ZILOG Z0538001VSC

ZILOG
Z5380 SCSI
PRODUCT SPECIFICATION
Z5380 SCSI
SMALL COMPUTER
SYSTEM INTERFACE (SCSI)
FEATURES
■
Pin Compatible with the Industry Standard 5380
■
Supports Target and Initiator Roles
■
40-Pin DIP or 44-Pin PLCC Package Styles
■
Arbitration Support
■
Low-Power CMOS
■
DMA or Programmed I/O Data Transfers
■
Asynchronous Interface (Supports 1.5 MB/s)
■
Supports Normal or Block Mode DMA
■
Direct SCSI Bus Interface with On-Board 48 mA Drivers
■
Memory or I/O Mapped CPU Interface
GENERAL DESCRIPTION
The Z5380 SCSI (Small Computer System Interface) controller is designed to implement the SCSI protocol as
defined by the ANSI X3.131-1986 standard, and is fully
compatible with the industry standard 5380. It is capable
of operating both as a Target and as an Initiator. Special
high-current open-drain outputs enable the Z5380 to directly interface to, and drive, the SCSI bus. The Z5380 has
the necessary interface hook-ups which allows the system
CPU to communicate with it like any other peripheral
device. The CPU can read from, or write to, the SCSI
registers which are addressed as standard or memorymapped I/Os (Figure 1).
The Z5380 increases the system performance by minimizing the CPU intervention in DMA operations which the SCSI
controls. The CPU is interrupted by the SCSI when it
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detects a bus condition that requires attention. It also
supports arbitration and reselection. The Z5380 has the
proper hand-shake signals to support normal and block
mode DMA operations with most DMA controllers available (Figure 2).
Notes:
All Signals with a preceding front slash, "/", are active Low, e.g.,
B//W (WORD is active Low); /B/W (BYTE is active Low, only).
Power connections follow conventional descriptions below:
Connection
Circuit
Device
Power
Ground
VCC
GND
VDD
VSS
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Z5380 SCSI
GENERAL DESCRIPTION (Continued)
/DB7-/DB0,
/DBP
/ACK
/ATN
/BSY
/MSG
I//O
C//D
/REQ
/RST
/SEL
48 mA SCSI Transceivers
/IOR
/IOW
Interface
Control
Logic
Data
Input
Register
Data
Output
Register
DMA
Logic
Interrupt
Logic
Control
Registers
/CS
/RESET
CPU BUS
Interface
IRQ
READY
DRQ
/DACK
D7-D0
/EOP
A2-A0
Figure 1. Z5380 Block Diagram
D7-D0
/DB7-DB0, /DBP
A2-A0
/ACK
/IOR
/ATN
/IOW
/BSY
/CS
/MSG
/RESET
/DACK
Z5380
I//O
C//D
/EOP
/REQ
DRQ
/RST
READY
/SEL
IRQ
GND
VDD
Figure 2. Logic Symbol
2
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N/C
2
1 44 43 42 41 40
D5
D0
3
D4
/DB7
4
D3
/DB6
5
D2
/DB5
6
D1
/DB4
Z5380 SCSI
D0
1
40
D1
/DB7
2
39
D2
/DB6
3
38
D3
/DB5
4
37
D4
/DB3
7
39
D6
/DB4
5
36
D5
/DB2
8
38
D7
/DB1
9
37
A2
/DB3
6
35
D6
/DB2
7
34
D7
/DB0
10
36
A1
11
35
VDD
/DB1
8
33
A2
/DBP
/DB0
9
32
A1
GND
12
34
N/C
31
VDD
GND
13
33
A0
30
A0
/RESET
/ACK
14
27
/EOP
/ATN
15
26
/DACK
/RST
16
25
READY
I//O
17
24
/IOR
C//D
18
23
IRQ
/MSG
19
22
DRQ
/REQ
20
21
/CS
/EOP
/ATN
17
29
18 19 20 21 22 23 24 25 26 27 28
/DACK
RDY
28
30
IRQ
13
16
/IOR
/BSY
/RESET
/ACK
/CS
/IOW
/IOW
31
DRQ
29
32
15
N/C
12
14
/REQ
/SEL
/SEL
/BSY
C//D
11
/MSG
GND
Z5380
I//O
10
/RST
/DBP
Z5380
Figure 3b. 44-Pin PLCC Pin Configuration
Figure 3a. 40-Pin DIP Pin Configuration
PIN DESCRIPTION
Microprocessor Bus
Figure 3 shows the pins and their respective functions for
both the DIP and PLCC.
