ST78C36/36A

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ECP/EPP PARALLEL PRINTER PORT WITH 16-BYTE FIFO

REV. 5.0.1

10

ECR Bits 7-5:

This field can be set to any value if the current value is 000 or 001. If the current value is not 000 or 001, then

the field can only be written to 000 or 001. The modes are defined as:

4.0

DEVICE OPERATION

4.1

SPP MODE

This is ECR mode 000 (system RESET mode).

In this output-only mode the host data is registered to PD[7:0] at the trailing edge of -IOW; PDIR is driven low;

-STROBE, -AUTOFD, INIT, and -SLCTIN are open-drain; and all timing is managed by the host through DSR

and DCR registers.

4.2

PS2 MODE

This is ECR mode 001.

In this bi-directional mode the host output data is registered to PD[7:0] at the trailing edge of -IOW, PDIR is

driven by DIR to allow peripheral data input, -AUTOFD, INIT, and -SLCTIN are totem-pole, and all timing is

managed by the host through DSR and DCR registers.

4.3

PPF MODE

This is ECR mode 010.

In this output-only mode the host data is written to the FIFO with I/O writes to address 400 or by DMA writes;

PDIR is driven low; -AUTOFD, INIT, and -SLCTIN are totem-pole.

FIFO data is automatically registered to PD[7:0] whenever the FIFO-E bit is low (data available), and timing is

generated by controller logic that handshakes -STROBE (controller) with BUSY (peripheral).

4.4

ECP MODE

This is ECR mode 011.

In this bi-directional mode the host data is written to the FIFO with I/O writes to address 000, 400 or DMA;

PDIR is driven by DIR (can only be set in ECR mode 001); -AUTOFD, INIT, and -SLCTIN are totem-pole. I/O

writes to address 000 will write a low into the FIFO tag bit, while I/O writes to address 400 or DMA will insert a

high.

4.4.1

ECP FORWARD MODE (PDIR = 0)

FIFO data is automatically registered to PD[7:0] whenever the FIFO-E bit is low (data available), and timing is

generated by controller logic that handshakes -STROBE (controller) with BUSY (peripheral). Data from the

FIFO tag bit is output on -AUTOFD after being registered simultaneous with FIFO data.

MODE

NAME

DESCRIPTION

000

SPP

Standard Centronics, output only. DCR bit-5 is forced to "0".

001

PS2

Bi-directional PS/2 parallel port. FIFO is disabled

010

PPF

FIFOed, output only. DCR Bit-5 is forced to “0”.

011

ECP

ECP FIFOed port with RLE de-compression. FIFO direction is controlled by DCR Bit-5.

100

EPP

EPP mode.

101

-

Reserved.

110

TST

FIFO test mode. FIFO is accessible via TFIFO register.

111

CFG

Configuration A/B register enable.