Appendixes

Interfaces

Parallel Interface

Specifications

Transmission mode

8-bit parallel data

 

 

Receive buffer size

16kB

 

 

Transmission modes

Compatible mode

 

It is an asynchronous forward direction of the byte width

 

(from host to printer) channel, and the interface line of

 

the data is operated in accordance with signal line

 

definitions of Centronics.

 

NIBBLE mode

 

Nibble mode is asynchronous reverse channel

 

communication with data transmission controlled by the

 

host computer. In reverse channel transmission, the data is

 

nibble transmitted in two parts using four status lines (Fault,

 

Select, PE, and Busy). And nibble mode can be used along

 

with compatible mode to send data in two directions.

 

ECP mode

 

ECP mode permits bi-directional asynchronous data

 

transmission, and thanks to its interlock handshake, it does

 

not require the timing necessary with compatible mode.

 

 

Signal level

IEEE1284 standard

 

 

Signal line and pin assignment table

Pin No.

Signal name

I/O

Function

1

*STROBE

Input

Strobe signal to read in 8-bit data

 

 

 

 

2-9

DATA1-8

Input

8-bit parallel signal

 

 

 

 

10

*ACKNLG

Output

8-bit data request signal

11

BUSY

Output

Signal specifying printer busy

 

 

 

 

12

PERROR

Output

Signal specifying media out

 

 

 

 

13

SELECT

Output

Signal specifying if the printer is on-line (printing

 

 

 

enabled) or off-line (pausing)

 

 

 

 

14

AUTOFD

Input

Invalid (ignored)

 

 

 

 

15

NC

---

Not used

 

 

 

 

16

GND

---

Signal ground

 

 

 

 

17

FGND

---

Frame ground

18

P.L.H

Output

Peripheral logic high (pull up to +5V at 1kΩ)

 

 

 

 

19-30

GND

---

Ground for twisted pair return

 

 

 

 

31

*INIT

Input

Printer reset

 

 

 

 

32

*FAULT

Output

Signal specifying printer error

 

 

 

 

33-35

NC

---

Not used

 

 

 

 

36

SELECTIN

Input

Invalid (ignored)

 

 

 

 

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