Jan Axelson, USB Complete
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Chapter 14
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The application can request and store information about each of the interface’s
endpoints in turn.
For i As Int32 = 0 To ifaceDescriptor.bNumEndpoints - 1
WinUsb_QueryPipe _
(myDevInfo.winUsbHandle, _
0, _
Convert.ToByte(i), _
pipeInfo)
If ((pipeInfo.PipeType = _
USBD_PIPE_TYPE.UsbdPipeTypeBulk) And _
UsbEndpointDirectionIn(pipeInfo.PipeId)) Then
myDevInfo.bulkInPipe = pipeInfo.PipeId
ElseIf ((pipeInfo.PipeType = _
USBD_PIPE_TYPE.UsbdPipeTypeBulk) And _
UsbEndpointDirectionOut(pipeInfo.PipeId)) Then
myDevInfo.bulkOutPipe = pipeInfo.PipeId
ElseIf (pipeInfo.PipeType = _
USBD_PIPE_TYPE.UsbdPipeTypeInterrupt) And _
UsbEndpointDirectionIn(pipeInfo.PipeId) Then
myDevInfo.interruptInPipe = pipeInfo.PipeId
ElseIf (pipeInfo.PipeType = _
USBD_PIPE_TYPE.UsbdPipeTypeInterrupt) And _
UsbEndpointDirectionOut(pipeInfo.PipeId) Then
myDevInfo.interruptOutPipe = pipeInfo.PipeId
End If
Next i
8%
Definitions
internal enum USBD_PIPE_TYPE
{
UsbdPipeTypeControl,
UsbdPipeTypeIsochronous,
UsbdPipeTypeBulk,
UsbdPipeTypeInterrupt,
}
Using WinUSB for Vendor-Defined Functions
357
[StructLayout(LayoutKind.Sequential)]
internal struct WINUSB_PIPE_INFORMATION
{
internal USBD_PIPE_TYPE PipeType;
internal Byte PipeId;
internal ushort MaximumPacketSize;
internal Byte Interval;
}
[DllImport("winusb.dll", SetLastError = true)]
internal static extern Boolean WinUsb_QueryPipe
(IntPtr InterfaceHandle,
Byte AlternateInterfaceNumber,
Byte PipeIndex,
ref WINUSB_PIPE_INFORMATION PipeInformation);
Use
The UsbEndpointDirectionIn and UsbEndpointDirectionOut functions
enable querying the direction of an endpoint:
private Boolean UsbEndpointDirectionIn(Int32 addr)
{
Boolean directionIn;
if (((addr & 0X80) == 0X80))
{ directionIn = true; }
else
{ directionIn = false; }
}
return directionIn;
}
private Boolean UsbEndpointDirectionOut(Int32 addr)
{
Boolean directionOut;
if (((addr & 0X80) == 0))
{ directionOut = true; }
else
{ directionOut = false; }
return directionOut;
}
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The application can request and store information about each of the interface’s
endpoints in turn.
for ( Int32 i=0; i <= ifaceDescriptor.bNumEndpoints - 1; i++ )
{
WinUsb_QueryPipe
(myDevInfo.winUsbHandle,
0,
Convert.ToByte(i),
ref pipeInfo);
if (((pipeInfo.PipeType ==
USBD_PIPE_TYPE.UsbdPipeTypeBulk) &&
UsbEndpointDirectionIn(pipeInfo.PipeId)))
{
myDevInfo.bulkInPipe = pipeInfo.PipeId;
}
else if (((pipeInfo.PipeType ==
USBD_PIPE_TYPE.UsbdPipeTypeBulk) &&
UsbEndpointDirectionOut(pipeInfo.PipeId)))
{
myDevInfo.bulkOutPipe = pipeInfo.PipeId;
}
else if ((pipeInfo.PipeType ==
USBD_PIPE_TYPE.UsbdPipeTypeInterrupt) &&
UsbEndpointDirectionIn(pipeInfo.PipeId))
{
myDevInfo.interruptInPipe = pipeInfo.PipeId;
}
else if ((pipeInfo.PipeType ==
USBD_PIPE_TYPE.UsbdPipeTypeInterrupt) &&
UsbEndpointDirectionOut(pipeInfo.PipeId))
{
myDevInfo.interruptOutPipe = pipeInfo.PipeId;
}
}
&GVCKNU
The PipeId value equals bEndpointAddress in the endpoint descriptor. A valid
endpoint has a PipeId greater than zero. The USBD_PIPE_TYPE enumerator
includes an entry for isochronous pipes, but the WinUSB driver doesn’t sup-
port isochronous transfers.
Using WinUSB for Vendor-Defined Functions
359
5GVVKPI2KRG2QNKEKGU
After identifying an endpoint, an application can set vendor-specific policies for
transfers at the endpoint. Table 14-1 shows the policies.
