Data transmission
timing:
Refer to the IEEE-1284 specification
Extensibility request:
The printer responds to the extensibility
request in the affirmative when the
request is 00H or 04H, which means:
00H: Request nibble mode of reverse
channel transfer
04H: Request device ID in nibble mode of
reverse channel transfer
Reverse channel pin assignments
Pin
no.
Signal name
GND
In/Out*
Description
1
HostClk
19
In
Strobe pulse. Input data is
latched at falling edge of
the signal.
2
DATA0
20
In
These signals represent
information in bits 0 to 7 of
parallel data respectively.
Each signal is at HIGH level
when data is logical 1 and
LOW when it is logical 0.
These signals are used to
transfer the 1284 extensibility
request values to the printer.
3
DATA1
21
In
4
DATA2
22
In
5
DATA3
23
In
6
DATA4
24
In
7
DATA5
25
In
8
DATA6
26
In
9
DATA7
27
In
10
PtrClk
28
Out
Used to qualify data being
sent to the host. Set LOW
then HIGH to cause an
interrupt indicating to host
that data is available.
11
PtrBusy/
DataBit-3,7
29
Out
Data bits 3 then 7 indicate
forward channel busy status.
12
ACkDataReq/
DataBit-2,6
28
Out
Data bits 2 then 6. Set HIGH
until host requests data
transfer, then follows
n
Data Avail (
n
Fault).
13
Xflag/
DataBit-1,5
28
Out
X flag signal and reverse
channel transfer data bits 1
then 5.
A-12
Technical Specifications
