Seemed easy in theory

Eric R

Yesterday I started what I thought would be a simple piece of BS2 code... well, that was yesterday.

IN8·was going to be my "program enable" input,
IN11·was going to be my "toggle /·step select" input
12 was going to be pulsout.

The theory was·IF IN8=1· then everytime IN11 was toggled it would advance·a "variable" stepping 1 to 8·as follows:

IF variable = 1 THEN PULSOUT 12,960
IF variable = 2 THEN PULSOUT 12, 1200
and so on...

Once IN8=0 output 12 would toggle to a input for use·as a counter later in the program and the stored variable would then become a comparator·for the counter. This counter and comparator work fine however stepping 1 to 8 and pulsing out at each step along with storing the variable upon IN8=0 has become a burden. How would you guys handle this?

··

Tracy Allen

I'm not sure I understand exactly what you want to do, but this kind of problem often can be programmed as a state machine:

   nowstate VAR bit
   oldstate VAR bit
   change VAR bit
   bark  VAR word
   oldstate = in11
  DO
     nowstate = in11
     change = nowstate ^ oldstate
     oldstate = newstate   ' update state variable
    IF change THEN
      variable = variable+1
      LOOKUP variable,[noparse][[/noparse]960,1200,  etc],bark
      PULSOUT 12,bark
   ENDIF
  LOOP UNTIL in8=0
'  come here when in8=0

That would, if I have it right, count on both the rising and falling edge of in11. Note that the entire DO:LOOP executes over and over rapidly, but the IF clause only executes when there is a change in in11.

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Tracy Allen
www.emesystems.com

Eric R

You are very close! I did find a similar method with good results. I will spend a few more hours on this trying to figure out how to store the selected "variable"·and then terminate the pulsout command after the selection is made. Thanks for your help!