A2-A0 Address Lines (Input). Address lines are used with
/CS, /IOR, or /IOW to address all internal registers.
/CS Chip Select (Input, Active Low). This signal, in conjunction with /IOR or /IOW, enables the internal register
selected by A2-A0, to be read from or written to.
/DACK DMA Acknowledge (Input, Active Low). /DACK
resets DRQ and selects the data register for input or output
data transfers. /DACK is used by DMA controller instead of
/CS.
DRQ DMA Request (Output, Active High). DRQ indicates
that the data register is ready to be read or written. DRQ is
asserted only if DMA mode is set in the Command Register. DRQ is cleared by /DACK.
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D7-D0 Data Lines (Bi-directional, three-state, Active High).
Bi-directional microprocessor data bus lines. D0 is the
Least Significant Bit of the bus. Data bus lines carry data
and commands to and from the SCSI.
/EOP End of Process (Input, Active Low). /EOP is used to
terminate a DMA transfer. If asserted during a DMA cycle,
the current byte will be transferred, but no additional bytes
will be requested.
/IOR I/O Read (Input, Active Low). /IOR is used in conjunction with /CS and A2-A0 to read an internal register. It also
selects the Input Data Register when used with /DACK.
/IOW I/O Write (Input, Active Low). /IOW is used in conjunction with /CS and A2-A0 to write an internal register. It also
selects the Output Data Register when used with /DACK.
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Z5380 SCSI
PIN DESCRIPTION (Continued)
IRQ Interrupt Request (Output, Active High). IRQ alerts a
microprocessor of an error condition or an event completion.
READY Ready (Output, Active High). Ready is used to
control the speed of Block Mode DMA transfers. This
signal goes active to indicate the chip is ready to send/
receive data and remains Low after a transfer until the last
byte is sent or until the DMA Mode bit is reset.
/RESET Reset (Input, Active Low). /RESET clears all registers. It has no effect upon the SCSI /RST signal.
/DB7-/DB0, /DBP Data Bus Bits, Data Bus Parity Bit (Bidirectional, Open-drain). These eight data bits (/DB7-/
DB0), plus a parity bit (/DBP) form the data bus. /DB7 is the
most significant bit (MSB) and has the highest priority
during the Arbitration phase. Data parity is odd. Parity is
always generated and optionally checked. Parity is not
valid during Arbitration.
I//O Input/Output (Bi-directional, Open-drain). I/O is a
signal driven by a Target which controls the direction of
data movement on the SCSI bus. True indicates input to the
Initiator. This signal is also used to distinguish between
Selection and Reselection phases.
SCSI Bus
The following signals are all bi-directional, active Low,
open-drain, with 48 mA sink capability. All pins interface
directly with the SCSI bus.
/ACK Acknowledge (Bi-directional, Open-drain, Active
Low). Driven by an Initiator, /ACK indicates an acknowledgment for a /REQ//ACK data-transfer handshake. In the
Target role, /ACK is received as a response to the /REQ
signal.
/ATN Attention (Bi-directional, Open-drain, Active Low).
Driven by an Initiator, received by the Target, /ATN indicates an Attention condition.
/MSG Message (Bi-directional, Open-drain, Active Low).
This signal is driven by the Target during the Message
phase. This signal is received by the Initiator.
/REQ Request (Bi-directional, Open-drain, Active Low).
Driven by the Target and received by the Initiator, this
signal indicates a request for a /REQ//ACK data-transfer
handshake.
/RST SCSI Bus Reset (Bi-directional, Open-drain, Active
Low). This signal indicates a SCSI bus Reset condition.
/SEL Select (Bi-directional, Open-drain, Active Low). This
signal is used by an Initiator to select a Target, or by a
Target to reselect an Initiator.
/BSY Busy (Bi-directional, Open-drain, Active Low). This
signal indicates that the SCSI bus is being used and can
be driven by both the Initiator and the Target device.
