expected.
My question: where is the RAM area located ? Are there any macros in avr-lib 
where i can change it. I suspect that the variable is not available.

Regards Rainer 

Rainer Faulstich
Ingenieurb?ro f?r Prozessautomatisierung, ifp
Friedrich Werber Str. 44

D-78315 Radolfzell
Tel: (+49) 7732 98 27 89 - 12
Fax: (+49) 7732 98 27 89 - 44

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