Epson Stylus Photo 720 Service Manual page 15

EPSON Stylus Photo 720 / EPSON Stylus Photo EX3
Table 1-6. Connector Pin Assignment and Signals (F-Channel)
Return
Pin No. Signal Name
GND Pin
14 30 HostBusy
31 30 -INIT
-DataAvail/
32 29
DataBit-0,4
36 30 1284-Active
18 - Logic H
35 - +5V
17 - Chassis
16, 33
- GND
19-30
15, 34 - NC
Following lists "Notes" when using the parallel interface.
"Return GND pin" in the table means twist pair return and is connected to the
o
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.
Conditions for interface are all based on TTL level. Rise and fall time should be
o
µ
within 0.2 s.
Refer to the timing chart for transmission timing of each signals.
o
Do not perform data transmission ignoring -ACK or BUSY signals. (Perform the
o
data transmission after confirming that either -ACK or BUSY signal is Low)
It is possible to perform the printing test including interface circuit without using
o
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.
Product Description
From Function Description
PC Host busy signal.
PC Not used.
Data available signal and reverse channel
Printer
transfer data bit 0 or 4.
PC 1284 active signal.
Printer Pulled up to +5V via 3.9K ohm resistor.
Printer Pulled up to +5V via 3.3 K ohm resistor.
- Printer chassis GND.
- Twist pair return GND.
- Not used.
DATA
/STROBE
BUSY
t
ready
/ACKNLG
On the above timing chart, T
Parallel I/F Mode
High speed (default)
Normal speed
Interface Specification
Data byte n
t
hold
t
t
setup stb
t
busy
t
reply
Figure 1-4. Timing Chart
rated period is shown below.
act
Table 1-7. t Rated Period
act
T Rated Period
act
0.5
2
Revision A
Data byte n+1
t
next
t t
ack nbusy
timechart
µ
s
µ
s
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