C//D Control/Data (Bi-directional, Open-drain). Driven by
the Target and received by the Initiator, C//D indicates
whether Control or Data information is on the Data Bus.
True indicates Control.
FUNCTIONAL DESCRIPTION
The Z5380 Small Computer System Interface (SCSI) has a
set of eight registers that are controlled by the CPU. By
reading and writing the appropriate registers, the CPU
may initiate any SCSI Bus activity or may sample and
assert any signal on the SCSI Bus. This allows the user to
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implement all or any of the SCSI protocol in software. These
registers are read (written) by activating /CS with an
address on A2-A0 and then issuing an /IOR (/IOW) pulse.
This section describes the operation of the internal registers (Table 1).
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Z5380 SCSI
Table 1. Register Summary
A2
Address
A1 A0
Address: 0
(Read Only)
D7 D6 D5 D4 D3 D2 D1 D0
R/W
Register Name
0
0
0
0
0
0
0
1
0
0
1
0
R
W
R/W
R/W
Current SCSI Data
Output Data
Initiator Command
Mode
0
1
1
1
1
0
0
0
1
0
0
1
R/W
R
W
R
Target Command
Current SCSI Bus Status
Select Enable
Bus and Status
1
1
1
1
1
0
1
1
1
1
1
0
0
1
1
W
R
W
R
W
/DB0
/DB1
/DB2
/DB3
/DB4
/DB5
/DB6
/DB7
Start DMA Send
Input Data
Start DMA Target Receive
Reset Parity/Interrupt
Start DMA Initiator Receive
Figure 4. Current SCSI Data Register
Address: 0
(Write Only)
D7 D6 D5 D4 D3 D2 D1 D0
Data Registers
The data registers are used to transfer SCSI commands,
data, status, and message bytes between the microprocessor Data Bus and the SCSI Bus. The Z5380 does not
interpret any information that passes through the data
registers. The data registers consist of the transparent
Current SCSI Data Register, the Output Data Register, and
the Input Data Register.
/DB0
Current SCSI Data Register. Address 0 (Read Only). The
Current SCSI Data Register (Figure 4) is a read-only
register which allows the microprocessor to read the active
SCSI Data Bus. This is accomplished by activating /CS
with an address on A2-A0 of 000 and issuing an /IOR pulse.
If parity checking is enabled, the SCSI Bus parity is
checked at the beginning of the read cycle. This register
is used during a programmed I/O data read or during
Arbitration to check for higher priority arbitrating devices.
Parity is not guaranteed valid during Arbitration.
/DB6
Output Data Register. Address 0 (Write Only). The Output
Data Register (Figure 5) is a write-only register that is used
to send data to the SCSI Bus. This is accomplished by
either using a normal CPU write, or under DMA control, by
using /IOW and /DACK. This register also asserts the
proper ID bits on the SCSI Bus during the Arbitration and
Selection phases.
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/DB1
/DB2
/DB3
/DB4
/DB5
/DB7
Figure 5. Output Data Register
Initiator Command Register. Address 1 (Read/Write).
The Initiator Command Register (Figures 6 and 7) are read
and write registers which assert certain SCSI Bus signals,
monitors those signals, and monitors the progress of bus
arbitration. Many of these bits are significant only when
being used as an Initiator; however, most can be used
during Target role operation.
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Z5380 SCSI
FUNCTIONAL DESCRIPTION (Continued)
Address: 1
(Read Only)
D7 D6 D5 D4 D3 D2 D1 D0
Assert Data Bus
Assert /ATN
Assert /SEL
This bit should also be set during DMA send operations.
Bit 1. Assert /ATN. /ATN may be asserted on the SCSI Bus
by setting this bit to a one (1) if the Target Mode bit (Mode
Register, bit 6) is False. /ATN is normally asserted by the
initiator to request a Message Out bus phase. Note that
since Assert /SEL and Assert /ATN are in the same register,
a select with /ATN may be implemented with one CPU
write. /ATN may be deasserted by resetting this bit to zero.
A read of this register simply reflects the status of this bit.
