[avr-gcc-list] Re: global variables - II

[Stein Haaland]

My problem is not really connected to the EEPROM writing, more
to the definition of global variables, thus the subject.

The code snippet below illustrates the problem. The Port 
(on a STK 500) does not sequentially output the character 
string as expected; it rather toggles between 0x00 and 0xFF. 

I can set the port to any value, using local variables.
Is there anything I have misunderstood in the use of global 
variables and avr-gcc ?

----
#  include <avr/io.h>

char text[] = "This is a test";    // test string or uint8 array or...


void wait(uint16_t ms)
{
 ...
 // a multiple do while loop to create a delay. Works !
}


void write_text_to_port() 
{
  uint8_t i;
  
  for (i=0; i<10; i++) {
    PORTB = ~text[i];            // Port B = character[i]
    wait(400);                   // ...wait....
    PORTB = ~0x00;               // turn of all leds
    wait(400);                   // ... wait ...
  }
}


int main(void)
{
  DDRB = 0xFF;                   // set to output

  write_text_to_port();
}

---


> ...
> Your character matrix is very large. Isn't it in fact 
> larger than the available amount of SRAM in AT90S8515????
> ..
>/Mikael Krus

Yes, thanks for pointing out. This is a side issue though.

>..
>Is DDRC == 0xFF ? 

Yes, DDR is set. 

> If you want to store data in the EEPROM once, you could also build 
> a Intel Hex File ... 
> Bernard 

This is my intention - any examples references on how to do this ?


(Sys :
MDK Linux 10.0.
avr-gcc (GCC) 3.3.2 
objcopy 2.14 20030612
uisp version 20040311
STK500 testboard, AT90S8515)

SEH.