Lucent Technologies USS-720 IOCTL1284 ECPSETCHANNEL, 4 I/O Control Codes continued, February

USS-720	Preliminary User Guide, Rev. 2
USB Device Driver	February 1999

4 I/O Control Codes (continued)

4.3 IOCTL_1284_ ECP_SET_CHANNEL

IOCTL_1284_ ECP_SET_CHANNEL sets the ECP channel on the peripheral for reads and writes. Details regarding parameters and error codes follow.

4.3.1 Parameters

lpInBuffer—Points to a buffer that contains a single byte which specifies the ECP channel to be set.

nInBufferSize—Specifies the size (in bytes) of the buffer pointed to by lpInBuffer. For this operation, this value should be 1.

lpOutBuffer—Points to an output buffer. Not used with this operation. Set to NULL.

nOutBufferSize—Specifies the size (in bytes) of the buffer pointed to by lpOutBuffer. Not used with this operation. Set to zero.

lpBytesReturned—Points to a DWORD that receives the actual size (in bytes) of the data stored into lpOutBuffer. Not used with this operation.

4.3.2 Notes

Requires that the register-based mode be successfully set to ECP_REGISTER_MODE or

ECP_RLE_REGISTER_MODE (see USS-720USB-to-IEEE 1284 Bridge Preliminary Data Sheet, “Register-Based Operation” and Section 4.4, IOCTL_1284_SET_MODE, of this document).

4.3.3 Error Codes

ERROR_INVALID_ALTERNATESETTING—This command is only supported in ALT_INTERFACE_2 (see Section 4.9 of this document).

STATUS_IO_DEVICE_ERROR—Negotiation failed.

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