Avago Technologies LSI53C320 - Manual (Page 39)

Interface Control Signals 3-5
Version 2.2 Copyright © 2003 by LSI Logic Corporation. All rights reserved.
3.3 Interface Control Signals
Table 3.3 describes the interface control signals for the LSI53C320. The
LSI53C320 requires an external POR, which is implemented using the
CHIP_RESET/ signal.
Figure A.1 provides an example external POR
circuit.
Table 3.3 Chip Interface Control Signals
Signal Name Pin Type Description
CHIP_RESET/ C10 I The active LOW Master Reset signal provides a general purpose
chip reset that forces the internal elements of the LSI53C320 to a
known state. Asserting this signal places the LSI53C320 state
machine in an idle state and places all controls in a passive state.
The minimum CHIP_RESET/ asserted pulse width is 100 ns.
WS_ENABLE/ A7 I The Active LOW Warm Swap Enable signal enables and disables
SCSI transfers through the LSI53C320. The WS_ENABLE/ input
removes the chip from an active bus without disturbing the current
SCSI transaction. When Warm Swap Enable asserts, the
LSI53C320 3-states the SCSI signals after it detects the next bus
free state. The LSI53C320 no longer passes on signals until the
WS_ENABLE/ pin deasserts and both SCSI buses enter the Bus
Free state.
XFER_ACTIVE A8 O The Transfer Active signal enables and disables SCSI transfers
through the LSI53C320. The LSI53C320 asserts this signal when
the chip is active to indicate that the chip completed its internal
testing, the SCSI bus has entered a bus free state, or that SCSI
traffic can now pass from one side of the chip to the other side of
the chip. The LSI53C320 deasserts this signal to detect a Bus
Free state due to the WS_ENABLE/ signal being LOW.
Deasserting this signal disables transfers through the device.
CLOCK A9 I CLOCK provides the 40 MHz oscillator input to the LSI53C320. It
is the clock source for the protocol control state machines and
timing generation logic. The bus signal transfer paths do not use
this clock.
BSY_LED B9 O The Busy LED signal provides an 8 mA SCSI activity LED output.
The LSI53C320 asserts this signal to indicate SCSI bus activity.