PC87351 datasheet(19/86 Pages) NSC

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1.0 Signal/Pin Connection and Description (Continued)

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1.4.4

General-Purpose Input/Output (GPIO) Ports

STEP

OD24, O4/24

Step. Issues pulses to the disk drive at a software programmable rate to

move the head during a seek operation.

This pin provides an additional step signal in PPM mode when PNF = 0.

TRK0

INT

Track 0. Indicates to the controller that the head of the selected floppy

disk drive is at track 0.

This pin provides an additional Track 0 signal in PPM Mode when PNF = 0.

WDATA65

OD24, O4/24

Write Data. Carries out the write pre-compensated serial data that is

written to the selected floppy disk drive. Pre-compensation is software

selectable.

This pin provides an additional WDATA signal in PPM mode when PNF = 0.

WGATE

OD24, O4/24

Write Gate. Enables the write circuitry of the selected disk drive. WGATE

is designed to prevent glitches during power up and power down. This

prevents writing to the disk when power is cycled.

This pin provides an additional WGATE signal in PPM mode when PNF = 0.

INT

Write Protected. Indicates that the disk in the selected drive is write

protected. A software programmable conﬁguration bit (FDC conﬁguration

at Index F0h, Logical Device 0) can force an active write-protect indication

to the FDC regardless of the status of this pin.

This pin provides an additional WP signal in PPM mode when PNF = 0.

Signal

Pin/s

I/O

Buffer Type

Description

GPIO17

GPIO16-10

43-37

I/O

INTS/

OD12, O6/12

General-Purpose I/O Port 1, bits 0-7. Each pin is configured independently

as input or I/O, with or without static pull-up, and with either open-drain or to-

tem-pole output type. The port support interrupt assertion and each pin can

be enabled or masked as interrupt source.

GPIO 16-10 119-117,

115-112

These pins provide alternate GPIO location options.

GPIO22-20 128,

127, 99

I/O

INTS/

OD12, O6/12

General-Purpose I/O Port 2, bits 0-2. Same as Port 1.

Signal

Pin/s

I/O

Buffer Type

Description

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