Assert /BSY
Assert /ACK
Lost Arbitration
Arbitration in Progress
Assert /RST
Figure 6. Initiator Command Register
Address: 1
(Write Only)
D7 D6 D5 D4 D3 D2 D1 D0
Assert Data Bus
Assert /ATN
Assert /SEL
Bit 2. Assert /SEL. Writing a one (1) into this bit position
asserts /SEL onto the SCSI Bus. /SEL is normally asserted
after Arbitration has been successfully completed. /SEL
may be disabled by resetting bit 2 to a zero. A read of this
register reflects the status of this bit.
Bit 3. Assert /BSY. Writing a one (1) into this bit position
asserts /BSY onto the SCSI Bus. Conversely, a zero resets
the /BSY signal. Asserting /BSY indicates a successful
selection or reselection. Resetting this bit creates a BusDisconnect condition. Reading this register reflects bit
status.
Bit 4. Assert /ACK. Bit 4 is used by the bus initiator to assert
/ACK on the SCSI Bus. In order to assert /ACK, the Target
Mode bit (Mode Register, bit 6) must be False. Writing a
zero to this bit deasserts /ACK. Reading this register
reflects bit status.
Assert /BSY
Assert /ACK
"0"
Test Mode
Assert /RST
Figure 7. Initiator Command Register
The following describes the operation of all bits in the
Initiator Command Register:
Bit 0. Assert Data Bus. This bit, when set, allows the
contents of the Output Data Register to be enabled as chip
outputs on the signals /DB7-DB0. Parity is also generated
and asserted on /DBP.
When connected as an Initiator, the outputs are only
enabled if the Target Mode bit (Mode Register, bit 6) is 0,
the received signal I//O is False, and the phase signals (C/
/D, I//O, and /MSG) match the contents of the Assert C//D,
Assert I//O, and Assert /MSG in the Target Command
Register.
Bit 5. “0” (Write Bit). Bit 5 should be written with a zero for
proper operation.
Bit 5. LA (Lost Arbitration - Read Bit). Bit 5, when active,
indicates that the SCSI detected a Bus-Free condition,
arbitrated for use of the bus by asserting /BSY and its ID on
the Data Bus, and lost Arbitration due to /SEL being
asserted by another bus device. This bit is active only
when the Arbitrate bit (Mode Register, bit 0) is active.
Bit 6. Test Mode (Write Bit). Bit 6 is written during a test
environment to disable all output drivers, effectively removing the Z5380 from the circuit. Resetting this bit returns
the part to normal operation.
Bit 6. AIP (Arbitration in Process - Read Bit). Bit 6 is used
to determine if Arbitration is in progress. For this bit to be
active, the Arbitrate bit (Mode Register, bit 0) must have
been set previously. It indicates that a Bus-Free condition
has been detected and that the chip has asserted /BSY
and put the contents of the Output Data Register onto the
SCSI Bus. AIP will remain active until the Arbitrate bit is
reset.
Bit 7. Assert /RST. Whenever a one is written to bit 7 of the
Initiator Command Register, the /RST signal is asserted on
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Z5380 SCSI
the SCSI Bus. The /RST signal will remain asserted until this
bit is reset or until an external /RESET occurs. After this bit
is set (1), IRQ goes active and all internal logic and control
registers are reset (except for the interrupt latch and the
Assert /RST bit). Writing a zero to bit 7 of the Initiator
Command Register deasserts the /RST signal. The status
of this bit is monitored by reading the Initiator Command
Register.
Mode Register. Address 2 (Read/Write). The Mode Register controls the operation of the chip. This register determines whether the Z5380 operates as an Initiator or a
Target, whether DMA transfers are being used, whether
parity is checked, and whether interrupts are generated on
various external conditions. This register is read to check
the value of these internal control bits (Figure 8).
Address: 2
Receive Register and set (0) for Start DMA Initiator Receive
Register. The control bit Assert Data Bus (Initiator Command Register, bit 0) must be True (1) for all DMA send
operations. In the DMA mode, /REQ and /ACK are automatically controlled.
The DMA Mode bit is not reset upon the receipt of an /EOP
signal. Any DMA transfer is stopped by writing a zero into
this bit location; however, care must be taken not to cause
/CS and /DACK to be active simultaneously.
