Intel IXP400 manual IxUSB Error Handling, Stall on OUT Transactions

Intel® IXP400 Software

Access-Layer Components: USB Access (ixUSB) API

Figure 103. STALL on OUT Transactions

Host
	Device
OUT	Data
	STALL
	Bus
Request	Reply
	B2419-01

The second case of a STALL handshake is known as a “protocol stall” and is unique to control pipes. Protocol stall differs from functional stall in meaning and duration.

A protocol STALL is returned during the Data or Status stage of a control transfer, and the STALL condition terminates at the beginning of the next control transfer (Setup). Protocol stalls are usually sent to notify the host that a particular USB command is malformed or not implemented.

22.4.4ixUSB Error Handling

The USB API calls return the IX_FAIL error code after detecting errors. It is the responsibility of the user to implement appropriate error handling.

Detailed error codes are used to report USB Driver errors. They are provided in the lastError field of the USBDevice structure that must be passed by the user in every API call. When the API calls are successful the lastError field is assigned the IX_SUCCESS value.

April 2005	IXP400 Software Version 2.0	Programmer’s Guide
306	Document Number: 252539, Revision: 007