I have a circuit working that basically flashes LED's in different sequences and then turns all LED's off upon button presses. It works good but what I'd like to do is add a sequence that instead of the LED's simply turning off, they fade out so as to look sort of like a "comet tail".

I'm using a PIC 12F675 and the code is below. If I could just be pointed in the right direction to know where to start I may be able to figure it out.

Thanks for any "pointing"

Code:
ANSEL=0
CMCON=7


Input GPIO.5
Low GPIO.0
Low GPIO.1
Low GPIO.2
Low GPIO.4

 

loop:
 
IF GPIO.5 = 0 Then
Pause 500 
GoSub pressI:
EndIF

GoTo loop

 

 


pressI:

High GPIO.0
Pause 50 
Low GPIO.0
Pause 50
High GPIO.0
Pause 50 
Low GPIO.0
Pause 50
High GPIO.1
Pause 50 
Low GPIO.1
Pause 50
High GPIO.1
Pause 50 
Low GPIO.1
Pause 50
High GPIO.2
Pause 50 
Low GPIO.2
Pause 50
High GPIO.2
Pause 50 
Low GPIO.2
Pause 50

IF GPIO.5 = 0 Then
Pause 500 
GoSub pressII:
EndIF

GoTo pressI


pressII:

High GPIO.0
Pause 75 
Low GPIO.0
Pause 75
High GPIO.1
Pause 75 
Low GPIO.1
Pause 75
High GPIO.2
Pause 75 
Low GPIO.2
Pause 95
High GPIO.2
Pause 75 
Low GPIO.2
Pause 75
High GPIO.1
Pause 75 
Low GPIO.1
Pause 75
High GPIO.0
Pause 75 
Low GPIO.0
Pause 95

IF GPIO.5 = 0 Then 
Pause 500
GoSub pressIII:
EndIF

GoTo pressII


pressIII:

High GPIO.2
Pause 75 
Low GPIO.2
Pause 75
High GPIO.1
Pause 75 
Low GPIO.1
Pause 75
High GPIO.0
Pause 75 
Low GPIO.0
Pause 95

 

IF GPIO.5 = 0 Then 
Pause 500
GoSub pressIIII:
EndIF

GoTo pressIII

 

pressIIII:

High GPIO.4
Pause 5 
Low GPIO.4
Pause 5

IF GPIO.5 = 0 Then 
Pause 500
GoSub strobe:
EndIF

GoTo pressIIII


strobe:

High GPIO.4
Pause 25 
Low GPIO.4
Pause 25
High GPIO.4
Pause 25 
Low GPIO.4
Pause 25
High GPIO.4
Pause 25 
Low GPIO.4
Pause 25
High GPIO.4
Pause 25 
Low GPIO.4
Pause 1000


IF GPIO.5 = 0 Then 
Pause 500
GoSub loop:
EndIF

GoTo strobe