global [a b c d bits y]


to init
   write portb-ddr 0
   write portb 0
   setbit 4 portb
   setbits 0
   sety 0
end

to clock
   setbit 6 portb
   repeat 20 [no-op]
   clearbit 6 portb
end

to latch
   setbit 5 portb
   repeat 20 [no-op]
   clearbit 5 portb
end

to on
   setbit 7 portb
   ;repeat 100 [no-op]
end

to off
   ;repeat 100 [no-op]
   clearbit 7 portb
end

to justone :n
   setn :n - 1
   blank
   on clock repeat n [off clock]
   latch
   clearbit 4 portb
   flicker
end

to any-thirty
   setbits random % 2	;randomly select 1 or 0 only
   
   ;depending on the randomly selected bits, the LogoChip
   ;will send 1's or 0's until there are 30 1's.
   ;it will then display/light the LEDs

   if (bits = 1) [on clock sety y + 1]

   if (bits = 0) [off clock]
   if (y > 30) [
	sety 0
	latch
	flicker
	blank
	]
   any-thirty
end


;Flicker and fade out effect
;B4 controls the output enable of the LED drivers
to flicker
   repeat 5 [
	clearbit 4 portb
	mwait 1
	setbit 4 portb
	mwait 10
	]
   repeat 10 [
	clearbit 4 portb
	mwait 10
	setbit 4 portb
	mwait 20
	]
   repeat 6 [
	clearbit 4 portb
	mwait 5
	setbit 4 portb
	mwait 30
	]
   repeat 5 [
	clearbit 4 portb
	mwait 1
	setbit 4 portb
	mwait 10
	]

end



to blank
   repeat 48 [off clock]
   latch
end

;Lights up all LEDs - useful for checking which ones are out
to all
   on
   repeat 50 [clock mwait 10]
   latch 
   clearbit 4 portb
end 

to powerup
   init
   all
end

to startup
   init
   loop [any-thirty]
end