Lucent Technologies USS-720 Printer Class-Specific Requests, Get Port Status Data Bit Description

USS-720Instant USB	Preliminary Data Sheet, Rev. 5
USB-to-IEEE1284 Bridge	September 1999

USB Port (continued)

Printer Class-Specific Requests

Printer class-specific requests supported by the USS-720 are listed in Table 15.

Table 15. Class-Specific Requests

Label	bmRequestType	bRequest	wValue	wIndex	wLength	Data
GET_DEVICE_ID	10100001B	0	Config	Interface and	Maximum	IEEE 1284 Device
			Index	Alternate Setting	Length	ID String
GET_PORT_STATUS	10100001B	1	Zero	Interface	1	BYTE
SOFT_RESET	00100011B	2	Zero	Interface	Zero	[None]

GET_DEVICE_ID

This request returns an IEEE 1284 Device ID string. This command is supported by all three alternate inter- face settings.

The Device ID is a length field followed by a case- sensitive string of ASCII characters. The first 2 bytes are the length of the sequence, including the two length bytes. The first byte is the most significant; length values of 0000h, 0001h, and 0002h are reserved.

Following the two length bytes, the sequence is composed of a series of keys and values of the form:

key: value {, value};

repeated for each key. As indicated, each key will have one value, and may have more than one value. The minimum necessary keys are MANUFACTURER, COMMAND SET, and MODEL (case sensitive). These keys may be abbreviated as MFG, CMD, and MDL. Each key (and each value) is a string of characters. Any characters except colon (:), comma (,), and semi- colon (;) may be included as part of the key or value string. Any leading or trailing white space in the string is ignored by the parsing program, but is still counted as part of the overall length of the sequence.

For more details, see IEEE 1284-1994, Section 7.6.

Note: The USS-720 satisfies this request by requesting Device ID data from the attached IEEE 1284 peripheral. If the peripheral does not support Device ID, the USS-720 will return a zero-length data packet to the host.

GET_PORT_STATUS

This request returns the current status of the printer. Table 16 defines the data returned and describes the format of the status data. This command is only sup- ported by the two printer class-specific alternate inter- face settings (0 and 1). Attempts to issue this command to interface 0, alternate setting 2 will result in a stall.

Table 16. Get Port Status Data

Bit	Description
7—6	Reserved, will always read 0.
5	Paper error.
4	Select.
3	Not error: 0 = error, 1 = no error.
2—0	Reserved, will always read 0.

SOFT_RESET

This request flushes all buffers and resets the Bulk Out and Bulk In pipes to their default states, and also resets all parallel port hardware and registers to their default state. This command is supported in all three alternate interface settings.

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