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Sample Parallel Port I/O Program Listing |
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Sample Parallel Port I/O Program Listing |
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'Parallel port I/O program
'David A. Ward March 2000
'The flashing LED show uses 8 LED's with their anodes connected
'to D0 through D7 (pins 2 through 9) of the parallel printer port with
'430 ohm series resistors.
'The read from port routine reads 8 bits connected through
'a DIP switch using 8-4.7K pull-down resistors. Switches
'open reads in as a
'inpout32.dll must be in the Windows\Systems directory
'for the INP and OUT commands to work.
'the following code must also be in a separate module:
'Public Declare Function Inp Lib "inpout32.dll" _
'Alias "Inp32" (ByVal PortAddress As Integer) As Integer
'Public Declare Sub Out Lib "inpout32.dll" _
'Alias "Out32" (ByVal PortAddress As Integer, ByVal Value
Option Explicit
Dim X, Y, T, Z, PortAddress, LowNib, HighNib, Number, Total As Integer
'Flashing LED show
Private Sub cmdShow_Click()
MousePointer = 13 'change cursor to indicate the program
is busy
'shift LED's from LSB up through MSB
Z = 0
While Z < 10
X = 0
While X < 8
Out PortAddress, 2 ^ X
Call Delay
X = X + 1
Wend
'Shift LED's from MSB down through LSB
X = 7
While X > -1
Out PortAddress, 2 ^ X
Call Delay
X = X - 1
Wend
Z = Z + 1
Wend
Z = 0
While Z < 10
Out PortAddress, 0
Out PortAddress, 170
Call Delay
Out PortAddress, 85
Call Delay
Z = Z + 1
Wend
Out PortAddress, 0
MousePointer = 0
End Sub
'Delay subroutine
Private Sub Delay()
Dim PauseTime, Start
PauseTime = 0.01 ' Set duration.
Start = Timer ' Set start time.
Do While Timer < Start + PauseTime
DoEvents
' Yield to other processes.
Loop
End Sub
'Write check box data to the parallel port
Private Sub cmdWriteToPort_Click()
If Check1(0).Value = vbChecked Then Number = 1:
Shape1(0).FillColor = &HFF& Else Shape1(0).FillColor = &H0&
If Check1(1).Value = vbChecked Then Number = Number
+ 2: Shape1(1).FillColor = &HFF& Else Shape1(1).FillColor = &H0&
If Check1(2).Value = vbChecked Then Number = Number
+ 4: Shape1(2).FillColor = &HFF& Else Shape1(2).FillColor = &H0&
If Check1(3).Value = vbChecked Then Number = Number
+ 8: Shape1(3).FillColor = &HFF& Else Shape1(3).FillColor = &H0&
If Check1(4).Value = vbChecked Then Number = Number
+ 16: Shape1(4).FillColor = &HFF& Else Shape1(4).FillColor = &H0&
If Check1(5).Value = vbChecked Then Number = Number
+ 32: Shape1(5).FillColor = &HFF& Else Shape1(5).FillColor = &H0&
If Check1(6).Value = vbChecked Then Number = Number
+ 64: Shape1(6).FillColor = &HFF& Else Shape1(6).FillColor = &H0&
If Check1(7).Value = vbChecked Then Number = Number
+ 128: Shape1(7).FillColor = &HFF& Else Shape1(7).FillColor = &H0&
Out PortAddress, Number
Text1.Text = Number
Number = 0
End Sub
'Read binary data from the parallel port
Private Sub CmdRead_Click()
Out PortAddress + 2, 15
Out PortAddress + 1, 128
LowNib = (Inp(PortAddress + 2) And 15)
HighNib = (Inp(PortAddress + 1) And 240)
Total = LowNib + HighNib
Text2.Text = Total
If Total And 1 Then Text3(0).Text = "1" Else Text3(0)
= "0"
If Total And 2 Then Text3(1).Text = "1" Else Text3(1)
= "0"
If Total And 4 Then Text3(2).Text = "1" Else Text3(2)
= "0"
If Total And 8 Then Text3(3).Text = "1" Else Text3(3)
= "0"
If Total And 16 Then Text3(4).Text = "1" Else Text3(4)
= "0"
If Total And 32 Then Text3(5).Text = "1" Else Text3(5)
= "0"
If Total And 64 Then Text3(6).Text = "1" Else Text3(6)
= "0"
If Total And 128 Then Text3(7).Text = "1" Else Text3(7)
= "0"
Out PortAddress, Total
End Sub
'Change port address
Private Sub Port_Click()
PortAddress = Port.Text
End Sub
'Clear out bits on form and set all port bits to 0
Private Sub CmdClear_Click()
For X = 0 To 7
Check1(X).Value = False
Shape1(X).FillColor = &H0&
Text3(X) = ""
Next X
Number = 0
Out PortAddress, Number
Text1.Text = Number
Text2.Text = Number
End Sub
Private Sub Form_Load()
'Test program for inpout32.dll
'Change PortAddress to match the port address to write to:
'Usual parallel-port addresses are:
'&h378 (888), &h278 (632), &h3BC (956)
PortAddress = 888
Out PortAddress + 2, 15
Port.Text = PortAddress
End Sub