Hi!
First, I'd like to thank everybody for the tips, but they haven't
worked. I formulated a new very simple example to demonstrate the
problem I'm facing.
Suppose I "initialize" a variable in some different and equivalent ways:
char a[10] = {'T', 'T', 'T', 'T', 'T' };
char b[] = "TTTTTTT";
char c[10]; c[0]='T'; c[1]='T'; c[2]='T'; c[3]='T';
//i think this can't be called an initialization!!!
char *d = "TTTTTTT"
now, I perform the test
if ( x[2] == 'T' ) printf("hi"); // x = a, b, c or d
All examples are LEGAL STANDARD PURE C. I chose size 10 and the 3rd
( [2] ! ) element to avoid avoid any doubts that I had enougth space
reserved, and that I took the correct character. All tests should return
true and print "hi". My example ttest.c is to be run on Pc and shows
exactly that with printf's
PROBLEM: when using the very same code on the ATMEGA, changing the
printf's for "turn on led 1", "turn on led 2", etc., only the third char
sequence (C) causes correct evaluation of the if expression (i can see
that, because I have the leds correctly connected and only the 3rd one
lights)
I tryed this under WINDOWS AND UNDER LINUX, using avr-gcc.
Compilation and downloading commands:
avr-gcc -g -mmcu=atmega32 -Wall -o t.o t.c
avr-objcopy -j .text -O ihex t.o t.hex
uisp -dprog=dapa --erase
uisp -dprog=dapa --upload if=t.hex -dno-poll -v=3 --hash=32
------------------------------------------------------------------------
#include <avr/io.h>
#include <string.h>
void xisa() {
// doesn't work
char aux[10] = {'A', 'A', 'A', 'A', 'A'} ;
if ('A' == aux[2]) PORTB |= 0X01; // 1st led
}
void xisb() {
// doesn't work
char aux[] = "BBBBBBB";
if ('B' == aux[2]) PORTB |= 0X02; // 2nd led
}
void xisc() {
// WORKS !!!!
char aux[10];
aux[0] = 'C';
aux[1] = 'C';
aux[2] = 'C';
aux[3] = 'C';
aux[4] = 'C';
aux[0] = '\0';
if ('C' == aux[2]) PORTB |= 0X04; // 3rd led
}
void xisd() {
// doesn't work
char aux[10];
aux[0] = '\0';
strcat(aux, "DDDDDDDD");
if ('D' == aux[2]) PORTB |= 0X08; //4th led
}
void main(){
/***************************************************
* I/O
***************************************************/
outp(0xff,DDRB); // PORT B = OUTPUT
outp(0xff,PORTB); // WRITE PORT
PORTB = 0x00; // BLANKS PORT
// TRY EACH OF THESE COMMANDS ALONE,
// and the problem persists
xisa();
xisb();
xisc();
xisd();
}
------------------------------------------------------------------------
#include <string.h>
#include <stdio.h>
void xisa() {
// doesn't work
char aux[10] = {'A', 'A', 'A', 'A', 'A'} ;
if ('A' == aux[2]) printf("\n1st led");
}
void xisb() {
// doesn't work
char aux[] = "BBBBBBB";
if ('B' == aux[2]) printf("\n2ndt led"); // 2nd led
}
void xisc() {
// WORKS !!!!
char aux[10];
aux[0] = 'C';
aux[1] = 'C';
aux[2] = 'C';
aux[3] = 'C';
aux[4] = 'C';
aux[0] = '\0';
if ('C' == aux[2]) printf("\n3rd led"); // 3rd led
}
void xisd() {
// doesn't work
char aux[10];
aux[0] = '\0';
strcat(aux, "DDDDDDDD");
if ('D' == aux[2]) printf("\n4th led"); //4th led
}
void main(){
/***************************************************
* I/O
***************************************************/
//outp(0xff,DDRB); // PORT B = OUTPUT
//outp(0xff,PORTB); // WRITE PORT
//PORTB = 0x00; // BLANKS PORT
xisa();
xisb();
xisc();
xisd();
}
------------------------------------------------------------------------
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