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Re: [avr-gcc-list] GCC Functions

From: Joerg Wunsch
Subject: Re: [avr-gcc-list] GCC Functions
Date: Tue, 27 Nov 2001 10:59:52 +0100 (MET)

Patrick Lanphier <address@hidden> wrote:

> void led1(void);
> int ledlight;
> int main(void) {
>   outp(0xff, DDRB);           // port B all outputs
>   outp(0xff, PORTB);          // turn all leds off
>   led1();

What happens if you don't call led1(), but just continue?

>   for(;;){
>     outp(ledlight, PORTB);        // turn led on
>   }
> }
> void led1(void){
>   ledlight = 0x0;
> };

This is basically a do-nothing, since ledlight is already 0x0 (per
definition, since it's a global variable).

I can't see anything that would be wrong with the code though.

What would be more interesting is:

void led1(void) {
  ledlight ^= 0xff;

  for (;;) {
    outp(ledlight, PORTB);

This should make all pins on Port B oscillate with the same frequency.
Alternatively, make led1() count ledlight up:

void led1(void) {

This should make all pins oscillate with frequencies divided by 2

J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/

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