altering behavior when a button is depressed for longer than n seconds

DylanB · 2006-03-10 08:38

Hi,

I have a simple routine for incrementing/decrementing a variable based on button states:

Get_Buttons:
  Btns = %1111                                  ' enable all four inputs
  FOR BtnIdx = 1 TO 5
    Btns = Btns & ~BtnBus                       ' test inputs
    PAUSE 5                                     ' delay between tests
  NEXT

  'check for a mode switch  (switch 0)
  IF Btns.BIT0 = 1 THEN
    motor_select = motor_select + 1 // 3      ' update motor_select    constrain  to 0-2
  ENDIF

 'check for an increase in dt (switch 1)
  IF Btns.BIT1 = 1 THEN
   dt(motor_select) = dt(motor_select) + 1   'it would be nice to increment this by 10 sometimes...
  ENDIF

 'check for a decrease in dt (switch 2)
  IF Btns.BIT2 = 1 THEN
   dt(motor_select) = dt(motor_select) - 1     'it would be nice to decrement this by 10 sometimes...
  ENDIF

 'check for motor enable/disable  (switch 3)
  IF Btns.BIT3 = 1 THEN
    motorEnable(motor_select) = motorEnable(motor_select) + 1 //2      'constrain to 0-1
    'start the clock for this motor
    idx = motor_select
    GOSUB Set_Time
  ENDIF

RETURN

I would like to increment a value by 10 instead of 1 if a button state remains the same for a couple seconds... kind of like how many alarm clocks work.

Any tips on how i could do this ?

Thanks!

Dylan

Jon Williams · 2006-03-10 14:51

If you're reading the the button(s) at a specific rate you can ad a counter that controls the increment rate.· Let's say you're scanning the button every 100 ms and after 1 second you want to change the increment rate.· You can do something like this:

· rate1 = rate1 + 1 * btns.BIT1
· IF (rate1 > 10) THEN
··· dt(motor_select)·=·dt(motor_select)·+·10
· ELSE
··· dt(motor_select)·=·dt(motor_select)·+·1
· ENDIF

Note that the first line of code will either add one to rate, or clear it based on the return value.· You need to be a little careful with this as rate could roll-over from its max value to zero if the variable size is too small for the amount of time the button could be pressed.

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Jon Williams
Applications Engineer, Parallax

Chris Savage · 2006-03-10 15:47

You could also put a MAX 11 after the line to limit it from ever rolling over, and then you could use a NIB variable.

  rate1 = rate1 + 1 * btns.BIT1 MAX 11

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Jon Williams · 2006-03-10 21:08

Thanks, Chris, I don't often use the MAX operator and that's a perfect application.

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Jon Williams
Applications Engineer, Parallax

DylanB · 2006-03-15 05:29

Thanks Joe and Chris for the great pointers. I was able to cobble together a solution like this:

'check for an increase in dt (switch 1)
  IF Btns.BIT1 = 1 THEN
   dt(motor_select) = dt(motor_select) + i
   i = i + 1   MAX 11        'constrain to NIB size
   IF(dt(motor_select) < 2 ) THEN
      dt(motor_select) = 2
      i = 1
   ENDIF
  ELSEIF Btns.BIT1 = 0 THEN
   i = 1
  ENDIF

 'check for a decrease in dt (switch 2)
  IF Btns.BIT2 = 1 THEN
   dt(motor_select) = dt(motor_select) - d
   d = d + 1 MAX 11          'constrain to NIB size
   IF(dt(motor_select) < 2 ) THEN
     dt(motor_select) = 2
     d = 1
   ENDIF
  ELSEIF  Btns.BIT2 = 0 THEN
   d = 1
  ENDIF

note the hack used to prevent the dt variable from going below 2 ... would a MIN 2 fix this ... :

'wonder if this would prevent dt(motor_select) from going below 2
dt(motor_select) = dt(motor_select) - d MIN 2

Any ideas?

Thanks again,

Dylan

Jon Williams · 2006-03-15 13:19

Using MIN in your hack will prevent dt(motor_select) from falling below 2, yes.

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Jon Williams
Applications Engineer, Parallax

Tracy Allen · 2006-03-15 17:04

You can replace this:

IF Btns.BIT1 = 1 THEN
   dt(motor_select) = dt(motor_select) + i
   i = i + 1   MAX 11        'constrain to NIB size
   IF(dt(motor_select) < 2 ) THEN
      dt(motor_select) = 2
      i = 1
   ENDIF
  ELSEIF Btns.BIT1 = 0 THEN
   i = 1
  ENDIF

with this

dt(motor_select) = dt(motor_select) + i MIN 2 MAX 300
i = (i + btns.bit1) * btns.bit1 MAX 11 MIN 1

Similarly for the second code block. That does not include setting i=1 when motor_select<2, I don't quite see what purpose that serves.

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Tracy Allen
www.emesystems.com

altering behavior when a button is depressed for longer than n seconds

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