8$ Definitions
Friend Enum POLICY_TYPE As UInt32
SHORT_PACKET_TERMINATE = 1
AUTO_CLEAR_STALL
PIPE_TRANSFER_TIMEOUT
IGNORE_SHORT_PACKETS
ALLOW_PARTIAL_READS
AUTO_FLUSH
RAW_IO
End Enum
' Use this definition when the returned Value parameter is a Byte
' (all except PIPE_TRANSFER_TIMEOUT):
<DllImport("winusb.dll", SetLastError:=True)> _
Friend Shared Function WinUsb_SetPipePolicy _
(ByVal InterfaceHandle As IntPtr, _
ByVal PipeID As Byte, _
ByVal PolicyType As UInt32, _
ByVal ValueLength As UInt32, _
ByRef Value As Byte) _
As Boolean
End Function
' Use this alias when the returned Value parameter
' is a UInt32 (PIPE_TRANSFER_TIMEOUT only):
<DllImport("winusb.dll", EntryPoint:="WinUsb_SetPipePolicy", SetLastError:=True)> _
Friend Shared Function WinUsb_SetPipePolicy1 _
(ByVal InterfaceHandle As IntPtr, _
ByVal PipeID As Byte, _
ByVal PolicyType As UInt32, _
ByVal ValueLength As UInt32, _
ByRef Value As UInt32) _
As Boolean
End Function
Chapter 14
360
Table 14-1: The WinUsb_SetPipePolicy function can specify how the driver
responds to various conditions when performing a transfer and whether data
bypasses WinUSB’s queuing and error handling.
2CTCOGVGT 8CNWG &GHCWNV &GUETKRVKQP
SHORT_PACKET_TERMINATE 01h False If True, terminate a write transfer
that is a multiple of wMaxPacketSize
with a ZLP.
AUTO_CLEAR_STALL 02h False If True, clear a stall condition
automatically.
PIPE_TRANSFER_TIMEOUT 03h Zero Set a transfer timeout interval in
milliseconds. Zero = never time out.
IGNORE_SHORT_PACKETS 04h False If True, complete a read operation
only on receiving the specified
number of bytes. If False, complete a
read operation on receiving the
specified number of bytes or a short
packet.
ALLOW_PARTIAL_READS 05h True Sets the policy if the endpoint
returns more data than requested. If
True, complete the read operation
and save or discard the extra data as
specified by AUTO_FLUSH. If
False, fail the read request.
AUTO_FLUSH 06h False If True and
ALLOW_PARTIAL_READS is also
True, discard extra data. If False and
ALLOW_PARTIAL_READS is
True, save extra data and return it in
the next read operation. If
ALLOW_PARTIAL_READS is
False, ignore.
RAW_IO 07h False Determines whether calls to
WinUsb_ReadPipe bypasses
WinUSB's queuing and error
handling, If True, calls pass directly
to the USB stack, and the read buffer
must be a multiple of
wMaxPacketSize and less than the
host controller’s maximum per
transfer. If False, calls don’t pass
directly to the USB stack, and the
buffers don’t have the size
restrictions.
Using WinUSB for Vendor-Defined Functions
361
Use
With these overloaded functions, you can call SetPipePolicy to set a policy with
a Byte or UINT32 value as needed.
Private Function SetPipePolicy _
(ByVal pipeId As Byte, ByVal policyType As UInt32, ByVal value As Byte) _
As Boolean
Dim success As Boolean = WinUsb_SetPipePolicy _
(myDevInfo.winUsbHandle, _
pipeId, _
policyType, _
1, _
value)
Return success
End Function
Private Function SetPipePolicy _
(ByVal pipeId As Byte, ByVal policyType As UInt32, ByVal value As UInt32) _
As Boolean
Dim success As Boolean = WinUsb_SetPipePolicy1 _
(myDevInfo.winUsbHandle, _
pipeId, _
policyType, _
4, _
value)
Return success
End Function
Call the functions to set policies for an endpoint:
Dim success As Boolean
SetPipePolicy _
(myDevInfo.bulkInPipe, _
POLICY_TYPE.IGNORE_SHORT_PACKETS, _
Convert.ToByte(False))
Dim pipeTimeout As UInt32 = 2000
Chapter 14
362
success = SetPipePolicy _
(myDevInfo.bulkInPipe, _
POLICY_TYPE.PIPE_TRANSFER_TIMEOUT, _
pipeTimeout)
8%
Definitions
internal enum POLICY_TYPE
{
SHORT_PACKET_TERMINATE = 1,
AUTO_CLEAR_STALL,
PIPE_TRANSFER_TIMEOUT,
IGNORE_SHORT_PACKETS,
ALLOW_PARTIAL_READS,
AUTO_FLUSH,
RAW_IO,
}
// Use this definition when the returned Value parameter is a Byte
// (all except PIPE_TRANSFER_TIMEOUT):
[DllImport("winusb.dll", SetLastError = true)]
internal static extern Boolean WinUsb_SetPipePolicy
(IntPtr InterfaceHandle,
Byte PipeID,
UInt32 PolicyType,
UInt32 ValueLength,
ref Byte Value);
// Use this alias when the returned Value parameter is a UInt32
// (PIPE_TRANSFER_TIMEOUT only):
[DllImport("winusb.dll", SetLastError = true, EntryPoint = "WinUsb_SetPipePolicy")]
internal static extern Boolean WinUsb_SetPipePolicy1
(IntPtr InterfaceHandle,
Byte PipeID,
UInt32 PolicyType,
UInt32 ValueLength,
ref UInt32 Value);
Using WinUSB for Vendor-Defined Functions
363
Use
With these overloaded functions, you can call SetPipePolicy to set a policy with
a Byte or UINT32 value as needed.
