97CFDC Datasheet, PDF (7/20 Pages) SMSC Corporation – USB FLOPPY DISK CONTROLLER

BLOCK DIAGRAM
To USB Bus
High Speed
USB
XCVR
Serial Interface Engine
End Point
Control
Option
Select/
Drive
Control
Flash/
SRAM
Interface
nMEMEN
nOPTEN
nDRVRDY
nFDPWR
nFRD
nFCE
GPIO
DRIVE
INTERFACE
nTRK0, nINDEX,
nWRTPRT, nDSKCHG
nRDATA, DRVDEN0,
DRVDEN1, nWDATA,
nWGATE, nHDSEL,
nDIR, nMTR0, nDS0,
nSTEP
CLOCK
CONTROL
FD[7:0]
FA[15:0]
SIE DMA
RX/
TX
Queue
8051 CPU
IRQ0
FLOPPY DISK
CONTROLLER
DRQ2
TC
nDAK2
nIOW
nIOR
nCE
Memory
Management
Unit
Map RAM
Arbiter
8237
4k Data Buffer RAM
ADDRESS
DECODE
AEN
SA[13:0]
nMEMW
nMEMR
SD[7:0]
SRAM
Interface
Pin Descriptions
PIN NO.
75
69
71
67
68
76
NAME
Read Disk
Data
Write
Data
Head
Select
Direction
Control
Step Pulse
Disk Change
BUFFER
SYMBOL
TYPE
DESCRIPTION
FLOPPY DISK INTERFACE
nRDATA
IS Raw serial bit stream from the disk drive, low
active. Each falling edge represents a flux
transition of the encoded data.
nWDATA
OD12 This active low high current driver provides the
encoded data to the disk drive. Each falling edge
causes a flux transition on the media.
nHDSEL
OD12
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.
nDIR
OD12
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.
nSTEP
OD12 This active low high current driver issues a low
pulse for each track-to-track movement of the
head.
nDSKCHG
IS This input senses that the drive door is open or
that the diskette has possibly been changed since
the last drive selection.
SMSC DS – USB97CFDC
Page 7
Rev. 12/15/2000