User`s guide

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.
3DATA1 21 In
4DATA2 22 In
5DATA3 23 In
6DATA4 24 In
7DATA5 25 In
8DATA6 26 In
9DATA7 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