Bit 2. Monitor Busy. The Monitor Busy bit, when True (1),
causes an interrupt to be generated for an unexpected
loss of /BSY. When the interrupt is generated due to loss of
/BSY, the lower six bits of the Initiator Command Register
are reset (0) and all signals are removed from the SCSI
Bus.
(Read/Write)
D7 D6 D5 D4 D3 D2 D1 D0
Arbitrate
Bit 3. Enable /EOP interrupt. The enable /EOP interrupt bit,
when set (1), causes an interrupt to occur when the /EOP
(End Of Process) signal is received from the DMA controller logic.
DMA Mode
Monitor /BSY
Enable /EOP Interrupt
Enable Parity Interrupt
Enable Parity Checking
Target Mode
Block Mode DMA
Figure 8. Mode Register
The following describes the operation of all bits in the
Initiator Command Register:
Bit 0. Arbitrate. The Arbitrate bit is set (1) to start the
Arbitration process. Prior to setting this bit, the Output Data
Register should contain the proper SCSI device ID value.
Only one data bit should be active for SCSI Bus Arbitration.
The Z5380 waits for a Bus-Free condition before entering
the Arbitration phase. The results of the Arbitration phase
is determined by reading the status bits LA and AIP
(Initiator Command Register, bits 5 and 6, respectively).
Bit 1. DMA Mode. The DMA Mode bit is normally used to
enable a DMA transfer and must be set (1) prior to writing
Start DMA Send Register, Start DMA Target Register, and
Start DMA Initiator Receiver Register. These three registers are used to start DMA transfers. The Target Mode bit
(Mode Register, bit 6) must be consistent with writes to
Start DMA Target Receive and Start DMA Initiator Receive
Registers; i.e., set (1) for a write to Start DMA Target
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Bit 4. Enable Parity Interrupt. The Enable Parity Interrupt
bit, when set (1), will cause an interrupt (IRQ) to occur if a
parity error is detected. A parity interrupt will only be
generated if the Enable Parity Checking bit (bit 5) is also
enabled (1).
Bit 5. Enable Parity Checking. The Enable Parity Checking
bit determines whether parity errors are ignored or saved
in the parity error latch. If this bit is reset (0), parity is
ignored. Conversely, if this bit is set (1), parity errors are
saved.
Bit 6. Target Mode. The Target Mode bit allows the Z5380
to operate as a SCSI Bus Initiator or Target. With this bit
reset (0), the Z5380 operates as a SCSI Bus Initiator.
Setting Target Mode bit to 1 programs the Z5380 to
operate as a SCSI Bus Target device. If the signals /ATN
and /ACK are to be asserted on the SCSI Bus, the Target
Mode bit must be reset (0). If the signals C//D, I//O, /MSG,
and /REQ are to be asserted on the SCSI Bus, the Target
Mode bit must be set (1).
Bit 7. Block Mode DMA. The Block Mode DMA bit controls
the characteristics of the DMA DRQ-/DACK handshake.
When this bit is reset (0) and the DMA Mode bit is active (1),
the DMA handshake uses the normal interlocked handshake, and the rising edge of /DACK indicates the end of
each byte being transferred. In Block Mode operation,
when the Block Mode DMA bit is set (1) and DMA Mode bit
is active (1), the end of /IOR or /IOW signifies the end of
each byte transferred and /DACK is allowed to remain
active throughout the DMA operation. Ready can then be
used to request the next transfer.
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Z5380 SCSI
FUNCTIONAL DESCRIPTION (Continued)
Target Command Register. Address 3 (Read/Write). When
connected as a target device, the Target Command Register (Figure 9) allows the CPU to control the SCSI Bus
Information Transfer phase and/or to assert /REQ by writing this register. The Target Mode bit (Mode Register, bit
6) must be True (1) for bus assertion to occur. The SCSI
Bus phases are described in Table 2.
Initiator device can use this register to determine the
current bus phase and to poll /REQ for pending data
transfers. This register may also be used to determine why
a particular interrupt occurred. Figure 10 describes the
Current SCSI Bus Status Register.