private Boolean SetPipePolicy( Byte pipeId, UInt32 policyType, Byte value )
{
Boolean success = WinUsb_SetPipePolicy
( myDevInfo.winUsbHandle,
pipeId,
policyType,
1,
ref value ;
return success;
}
private Boolean SetPipePolicy( Byte pipeId, UInt32 policyType, UInt32 value )
{
Boolean success = WinUsb_SetPipePolicy1
( myDevInfo.winUsbHandle,
pipeId,
policyType,
4,
ref value );
return success;
}
Call the functions to set policies for an endpoint:
Boolean success;
success = SetPipePolicy
( myDevInfo.bulkInPipe,
Convert.ToUInt32(POLICY_TYPE.IGNORE_SHORT_PACKETS),
Convert.ToByte(false));
UInt32 pipeTimeout = 2000;
success = SetPipePolicy
(myDevInfo.bulkInPipe,
Convert.ToUInt32(POLICY_TYPE.PIPE_TRANSFER_TIMEOUT),
pipeTimeout);
Chapter 14
364
&GVCKNU
The WinUsb_SetPipePolicy function accepts a Byte for the value parameter for
all policies except PIPE_TRANSFER_TIMEOUT, which requires a UINT32.
To handle both types, the code provides a definition that accepts a Byte value
and an alias that accepts a UINT32. Two overloaded SetPipePolicy functions
accept different value parameter types and pass the parameter to
WinUsb_SetPipePolicy.
The Byte parameters have true/false meanings, so for readability, the Set-
PipePolicy function accepts a Boolean value, and the Convert.ToByte method
converts to a Byte for passing to WinUsb_SetPipePolicy.
The example sets two policies for the bulk IN endpoint. In a similar way, you
can set policies for all of the interface’s endpoints. A companion function for
reading pipe policies is WinUsb_GetPipePolicy.
9TKVKPI&CVCXKC$WNMCPF+PVGTTWRV6TCPUHGTU
The WinUsb_WritePipe function can write data using bulk or interrupt trans-
fers.
8$ Definitions
<DllImport("winusb.dll", SetLastError:=True)> _
Friend Shared Function WinUsb_WritePipe _
(ByVal InterfaceHandle As IntPtr, _
ByVal PipeID As Byte, _
ByVal Buffer() As Byte, _
ByVal BufferLength As UInt32, _
ByRef LengthTransferred As UInt32, _
ByVal Overlapped As IntPtr) _
As Boolean
End Function
Use
Dim buffer(1) As Byte
Dim bytesToWrite As UInt32 = 2
Dim bytesWritten As UInt32
Dim success As Boolean
Using WinUSB for Vendor-Defined Functions
365
' Place data in the buffer to send. Example:
buffer(0) = 72
buffer(1) = 105
bytesToWrite = Convert.ToUInt32(buffer.Length)
success = WinUsb_WritePipe _
(myDevInfo.winUsbHandle, _
myDevInfo.bulkOutPipe, _
buffer, _
bytesToWrite, _
bytesWritten, _
IntPtr.Zero)
8%
Definitions
[DllImport("winusb.dll", SetLastError = true)]
internal static extern Boolean WinUsb_WritePipe
(IntPtr InterfaceHandle,
Byte PipeID,
Byte[] Buffer,
UInt32 BufferLength,
ref UInt32 LengthTransferred,
IntPtr Overlapped);
Use
Byte[] buffer = new Byte[2];
UInt32 bytesToWrite = 2;
UInt32 bytesWritten = 0;
Boolean success;
// Place data in the buffer to send. Example:
buffer[0] = 72;
buffer[1] = 105;
bytesToWrite = Convert.ToUInt32( buffer.Length);
success = WinUsb_WritePipe
(myDevInfo.winUsbHandle,
myDevInfo.bulkOutPipe,
buffer,
bytesToWrite,
ref bytesWritten,
IntPtr.Zero);