Prevention Of Data Transfer Time-Out; Automatic Interface Selection - Epson Stylus Photo 870 Service Manual

EPSON Stylus Photo 870/1270
Table 6-12. Pin Assignments and Signals (Reverse Channel)
Pin Return
Signal
no. GND pin
17 Chassis —
GND
16,33, GND —
19-30
15,34 NC —
* In/Out refers to the direction of the signal from the printer's point of view.
6.9.14.3 USB Interface
! Standard:
Based on:
Universal Serial Bus Specifications Rev. 1.0
Universal Serial Bus Device Class Definition
for Printing Devices Version 1.0
! Bit rate:
12 Mbps (full speed device)
! Data encoding:
NRZI
! Adaptable connector: USB Series B
! Cable length:
Maximum 6.5 feet (2 meters)
recommended
Table 6-13. Pin Assignments and Signals (USB Connector)
Pin no. Signal In/Out
1 VCC —
2 -Data Bi-D
3 +Data Bi-D
4 Ground —
In/Out Description
— Chassis GND
— Signal GND
— Not connected
Description
Cable power (maximum power
consumption is 2 mA)
Data
Data, pull up to +3.3 V via 1.5K ohm
resistor
Cable ground
Pin #2
Pin #3
Figure 6-22. USB Pin Assignments

6.9.15 Prevention of Data Transfer Time-out

Generally, hosts abandon data transfer to peripherals when the
peripheral is continuously busy for several seconds. To prevent this
kind of time-out, the printer can receive data slowly (several bytes per
minute). The slowdown starts when the input buffer reaches several
hundred of bytes. The printer enters a continuously busy state when
the input buffer is full.
USB (using a parallel to USB adapter) and IEEE1284.4 on the parallel
interface do not use this function.

6.9.16 Automatic Interface Selection

The EPSON Stylus Photo 870/1270 each have two built-in interfaces:
USB and parallel.
! Automatic Selection
In automatic interface selection, the printer waits to receive data
and selects the interface that receives data first. When the host
stops transferring data and the printer is in stand-by for several
seconds, the printer returns to the waiting state. As long as the
host sends data or the printer interface is busy, the selected
interface remains the same.
Chapter 7 Appendix
Pin #1
Pin #4
107