quick questions about dira , and outa

mikediv · 2010-03-25 18:06

Guys a quick question I know how to blink an LED with the prop but I was wondering if you look at this simple code

pub blink

dira [noparse][[/noparse] 0 ] : = 1
outa [noparse][[/noparse] 0 ] : = 1

outa [noparse][[/noparse] 0 ] : = 0

repeat

I understand how to use delay and make an LED blink but I was wondering why this code does not work I tried it using scope but the output just sits a 0 wouldn't the code start back at outa 1 then cycle down to outa 0 and then back and forth hence a blinking LED ???

pullmoll · 2010-03-25 18:09

mikediv said...
wouldn't the code start back at outa 1 then cycle down to outa 0 and then back and forth hence a blinking LED ???

Why should it? The Spin interpreter can't know where you want to loop. The repeat repeats instructions that are indented:

    dira[noparse][[/noparse]0] := 1
    repeat
      outa[noparse][[/noparse]0] := 1
      outa[noparse][[/noparse]0] := 0

This should toggle port 0 as fast as possible in Spin

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Next day he was buried. Face down, nine edge first.

Joms · 2010-03-25 18:48

You could also use:

 
dira[noparse][[/noparse]0] := 1                   'Set direction of Pin 0
 
Repeat                         'Repeat following indented instructions
  !outa[noparse][[/noparse]0]                     'toggle pin 0
  waitcnt(clkfreq + cnt)       'wait 1 second

instead of:

dira[noparse][[/noparse]0] := 0                 'Set direction of Pin 0
 
Repeat                       'Repeat following indented instructions
  outa[noparse][[/noparse]0] := 1               'set pin 0 high
  outa[noparse][[/noparse]0] := 0               'set pin 0 low
  waitcnt(clkfreq + cnt)     'wait 1 second

Using the '!' is the toggle function and will just change the output from the current state to the reverse. Also, if it blinks to fast you may have to add a wait command, which I would highly recommend as currently your timing may very. I did put a wait line in my example, but you can change the time or remove it if you wish.

Post Edited (Joms) : 3/25/2010 6:53:24 PM GMT

mikediv · 2010-03-26 00:34

No you don't understand Joms thank you for the code but I know how to do it ,, What I am asking and forget the indentation I understand that to ,, I was just showing my question

Why wont the code

pub whatever

dira [noparse][[/noparse] 0 ] : = 1 set P0 to output
outa [noparse][[/noparse] 0 ] : = 1 set P0 to logic high

outa [noparse][[/noparse] 0 ] : = 0 set the P0 back to low or 0

repeat repeat the code from the start

Why will this not set P0 to blink on and off

If you leave out the outa [noparse][[/noparse] 0 ] : = 0 line this code will just set P0 to an output of high and then just loop forever
So why does it not set P0 high and then low and just repeat the whole thing over and over this is what I am asking I know how to do it the way the prop manual and the educational kit show it I am asking why this specific code the way I have it written will not blink P0 on and off

OH pullmoll I did not see your whole comment I didn't read past the "why should it " part I see reading on that you are saying I did not indent the code properly

Thank you I just wanted to know why this code would not work and that is exactly the info I was looking for

Post Edited (mikediv) : 3/26/2010 12:41:20 AM GMT

jazzed · 2010-03-26 18:02

@mikediv,
Just mentioning incase you forgot ... you need some delay between the outa so your eyes can detect the on/off.
Joms' first example is a very nice way to do the blink if that's all you want to do. Expanding on your method though:

pub start
  repeat
    whatever

pub whatever 
  dira [noparse][[/noparse] 0 ] : = 1 'set P0 to output 
  outa [noparse][[/noparse] 0 ] : = 1 'set P0 to logic high 
  waitcnt(clkfreq+cnt)
  outa [noparse][[/noparse] 0 ] : = 0 'set the P0 back to low or 0 
  waitcnt(clkfreq+cnt)

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Short answers?
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May you create something useful, even if it's just a hack.

mikediv · 2010-03-27 00:04

Jazzed,, guys thank you very much ,,, even after all this time I am still having trouble with the indentation using spin it makes sense once I see it but I still get tripped up sometimes.

pullmoll showed me where I was going wrong with indent and I really wanted to understand why it would not the work the way I had it my intent was to just see how fast the prop could switch back and forth with no timing and at 100 meg

OF course I am using an oscilloscope to be honest even with a 5 minute delay my eyes are getting so bad I would probably miss it lol

as always thank you all very much

quick questions about dira , and outa

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