' AV-Fan.bas
' control A/V cabinet cooling fan based on temperature reported by DS18B20
'
' Adapted from DS18B20_08M_3.Bas - PICAXE-08M
'
' Illustrates an interface with the DS18B20 in monitoring temperature.  An alarm
' is associated with the temperature.
'
' If the temperature measured on the DS18B20 associated with IN1 is abve HighTrip, a relay
' on Out4 (term 3) is operated.  It is released when the temperature falls below LowTrip
'
' Note that HighTrip and LowTrip are specified as the temperature plus 60 degrees C to avoid
' working with negative numbers.
'
' Note that a 4.7K pullup to +5 VDC is required on the DQ lead.  +5 VDC is required on the
' V+ terminal of the DS18B20.
'
'  08M					DS18B20
'
' IO1 (term 7) ------------------ DQ (term 2)
'
'                            2N4401 ---(M)-- +
'                                 |/
' OUT4 (term 3) ------- 4K7 ----->|\
'                                   -- GRD
'
' Uses 65 of 256 bytes.
'
' original DS18B20 code copyright, Peter H Anderson, Baltimore, MD, Sept, '04
' AV-Fan changes copyright John E Carter 24 Sept 2006

	symbol counter = b1
    Symbol TempC_100 = W3
    Symbol DevNum = W6
    Symbol Temp_8 = B9

    Symbol HighTrip = 90	'(86F)	' 30 + 60 - adjust as necessary
    Symbol LowTrip = 88       '(82.4F)	' 28 + 60

	low 0		'set unused pin

	high 4	'operation verification on power up (fan on)
	high 2	'(status LED on)
	pause 600
	low 2
    Low 4	' turn off alarm
Top:
	high 2			'indicate a read is in progress (power/activity light)
      ReadTemp 1, Temp_8		' read the high 8 bits - approx temp in deg C
	low 2



    ' respond to the temperature
    Temp_8 = Temp_8 + 60	' to avoid negative numbers
    If Temp_8 >= HighTrip Then OperateAlarm
	if Temp_8 < LowTrip then continue
	'indicate if above LowTrip but below HighTrip
	for counter = 1 to 2
		pause 200
		high 2
		pause 200
		low 2
	next counter

continue:
    If Temp_8 < LowTrip Then ReleaseAlarm
    ' else
    Goto SequenceDone

OperateAlarm:
    High 4
    Goto SequenceDone

ReleaseAlarm:
    Low 4
    Goto SequenceDone

SequenceDone:
    Pause 1000	'was 20000
    GoTo Top