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Hi~

I am new in BX24, my problem is shown below

Do
call control()        'a control function
delay(2.5e-4)
loop

I want the loop's freq is 4000Hz, but the min. time of delay
should be 1.95ms, so is that loop work? or any other suggestion?

Tahnks a lot
Owen
	

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FYI - If you have a time delay of 1.95ms then max loop freq is aprox. 
500 hz or less.

You should also consider the time of the called functions in your 
loop when calculating your total loop time, not just the delay 
function.

What frequency did you get when you tried it out?

rr

--- In basicx@basi..., letter2email@... wrote:
>
> Hi~
> 
> I am new in BX24, my problem is shown below
> 
> Do
> call control()        'a control function
> delay(2.5e-4)
> loop
> 
> I want the loop's freq is 4000Hz, but the min. time of delay
> should be 1.95ms, so is that loop work? or any other suggestion?
> 
> Tahnks a lot
> Owen
>
	

(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

I have tried the following method to detect the loop freq
  
  Do
call control()        'a control function
putpin(14,1)
  putpin(14,0)
  delay(2.5e-4)
  loop
  
I observed the pin and calucated the freq which it is very high that out of my
expectation.
      Actually I need to write two tasks to  control, using PID, the motor rotational
angle, one is current control task  with loop freq 4000Hz, and the other is angle control
task with loop freq  2000Hz. Do you have any suggestion to fix the loop freq about
2000Hz~4000Hz
    Thanks
  Owen
  
raunig2003 <raunig2003@raun...> »¡¡G          FYI - If you have a time delay of
1.95ms then max loop freq is aprox. 
  500 hz or less.
  
  You should also consider the time of the called functions in your 
  loop when calculating your total loop time, not just the delay 
  function.
  
  What frequency did you get when you tried it out?
  
  rr
  
  --- In basicx@basi..., letter2email@... wrote:
  >
  > Hi~
  > 
  > I am new in BX24, my problem is shown below
  > 
  > Do
  > call control()        'a control function
  > delay(2.5e-4)
  > loop
  > 
  > I want the loop's freq is 4000Hz, but the min. time of delay
  > should be 1.95ms, so is that loop work? or any other suggestion?
  > 
  > Tahnks a lot
  > Owen
  >
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>   Do
> call control()        'a control function
> putpin(14,1)
>   putpin(14,0)
>   delay(2.5e-4)
>   loop
>  
> I observed the pin and calculated the freq which [] is very high, [beyond] my
expectation. [My translation]

If you need to run your control loop at 4KHz, I suggest that the BX-24p
is not the machine for you.  The machine can achieve that loop rate with
only minimal processing in the loop.

I don't understand how you could have measured a high frequency on the
pin.  The fastest loop that toggles a pin might be:
 do
	call putpin(14, 1)
	call putpin(14, 0)
 loop

On a BX-24p, that code will generate a ~9.6KHz signal.  If you add a
Call Delay() of any period greater than zero, you will introduce a
minimum two-tick pause per loop, reducing your loop rate to ~256Hz - if
whatever time your control function uses is disregarded - or less, if it
is considered.  Sleep will be little more useful, introducing either
~zero or a minimum one-tick pause, still far too large.

Another delay mechanism is available in PulseOut using a dummy pin, and
it offers much better resolution:
 do
	call putpin(14, 1)
	call putpin(14, 0)
	call PulseOut(0, 0.0001, 0)
 loop
will loop at ~4.056KHz, for example.

Still, this is not a good way to pace a fast sample or control loop, I
think.  I believe you'll do better with an external interrupt - which
you can generate with Timer1 or Timer2, connecting pin 26 or pin 25,
respectively, to the interrupt pin 11.  Keep your processing efficient
and minimal, or you will will not be able to maintain a rate you'd like.
	Tom
	

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Thanks you for your suggestion~
[]
	

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