Help Needed Keil and Atmel 89s8253

[nrmlguru]

Hello,

I wrote the following code to toggle the PORT0 of AT89S8253. I dont want to use the header files available for AT89S8253.

#define PORT0 (*((volatile unsigned char*)(0x80))) /* P0 @ 0x80 */

void main()
{
unsigned int i;

while(1)
{
for(i=1000; i>0; i--);
PORT0 = 0xFF;
for(i=1000; i>0; i--);
PORT0 = 0x00;
}
}

I dont see the toggling. I see 0xFF all the time at address 0x80.

 

[kandhu26]

Increase the delay and check it... For 8051 series if u use 8 MHz crystal... Write a delay fuction like,
void Delay(unsigned int time)
{
while(time--);
}

then in main function call Delay(30000); Before making high and before making low.... This is approximately almost 1 sec delay... Or better u go with timer delay....

 

[nrmlguru]

Hello kandhu26,

Thanks for the answer. But I am checking the location in debug mode and i am doing single stepping. Delay should not matter.