Epson Scan 2500 service manual USB Preventing Data Transfer TIME-OUT of Hosts, Interface Selection

EPSON Stylus Scan 2500								Revision A
USB						PREVENTING DATA TRANSFER TIME-OUT OF HOSTS
Standard		:based on				Generally, hosts abandon data transfer to peripherals when a peripheral is
		“Universal Serial Bus Specifications Revision 1.0”				continuously in the busy state for dozens of seconds. To prevent hosts from
		“Universal Serial Bus Device Class Definition for				entering this kind of time-out period, the printer slows down the data
		Printing Devices Version 1.0”				reception rate to around several bytes per minute, even if the printer is in the
Bit rate		:12Mbps (Full speed device)				busy state. This slowdown starts when the remaining open buffer area
						decreases to several hundred bytes. The Stylus Scan enters a continuous
Data encoding		:NRZI				busy state if the input buffer becomes full.
Adaptable connector		:USB series B
						INTERFACE SELECTION
Suggested cable length		:2 meters
						The Stylus Scan has two built-in interfaces; the USB and parallel interfaces.
	Table 1-7. USB Configuration					The interface in use is selected automatically.
								Automatic selection
Pin no.	Signal name	In/Out			Description
							When the Stylus Scan is turned on, it initializes and then goes into an idle
1	VCC	-	Cable power, max. power consumption is
			100mA				state. During this idle period the printer scans the interfaces for incoming
							data. The interface that receives data first is selected.
2	-Data	bi-directional	data
							When the host stops transferring data and the printer is in the stand-by
3	+Data	bi-directional	data, pull up to +3.3V via 1.5KΩ resistor
							state for a certain amount of time, the printer returns to the idle state. As
4	Ground	-	Cable ground				long as the host sends data or the printer interface is in the busy state, the
							interface selection does not change.
		Pin #2		Pin #1
								Interface status and selection
							When the parallel interface is not selected, the interface goes into the
							busy state. When the printer initializes or returns to the idle state, the
							parallel interface goes into the ready state. Be aware that an interrupt
							signal such as the -INIT signal only takes affect on the parallel interface
							when the parallel interface is selected.
							T
		Pin #3		Pin #4
	Figure 1-7. USB Pin Configuration
Product Description					Interfaces		T		20