Code for a one Button RUN / STOP for the BS1

Clovey

Hello,
I can't seem to figure this one out...
The push button switch is one active low normally open contact which closes when pushed. (P0=0)
My goal is to press the button once to RUN and the same button again to STOP. A flag bit (Bit 0) would change state with Run and STOP. Thanks, Jim

j.aaa8jr@gmail.com

VonSzarvas

Hi @Clovey

I don't have the hardware setup to try, but would something like this work for you ?

' BUTTON.BS2
' Connect an active-low circuit to pin P0 of the BS2. When you press the
' button, the DEBUG screen will display an asterisk (*). The program, as
' shown below, will print an asterisk at the first button press, then
' delay approximately one second (200 x 5 ms PAUSE) before auto-repeating
' at a rate of approximately 100 ms (5 x 20 ms).  Feel free to modify the
' program to see the effects of your changes on the way BUTTON responds.

' {$STAMP BS2}
' {$PBASIC 2.5}

Btn             PIN     0

btnWrk          VAR     Byte
btnLastState    VAR     Byte

btnLastState = 0

Main:
  ' Try changing the Delay value (255) in BUTTON to see the effect of
  ' its modes: 0 = no delay; 1-254 = varying delays before auto-repeat;
  ' 255 = no auto-repeat (only one action per button press)
  '
  ' The BUTTON instruction will cause the program to branch to
  ' No_Press unless P0 = 0

  PAUSE 5
  BUTTON Btn, 0, 200, 20, btnWrk, 0, No_Press

  IF btnLastState = 1 THEN
    btnLastState = 0
    DEBUG "RUN"
  ELSE
    btnLastState = 1
    DEBUG "STOP"
  ENDIF

No_Press:
  GOTO Main

JonnyMac

I used to write a hundred or so BS1 programs every year around Halloween for people using the EFX-TEK Prop-1 controller (has nothing to do with the Propeller 1 which was released after the BS1-powered Prop-1). To do what you want reliably, you'll want a debounce and force the button to be released. You could do it in a subroutine like this:

Check_Button:
  timer = 0

CB_Now:
  IF Trigger = NotPressed THEN CB_Exit 
    PAUSE 5
    timer = timer + 5
    IF timer < 50 THEN CB_Now

CB_Release:
      IF Trigger = Pressed THEN CB_Release      ' force release
      PAUSE 100                                 ' let button clear
      state = state ^ 1                         ' flip state

CB_Exit:
  RETURN

This ensures a good button press and then allows a clean release. In the main body of your code you could do something like this.

Main:
  GOSUB Check_Button
  BRANCH state, (State_0, State_1)


State_0:
  ' code for state 0
  GOTO Main


State_1:
  ' code for state 1
  GOTO Main

The attached listing compiles, but I did not connect to a BS1.