The 8051 Microcontroller and Embedded

Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

HANEL

OTHER MODES OF THE 8255Printer Signal

(cont

’)

Data entry to the printer

is possible only when the

level of this signal is

“low”.(Internal fixing can be

carried out with DIP SW 1-

8. The condition at the

time of shipment is set

“low”for this signal.)

IN

SLCTIN

--

36

Pulled up to +5V dc thro

ugh 4.7 K ohms resistance.

--

--

35

Not used

--

NC

--

34

Same as with pin numbers 19 t0 30

--

GND

--

33

The level of this signal becomes

“low”when

printer is in

“paper end

”, “off-line

”, and error state

OUT

ERROR

--

32

When this signal becomes

“low”the printer con-

troller is reset to its initial state and the print buffer is cleared. Normally at

“high”

level; its pulse width

must be more than 50

μs at receiving terminal

IN

INIT

--

31

“Twisted-pair return

”signal; GND level

--

GND

--

19 –^30

Not used

--

NC

--

18

Printer chassis GND. In th

e printer, chassis GND

and the logical GND are is

olated from each other.

--

CHASISGND

--

17

Logic GND level

--

0V

--

16

Not used

--

NC

--

15

When the signal is at

”low”level, the paper is fed

automatically one line afte

r printing. (The signal

level can be fixed to

“low”with DIP SW pin 2-3

provided on the control circuit board.)

IN

AUTOFEEDXT

--

14

Description
Direction
Signal
Return
Table 15-3. Centronics Printer Specification (cont’)Serial