Address: 4
(Read Only)
D7 D6 D5 D4 D3 D2 D1 D0
Address: 3
(Read/Write)
D7 D6 D5 D4 D3 D2 D1 D0
/DBP
/SEL
Assert I//O
I//O
Assert C//D
C//D
Assert /MSG
/MSG
Assert /REQ
/REQ
"X"
/BSY
/RST
Figure 9. Target Command Register
Figure 10. Current SCSI Bus Status Register
Table 2. SCSI Information Transfer Phases
Bus Phase
Assert
I//O
Assert
C//D
Assert
/MSG
Data Out
Unspecified
Command
Message Out
0
0
0
0
0
0
1
1
0
1
0
1
Data In
Unspecified
Status
Message In
1
1
1
1
0
0
1
1
0
1
0
1
Select Enable Register. Address 4 (Write Only). The
Select Enable Register (Figure 11) is a write-only register
which is used as a mask to monitor a signal ID during a
selection attempt. The simultaneous occurrence of the
correct ID bit, /BSY False, and /SEL True causes an
interrupt. This interrupt can be disabled by resetting all bits
in this register. If the Enable Parity Checking bit (Mode
Register, bit 5) is active (1), parity is checked during
selection.
Address: 4
(Write Only)
D7 D6 D5 D4 D3 D2 D1 D0
When connected as an Initiator with DMA Mode bit True, if
the phase lines (I//O, C//D, and /MSG) do not match the
phase bits in the Target Command Register, a phase
mismatch interrupt is generated when /REQ goes active.
To send data as an Initiator, the Assert I//O, Assert C//D,
and Assert /MSG bits must match the corresponding bits
in the Current SCSI Bus Status Register. The Assert /REQ
bit (bit 3) has no meaning when operating as an Initiator.
/DB0
/DB1
/DB2
/DB3
/DB4
/DB5
/DB6
Bits 4, 5, 6, and 7 are not used.
/DB7
Current SCSI Bus Status Register. Address 4 (Read
Only). The Current SCSI Bus Register is a read-only
register which is used to monitor seven SCSI Bus control
signals, plus the Data Bus parity bit. For example, an
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Figure 11. Select Enable Register
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Z5380 SCSI
Bus and Status Register. Address 5 (Read Only). The
Bus and Status Register (Figure 12) is a read-only register
which can be used to monitor the remaining SCSI control
signals not found in the Current SCSI Bus Status Registers
(/ATN and /ACK), as well as six other status bits. The
following describes each bit of the Bus and Status Register
individually.
Address: 5
(Read Only)
D7 D6 D5 D4 D3 D2 D1 D0
/ACK
/ATN
Busy Error
Phase Match
Interrupt Request Active
Parity Error
Bit 5. Parity Error. Bit 5 is set if a parity error occurs during
a data receive or a device selection. The Parity Error bit can
only be set (1) if the Enable Parity Check bit (Mode
Register, bit 5) is active (1). This bit may be cleared by
reading the Reset Parity/Interrupt Register.
Bit 6. DMA Request. The DMA Request bit allows the CPU
to sample the output pin DRQ. DRQ can be cleared by
asserting /DACK or by resetting the DMA Mode bit (bit 1)
in the Mode Register. The DRQ signal does not reset when
a phase-mismatch interrupt occurs.
Bit 7. End of DMA Transfer. The End of DMA Transfer bit
is set if /EOP, /DACK, and either /IOR or /IOW are simultaneously active for at least 100 ns. Since the /EOP signal
can occur during the last byte sent to the Output Data
Register, the /REQ and /ACK signals should be monitored
to ensure that the last byte has been transferred. This bit is
reset when the DMA Mode bit is reset (0) in the Mode
Register.
DMA Request
End of DMA
Figure 12. Bus and Status Register
Bit 0. /ACK. Bit 0 reflects the condition of the SCSI Bus
control signal /ACK. This signal is normally monitored by
the Target device.
Bit 1. /ATN. Bit 1 reflects the condition of the SCSI Bus
control signal /ATN. This signal is normally monitored by
the Target device.
Input Data Register. Address 6 (Read Only). The input
Data Register (Figure 13) is a read-only register that is
used to read latched data from the SCSI Bus. Data is
latched either during a DMA Target receive operation
when /ACK goes active or during a DMA Initiator receive
when /REQ goes active. The DMA Mode bit (bit 1) must be
set before data can be latched in the Input Data Register.
