Add new USB_Host_SetInterfaceAltSetting() convenience function.

Demos/Host/LowLevel/PrinterHost/PrinterHost.c

@@ -177,16 +177,7 @@ void USB_Printer_Host(void)
 			 * request to switch to the interface alternate setting with the Bidirectional protocol */
 			if (PrinterAltSetting)
 			{
-				USB_ControlRequest = (USB_Request_Header_t)
+				if ((ErrorCode = USB_Host_SetInterfaceAltSetting(PrinterInterfaceNumber, PrinterAltSetting)) != HOST_SENDCONTROL_Successful)
-					{
-						.bmRequestType = (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE),
-						.bRequest      = REQ_SetInterface,
-						.wValue        = PrinterAltSetting,
-						.wIndex        = PrinterInterfaceNumber,
-						.wLength       = 0,
-					};
-
-				if ((ErrorCode = USB_Host_SendControlRequest(NULL)) != HOST_SENDCONTROL_Successful)
 				{
 					printf_P(PSTR(ESC_FG_RED "Control Error (Set Interface).\r\n"
 					                         " -- Error Code: %d\r\n" ESC_FG_WHITE), ErrorCode);

LUFA/Drivers/USB/Class/Host/Printer.c

@@ -181,20 +181,12 @@ uint8_t PRNT_Host_SetBidirectionalMode(USB_ClassInfo_PRNT_Host_t* const PRNTInte
 	{
 		uint8_t ErrorCode;
 
-		USB_ControlRequest = (USB_Request_Header_t)
+		if ((ErrorCode = USB_Host_SetInterfaceAltSetting(PRNTInterfaceInfo->State.InterfaceNumber,
+		                                                 PRNTInterfaceInfo->State.AlternateSetting)) != HOST_SENDCONTROL_Successful)
 		{
-				.bmRequestType = (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE),
-				.bRequest      = REQ_SetInterface,
-				.wValue        = PRNTInterfaceInfo->State.AlternateSetting,
-				.wIndex        = PRNTInterfaceInfo->State.InterfaceNumber,
-				.wLength       = 0,
-			};
-
-		Pipe_SelectPipe(PIPE_CONTROLPIPE);
-
-		if ((ErrorCode = USB_Host_SendControlRequest(NULL)) != HOST_SENDCONTROL_Successful)
 			return ErrorCode;
 		}
+	}
 
 	return HOST_SENDCONTROL_Successful;
 }

LUFA/Drivers/USB/Core/AVR8/Host_AVR8.c

@@ -351,5 +351,22 @@ uint8_t USB_Host_ClearPipeStall(const uint8_t EndpointNum)
 	return USB_Host_SendControlRequest(NULL);
 }
 
+uint8_t USB_Host_SetInterfaceAltSetting(const uint8_t InterfaceNum,
+                                        const uint8_t AltSetting)
+{
+	USB_ControlRequest = (USB_Request_Header_t)
+		{
+			.bmRequestType = (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE),
+			.bRequest      = REQ_SetInterface,
+			.wValue        = AltSetting,
+			.wIndex        = InterfaceNum,
+			.wLength       = 0,
+		};
+
+	Pipe_SelectPipe(PIPE_CONTROLPIPE);
+
+	return USB_Host_SendControlRequest(NULL);
+}
+
 #endif
 

LUFA/Drivers/USB/Core/AVR8/Host_AVR8.h

@@ -330,6 +330,19 @@
 			 */
 			uint8_t USB_Host_ClearPipeStall(const uint8_t EndpointIndex);
 
+			/** Selects a given alternative setting for the specfied interface, via a SET INTERFACE standard request to
+			 *  the attached device.
+			 *
+			 *  \note After this routine returns, the control pipe will be selected.
+			 *
+			 *  \param[in] InterfaceIndex  Index of the interface whose alternative setting is to be altered.
+			 *  \param[in] AltSetting      Index of the interface's alternative setting which is to be selected.
+			 *
+			 *  \return A value from the \ref USB_Host_SendControlErrorCodes_t enum to indicate the result.
+			 */
+			uint8_t USB_Host_SetInterfaceAltSetting(const uint8_t InterfaceNum,
+													const uint8_t AltSetting);
+
 	/* Private Interface - For use in library only: */
 	#if !defined(__DOXYGEN__)
 		/* Macros: */

LUFA/Drivers/USB/Core/UC3/Host_UC3.c

@@ -351,5 +351,22 @@ uint8_t USB_Host_ClearPipeStall(const uint8_t EndpointNum)
 	return USB_Host_SendControlRequest(NULL);
 }
 
+uint8_t USB_Host_SetInterfaceAltSetting(const uint8_t InterfaceNum,
+                                        const uint8_t AltSetting)
+{
+	USB_ControlRequest = (USB_Request_Header_t)
+		{
+			.bmRequestType = (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE),
+			.bRequest      = REQ_SetInterface,
+			.wValue        = AltSetting,
+			.wIndex        = InterfaceNum,
+			.wLength       = 0,
+		};
+
+	Pipe_SelectPipe(PIPE_CONTROLPIPE);
+
+	return USB_Host_SendControlRequest(NULL);
+}
+
 #endif
 

LUFA/Drivers/USB/Core/UC3/Host_UC3.h

@@ -331,6 +331,19 @@
 			 */
 			uint8_t USB_Host_ClearPipeStall(const uint8_t EndpointIndex);
 
+			/** Selects a given alternative setting for the specfied interface, via a SET INTERFACE standard request to
+			 *  the attached device.
+			 *
+			 *  \note After this routine returns, the control pipe will be selected.
+			 *
+			 *  \param[in] InterfaceIndex  Index of the interface whose alternative setting is to be altered.
+			 *  \param[in] AltSetting      Index of the interface's alternative setting which is to be selected.
+			 *
+			 *  \return A value from the \ref USB_Host_SendControlErrorCodes_t enum to indicate the result.
+			 */
+			uint8_t USB_Host_SetInterfaceAltSetting(const uint8_t InterfaceNum,
+													const uint8_t AltSetting);
+
 	/* Private Interface - For use in library only: */
 	#if !defined(__DOXYGEN__)
 		/* Macros: */

LUFA/ManPages/ChangeLog.txt

@@ -11,7 +11,7 @@
   *  - Core:
   *   - Added USE_LUFA_CONFIG_HEADER compile time option to include a LUFAConfig.h header in the user director for LUFA configuration
   *     tokens as an alternative to tokens defined in the project makefile
-  *   - Added new RNDIS Device Classs Driver packet send and receive functions
+  *   - Added new USB_Host_SetInterfaceAltSetting() convenience function for the selection of an interface's alternative setting
   *  - Library Applications:
   *   - Added new MediaControl project
   *   - Added new incomplete AndroidAccessoryHost Host LowLevel demo
@@ -50,6 +50,7 @@
   *   - Internal restructuring for eventual multiple architecture ports
   *   - Added AVR32 UC3 architecture port (currently incomplete/experimental)
   *   - Added new architecture independant functions to enable, disable, save and restore the Global Interrupt Enable flags
+  *   - Added new RNDIS Device Classs Driver packet send and receive functions
   *  - Library Applications:
   *   - Added ability to write protect Mass Storage disk write operations from the host OS
   *   - Added new MIDIToneGenerator project