FDC37C669-MT datasheet(7/162 Pages) MICROCHIP

7 / 162 page

DESCRIPTION OF PIN FUNCTIONS

QFP/

TQFP

PIN NO.

NAME

SYMBOL

BUFFER

TYPE

DESCRIPTION

19,

37-40,

Interrupt Request

A, C, D,

E, F,

IRQ_A

IRQ_C

IRQ_D

IRQ_E

IRQ_F

O24

OD24

The interrupt request from the logical device

or IRQIN is output on one of the IRQA-G

signals.

Refer to the configuration registers

for more information.

If EPP or ECP Mode is enabled, this output is

pulsed low, then released to allow sharing of

interrupts.

Chip Select Input

nCS

When enabled, this active low pin serves as

an input for an external decoder circuit which

is used to qualify address lines above A10.

Reset

RESET

This active high signal resets the chip and

must be valid for 500 ns minimum. The effect

on the internal registers is described in the

appropriate

section.

The

configuration

registers are not affected by this reset.

FLOPPY DISK INTERFACE

nRead Disk Data

nRDATA

Raw serial bit stream from the disk drive, low

active.

Each falling edge represents a flux

transition of the encoded data.

nWrite

Gate

nWGATE

OD48

This active low high current driver allows

current to flow through the write head.

becomes active just prior to writing to the

diskette.

nWrite

Data

nWDATA

OD48

This active low high current driver provides the

encoded data to the disk drive. Each falling

edge causes a flux transition on the media.

nHead

Select

nHDSEL

OD48

This high current output selects the floppy disk

side for reading or writing. A logic "1" on this

pin means side 0 will be accessed, while a

logic "0" means side 1 will be accessed.

Direction

Control

nDIR

OD48

This high current low active output determines

the direction of the head movement. A logic

"1" on this pin means outward motion, while a

logic "0" means inward motion.

FDC37C669-MT Datasheet(PDF) 7 Page - Microchip Technology

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