di3558l1.txt
;***********************************************************************************
;
; LISTING 1 
;
; "Rainbow LED indicates voltage with color," EDN, December 7, 2004, pg 106
;
;***********************************************************************************

' PicBasic Pro program to read A/D on 12F675 ADC
' and display voltage A/D output using multi-color LED
' using a cold-to-hot color pallette.  Center of range
' is dark.
'
' (c) 2003 by David Prutchi
'

i       VAR     BYTE    ' Define loop variable
blue    VAR     BYTE    ' Define blue pulse-width variable
green   VAR     BYTE    ' Define green pulse-width variable
red     VAR     BYTE    ' Define red pulse-width variable
' GPIO port 0 to GREEN LED
' GPIO port 1 TO RED LED
' GPIO port 2 to BLUE LED
color   VAR     BYTE    ' Define LED color variable
x       VAR     BYTE	' Allocate A/D variable

' Set A/D Parameters
DEFINE ADC_BITS 8		' Use 10-bit A/D as 8-bit A/D
ANSEL.3=1				' Set ANS3 as analog input pin
ANSEL.4 = 0				' Set A/D clock
ANSEL.5 = 1
ANSEL.6 = 0
ADCON0.0 = 1            ' Turn On A/D
ADCON0.2 = 1			' A/D channel 3
ADCON0.3 = 1
ADCON0.6 = 0			' VDD is voltage reference
ADCON0.7 = 0            ' Left Justify result

' Set GPIO port pins 0, 1 and 2 as outputs
TRISIO.0=0
TRISIO.1=0
TRISIO.2=0


GoTo    mainloop        ' Skip subroutines

' SUBROUTINES
' -----------

' Subroutine to read a/d converter
getad:

       ADCON0.1 = 1            ' Start conversion
       PauseUs 50              ' Wait for conversion
       x = ADRESH
       Return


' MAIN
' ----

mainloop:


        GoSub   getad           ' Get x value by performing A/D conversion


		'  RGB ENCODING FUNCTION
		'  Convert A/D reading into color table
		'  Each color has 14 possible intensity levels


		IF x<=42 Then             'aqua
 		  	red=x/3
  	 	  	blue=14
 		  	green=(42-x)/3
		EndIF
		IF x>42 AND x<=84 Then   'shades of violet
  		 	red=(84-x)/3
 		 	green=0
	     	blue=14
		EndIF
		IF x>84 AND x<=126 Then  'shades of green 
  		 	red=0
  		 	green=0
 		 	blue=(126-x)/3
 		EndIF
 		IF x>126 AND x<=130 Then  'dark
   			red=0
   			green=0
   			blue =0
  		EndIF
		IF x>130 AND x<=172 Then  'shades of red
   			red=(x-130)/3
   			green=0
   			blue=0
		EndIF
		IF x>172 AND x<=214 Then  'red / orange / yellow
   			red=14
   			green=(x-172)/3
   			blue=0
		EndIF
		IF x>214 Then             'yellow to white
   			red=14
   			green=14
   			blue=(x-214)/3
		EndIF


		' PULSE WIDTH MODULATOR
		' Each PWM frame has 14 steps.

		For i = 1 TO 14  ' Cycle through 14 steps of frame
		color=0
   			IF red>0 Then
      			color=color+2
      			red=red-1
   			EndIF
   			IF green>0 Then
      			color=color+1
      			green=green-1
   			EndIF
   			IF blue>0 Then
      			color=color+4
      			blue=blue-1
   			EndIF
   			GPIO=color
			PauseUs 100     ' Allow LEDs to shine for a few microseconds
		Next i 
	GPIO=0
	GoTo    mainloop        ' Do it forever

End