Hi Rich,


On 25/10/2015 06:39, Richard R. Pope wrote:
> Hello everyone,
>      Well I have it working reliably. Now I can't get my delay routines=20
> to work correctly. No matter what I try my delays do not change.
How you know this? How you measured the real delay?

>  Would=20
> someone look at my delay routines and see if they can spot what I am=20
> doing wrong? Here are the routines:
>
> extern void wait_us(unsigned int delay)
> {
>      for(; delay; delay--)
>      {
>          NOP();      //This is about 500 nS at 1 MHz
Here one error: at 1 MHz of clock the instruction clock is ever 1/4 so 250 =
kHz =3D
4 microseconds.
You can find this explained in paragraph 5.2 of datasheet.


>          //NOP();      //Now we have one uS at 1 MHz
>          //NOP();      //This is about 500 nS at 1 MHz
>          //NOP();      //Now we have one uS at 1 MHz
>          //NOP();      //This is about 500 nS at 1 MHz
>          //NOP();      //Now we have one uS at 1 MHz
>      }
> }
> extern void wait_ms(unsigned int delay)
Here "unsigned int" is 16 bit =3D 0..65535

>      {
>          wait_us(delay * 1000);      //This gives us 1 millisecond
>      }
>
> extern void wait_seconds(unsigned int delay)
>      {
>      wait_ms(delay * 1000);      //This is one second
No! This is an overflow error! 1000*1000 > 65535!
Check your compiler settings, this error can be catched at compile time
(maybe... no experience with XC8).


>      }
>
> Thanks,
> rich!

:-)
      Nic
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