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'BX-24 with Infra-Red length measurement
'Description: This application uses if else loops to give a distance in front
'of a GP2D12 Infra-red device that does not fit a linear response, the if and
'if else loops give an average function for voltage to distance conversion.
'*GP2D12 needs a separate power supply
'Created: 14/04/05 Revision: 1.0
'Written by: TR Control Solutions (Simon & Tobias)
'
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Dim Voltage As integer 'set variable names
Dim VoltageA As single
Dim Distance As single
Const ADC As Byte = 14 'set constants and addresses
Const GreenLED As Byte = 26
Const RedLED As Byte = 25
Const LEDon As Byte = 0
Const LEDoff As Byte = 1
Public Sub Main() 'start of program
Voltage = 0 'initialise variables
VoltageA = 0.0
Distance = 0.0
Do 'do loop allows continual running and update of distance
Voltage = getADC(ADC) 'read in voltage of sensor output
Call delay(0.5)
If voltage < 100 then ' if the distance or too far, saves processing time
Call PutPin(GreenLED, LEDoff)
Call Delay(0.04)
Call PutPin(RedLED, LEDon)
Else
Call PutPin(RedLED, LEDoff)
Call Delay(0.07)
Call PutPin(GreenLED, LEDon)
Call DistanceConverter () 'calculates the distance
If Distance < 70.0 then 'this is to do with unreliable response of sensor at short and long distances
If Distance > 11.5 then
Debug.Print Cstr(Distance) 'output for the distance to the debug screen on pc
End If
Else
Call PutPin(GreenLED, LEDoff)
Call Delay(0.04)
Call PutPin(RedLED, LEDon)
End If
End If
Loop 'end of do loop making program non-terminal
End Sub
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Sub DistanceConverter()
VoltageA = Csng(Voltage) 'converts integer to single for calculation purpose
VoltageA = VoltageA / 204.6 'converting adc result in bits to a real voltage
If VoltageA < 2.45 then
Distance = 10.0
If VoltageA > 1.4 then 'following statements return a piece wise result for distance
Distance = VoltageA - 3.5
Distance = Distance / (-0.105)
ElseIf VoltageA > 1.0 then
Distance = VoltageA - 2.2
Distance = Distance / (-0.04)
ElseIf VoltageA > 0.6 then
Distance = VoltageA - 1.6
Distance = Distance / (-0.02)
ElseIf voltageA > 0.45 then
Distance = VoltageA - 0.85
Distance = Distance / (-0.005)
End If
Else
Call PutPin(GreenLED, LEDoff)
Call Delay(0.04)
Call PutPin(RedLED, LEDon)
End If
End Sub 'returns to main.
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