CPU = 12F675
MHZ = 4
CONFIG 12692

' *******************************************
' PIC program for boiler LED opto-sensor
' 
' 8-pin PIC 12F675, internal 4-MHz clock, internal A/D converter
' 10 bit a/d = 1024 units
' full-scale = 5v = 1024, 0 = 0v 
'
' if switch = 0 volts then trigger event locks to 6.5 minutes
'
' Bytes Free: 32
' *******************************************

input   GP0			' switch on pin 7
input 	GP1                	' a/d input = an1 on pin 6     
swi     var gpio.bit0		' define variable for state of pin 7
delay   var byte		'
adcono  equ $1f  		' adcono address location
option_reg.bit7  = 0  		' enable weak pull-ups (wpu)
wpu     = %00000001  		' uses internal 10k resistor for switch
ansel   = %01010010   		' xxxx0010 = ans1 = a/d input on pin 6

'-------------------------------

main:

adcono = %10000101            	' turn a/d on + use pin 6
pause 300 			' 300 mSecs delay
adcono = %10000111            	' start conversion  
loop:				'
if adcon0.bit1 = 1 then loop  	' loop until go/done bit 1 = 0
adcono = 0                    	' turn off a/d
				' a/d result is stored in 2 bytes
				' called adresH and adresL

serout 	GP5,n1200-5,[dec ((adresh * 256) + adresl),10,13]   

                                ' -5 for osc. calibration.
				' PIC outputs a/d result as decimal
				' on pin 2 (= GP5) at ~1200 baud.
if swi = 1 then main		' get next a/d sample if switch is OFF

'-------------------------------

' get next a/d sample if switch is ON and a/d result is still rather small
' and within a noise margin

if ((adresh * 256) + adresl) < 50 then main

'--------------------------------

' program gets to here if switch is ON and a/d signal > 0.245 volt is sensed.
' i.e. 50 = noise level i.e. 50 x 0.0049v = 0.245 v

' this next bit adds 6.5 minutes delay

delay = 6
loop1:
pause 65000			' pause 65 secs, x 6  = 6.5 mins
delay = delay - 1
if delay > 0 then loop1 
                              
goto   main

end

' --------------------------------
' this delay isn't very good but does work. It's limited by the lack of
' code space using Basic and a small PIC chip. The PIC outputs a data number
' greater than 50 and then stays locked in this delay loop. 
' fleXYlog continously processes this data number until a new number is sent 
' by the PIC chip 6 minutes later.