XC8 编译器无法识别 __delay 宏

Question

I want to program a ATtiny85 microcontroller and have realized that my program needs a bit of delay to work properly. I am using MPLabX and the XC8 compiler. So I should be able to use the __delay_ms() macro and MPLab does recognize the macro and does NOT put the red line under the code. However when I try to compile the programm, there is an error thrown at each line where I use the macro. "Undefined reference to __delay_ms" And also an additional "implicit declaration of __delay_ms" for the first line that uses the macro. I do have _XTAL_FREQ defined correctly and xc.h included.

The code also compiles just fine without the delay macros, but than it doesn't work correctly, so I need the delay.

I don't know what the problem is. I have programmed other microcontrollers with the __delay_ms macro before. I am also using the latest version of the XC8 compiler. And according to the documentation of the compiler the version is fully compatible with the ATtiny85.

I also tried to find a solution on the internet, but didn't find anything that helped with my problem...

Any ideas where the problem could be?

Answer 1

So I did some more digging in the include directories for xc8 and I found something. If I include util/delay.h I can use the functions, but only using one underscore instead of two. So the command has to be _delay_ms(). Then I can compile the code, but it is missing a definition for F_CPU. This however only results in a warning and not an error. I will try to find out where F_CPU is defined. I am guessing it is defined relative to _XTAL_FREQ somewhere...

I will keep you updated on what I can find out.

Answer 2

Maybe this should be a comment, but I want to give you an example which compiles fine for me:

This is the way it works for a PIC

compiler: xc8 2.0

#include <xc.h>
#define _XTAL_FREQ   4000000

void main (void)
{
    while(1)
    {
        __delay_ms(1);
    }
}

For an AVR it's a little bit different: (thats's crazy!)

#define F_CPU 4000000UL
#include <xc.h>
#include <avr/delay.h>
    
int main(void)
{
    while (1)
    {
        _delay_ms(1);
    }
 }

Answer 3

And.. Microchip has changed things again with AVR.. This is with MPLABX 5.5 and XC8 2.32.

    #define F_CPU 4000000UL
    #include <xc.h>
    #include <util/delay.h>  // change to util from avr
    
    int main(void)
    {
        while (1)
        {
            _delay_ms(1);
        }
     }
`