Delay_us() and Delay_ms() only take constant parameters

[brelstad]

It would be most convenient if the
Delay_us() and Delay_ms() routines could take variables, not just constant expressions.

Bengt

[nemanja.nikolic]

Hello,

You can use delay routines with variables, you can use following function:

Code: Select all

unsignedpause = 1000;
...
Vdelay_ms(pause);  // ~ one second pause

Look at help.

Nemanja.

Best regards.

[brelstad]

Hi, I tried this:

procedure TestDelay1(const sTestDelay: dword);
begin
Delay_us(sTestDelay);
end;

procedure TestDelay2;
var zTestDelay: dword;
begin
zTestDelay := 1000;
Delay_us(zTestDelay);
end;

Both procedures fail to compile and the compiler message is:
Syntax error: Expected "constant expression" but "complex expression" found

[nemanja.nikolic]

Hello,

You can't use Delay_ms() with variables.
Look at simple example:

Code: Select all

program Vdelay;

var cnt: word;

begin
  cnt := 1;
  while TRUE do
    begin
      cnt := cnt + 1;
      Vdelay_ms(cnt);
    end;
end.

Nemanja.

Best regards.

[brelstad]

Yes, finally we agree

If you read my first post, you will see that this is exactly my point.
Delay_us() and Delay_ms() can only take constant expressions, not variables.
Which is my reason for writing this post here in the wish list.

It would be most convenient if the Delay_us() and Delay_ms() routines could take variables, not just constant expressions.

Could you please pass this on to the developers?


Thanks,
Bengt

[nemanja.nikolic]

Hello,

Because of that we have another routine for variable: Vdelay_ms();

Nemanja.

Best regards.

[brelstad]

Ah, thanks, that certainly helps for millisecond delays.

Then my wish for the future is a delay routine for variables, that takes microsecond delays.

Thanks,
Bengt

[nemanja.nikolic]

Hello,

For microsecond would not be so exact.
You can create function for that if you haven't much values and if your values isn't too small (more larger then 1/Fosc).
For example:

Code: Select all

procedure Delay_VAR(VAR : word);
  case VAR of
     1: begin
	      Delay_us(100);
		end;
	 2:	begin
          Delay_us(200);
        end;
	 3: begin
          Delay_us(300);
        end;
           .		
		   .
		   .
		   .		   
  end;
end;

Nemanja.

Best regards.

[corado]

Why it is made with constand and not Var?
Where is the benefit?
Why not only the delay Version with Variable?
Are the Nachteile Disadvantages?

[IvanJeremic]

Hi,

Because there were precision issues when using variables instead of constants.

Regards,

Ivan.