Programming Model

Printer Port Control Register

ADR/SIZ

 

 

 

$FFF42037

(8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

7

6

5

 

4

 

3

 

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

NAME

 

 

 

 

DOEN

 

INP

 

STB

FAST

MAN

 

 

 

 

 

 

 

 

 

 

 

 

OPER

R

R

R

 

R/W

 

R/W

 

R/W

R/W

R/W

 

 

 

 

 

 

 

 

 

 

 

 

RESET

0

0

0

 

0 PL

 

0 PL

 

0 PL

0 PL

0 PL

 

 

 

 

 

 

 

 

 

 

 

 

MAN

Manual Strobe Control - This bit selects the auto or

 

manual mode for the printer strobe. When this bit is low,

 

the printer strobe is generated automatically by a write to

 

the Printer Data Register (auto mode). When this bit is

 

high, the strobe pin is directly controlled by the STB

 

control bit (manual mode).

FAST

Strobe Timing - In auto mode, this bit controls the printer

 

strobe timing. When this bit is low, the strobe time is 212

 

BCLK periods (10.6 μs at 20MHz, 8.5 μs at 25MHz and

 

6.4 μs at 33MHz). When this bit is high, the strobe time is

 

50 BCLK periods (2.5 μs at 20MHz, 2 μs at 25MHz and

 

1.5 μs at 33MHz). Note that the strobe time is the width of

 

the low-going pulse generated on the STB* pin. Also note

 

that after a write to the Printer Data Register, the

 

PCCchip2 delays about one strobe time before issuing the

 

STB* pulse. This bit is not used in manual mode.

Note

The PCCchip2 runs at half the MPU speed on the

 

MVME177P. For example, an MVME177P with a 50 MHz

 

MPU will run the PCCchip2 at 25 MHz.

STB

Manual Strobe Control - In the manual mode, the software

 

controls the strobe timing. When this bit is high, the

 

printer strobe is activated. When this bit is low, the printer

 

strobe is not activated. This bit has no function in auto

 

mode.

3

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Motorola MVME1X7P manual Printer Port Control Register, Man, Stb