[C.CC USERS] 3 Blinkin lights - other solutions

[Steve Pretty]

I tried the three (and 4 and 5!) Blinkin lights myself.  It is 
fascinating to see the kind of complex issues that can arise in 
concurrent code coming up in just three lines of code.  Using "Blink" on 
three LEDs is causing 18 (at least) occam processes to compete for 
processing cycles ( each Blink starts a tick (which starts a delay) and 
a pin.toggle (which starts a toggle and a digital.output).

Of course, if you just want three LEDs to flash in syncronism, you might 
be best just to use a single timer and distribute the output to three 
output functions - e.g.:

#INCLUDE "plumbing.module"

PROC delta3 (CHAN SIGNAL x?, x1!, x2!, x3!)
   WHILE TRUE
     SEQ
       x  ? SIGNAL
       x1 ! SIGNAL
       x2 ! SIGNAL
       x3 ! SIGNAL
:

PROC main ()
   CHAN SIGNAL s, s1, s2, s3:
   PAR
     tick (100, s!)

     delta3 (s?, s1!, s2!, s3!)

     pin.toggle (11, LOW, s1?)
     pin.toggle (10, LOW, s2?)
     pin.toggle (9, LOW, s3?)
:

All the lights run in synch using this approach. Well - actually, I put 
a logic analyser on it - becasue of the concurrency, the LEDs come on 
one after another, with the third coming on typically 5ms after the first.

The engineering side of me says that the simplest way to get three LEDS 
to blick in sync is to wire them in parallel!

Steve