Epson Stylus Photo 720, Service Manual

Page: 15 / 154

EPSON Stylus Photo 720 / EPSON Stylus Photo EX3 Revision A
Product Description Interface Specification 15
Following lists “Notes” when using the parallel interface.
o
“Return GND pin” in the table means twist pair return and is connected to the
signal GND level.
For each signal, use the twist pair wire and connect the return side.
Also, these cables are shielded wires and it is effective means to connect to each
chassis GND in the center machine and printer for electrostatic noise.
o
Conditions for interface are all based on TTL level. Rise and fall time should be
within 0.2
µ
s.
o
Refer to the timing chart for transmission timing of each signals.
o
Do not perform data transmission ignoring -ACK or BUSY signals. (Perform the
data transmission after confirming that either -ACK or BUSY signal is Low)
o
It is possible to perform the printing test including interface circuit without using
external equipment when 8-bit data signal (2-9 pin) is set to appropriate character
code (against GND, Open=”1”, Short=”0”) and connect then forcefully to -ACK
and -STRB. However, to perform this, “I/F selection” of EEPROM must be set to
“Auto”. Also, IEEE-1284.4 packet mode must be set Off.
The figure below shows the timing chart of the parallel interface.
Figure 1-4. Timing Chart
On the above timing chart, T
act
rated period is shown below.
14 30 HostBusy PC Host busy signal.
31 30 -INIT PC Not used.
32 29
-DataAvail/
DataBit-0,4
Printer
Data available signal and reverse channel
transfer data bit 0 or 4.
36 30 1284-Active PC 1284 active signal.
18 - Logic H Printer Pulled up to +5V via 3.9K ohm resistor.
35 - +5V Printer Pulled up to +5V via 3.3 K ohm resistor.
17 - Chassis - Printer chassis GND.
16, 33
19-30
- GND - Twist pair return GND.
15, 34 - NC - Not used.
Table 1-6. Connector Pin Assignment and Signals (F-Channel)
Pin No.
Return
GND Pin
Signal Name From Function Description
Table 1-7. t
act
Rated Period
Parallel I/F Mode T
act
Rated Period
High speed (default) 0.5
µ
s
Normal speed 2
µ
s
Data byte n Data byte n+1
DATA
/STROBE
BUSY
/ACKNLG
t
hold
t
setup
t
ready
t
stb
t
busy
t
reply
t
ack
t
nbusy
t
next
timechart