This register is read under DMA control using /IOR and
/DACK. Parity is optionally checked when the Input Data
Register is loaded.
Address: 6
(Read Only)
D7 D6 D5 D4 D3 D2 D1 D0
Bit 2. Busy Error. The Busy Error bit is active if an unexpected loss of the /BSY signal has occurred. This latch is
set whenever the Monitor Busy bit (Mode Register, bit 2) is
True and /BSY is False. An unexpected loss of /BSY
disables any SCSI outputs and resets the DMA Mode bit
(Mode Register, bit 1).
/DB0
/DB1
/DB2
/DB3
/DB4
Bit 3. Phase Match. The SCSI signals /MSG, C//D, and
I//O, represent the current information Transfer phase. The
Phase Match bit indicates whether the current SCSI Bus
phase matches the lower 3 bits of the Target Command
Register. Phase Match is continuously updated and is only
significant when operating as a Bus Initiator. A phase
match is required for data transfers to occur on the SCSI
Bus.
/DB5
/DB6
/DB7
Figure 13. Input Data Register
Bit 4.Interrupt Request ACTIVE. Bit 4 is set if an enabled
interrupt condition occurs. It reflects the current state of the
IRQ output and can be cleared by reading the Reset Parity/
Interrupt Register.
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Z5380 SCSI
FUNCTIONAL DESCRIPTION (Continued)
DMA Registers
Three write-only registers are used to initiate all DMA
activity. They are: Start DMA Send, Start DMA Target
Receive, and Start DMA Initiator Receive. Performing a
write operation into one of these registers starts the desired type of DMA transfer. Data presented to the Z5380 on
signals D7-D0 during the register write is meaningless and
has no effect on the operation. Prior to writing these
registers, the Block Mode DMA bit (bit 7), the DMA Mode
bit (bit 1), and the Target Mode bit (bit 6) in the Mode
Register must be appropriately set. The individual registers are briefly described as follows:
active. Once arbitration has begun (/BSY asserted), an
arbitration delay of 2.2 µs must elapse before the Data Bus
can be examined to determine if Arbitration is enabled.
This delay is implemented in the controlling software
driver.
The Z5380 is a clockwise device. Delays such as bus-free
delay, bus-set delay, and bus-settle delay are implemented using gate delays. These delays may differ between devices because of inherent process variations, but
are well within the proposed ANSI X3.131 - 1986 specification.
Interrupts
Start DMA Send. Address 5 (Write Only). This register is
written to initiate a DMA send, from the DMA to the SCSI
Bus, for either Initiator or Target role operations. The DMA
Mode bit (Mode Register, bit 1) is set prior to writing this
register.
Start DMA Target Receive. Address 6 (Write Only). This
register is written to initiate a DMA receive - from the SCSI
Bus to the DMA, for Target operation only. The DMA Mode
bit (bit 1) and the Target Mode bit (bit 6) in the Mode
Register must both be set (1) prior to writing this register.
Start DMA Initiator Receive. Address 7 (Write Only). This
register is written to initiate a DMA receive - from the SCSI
Bus to the DMA, for Initiator operation only. The DMA Mode
bit (bit 6) must be False (0) in the Mode Register prior to
writing this register.
Reset Parity/Interrupt. Address 7 (Read Only). Reading
this register resets the Parity Error bit (bit 5), the Interrupt
Request bit (bit 4), and the Busy Error bit (bit 2) in the Bus
and Status Register.
On-Chip SCSI Hardware Support
The Z5380 is easy to use because of its simple architecture. The chip allows direct control and monitoring of the
SCSI Bus by providing a latch for each signal. However,
portions of the protocol define timings which are much too
quick for traditional microprocessors to control. Therefore,
hardware support has been provided for DMA transfers,
bus arbitration, phase change monitoring, bus disconnection, bus reset, parity generation, parity checking, and
device selection/reselection.
Arbitration is accomplished using a bus-free filter to continuously monitor /BSY. If /BSY remains inactive for at least
1.2 µs, the SCSI Bus is considered free and Arbitration may
begin. Arbitration will begin if the bus is free, /SEL is
inactive, and the Arbitrate bit (Mode Register, bit 0) is
10
The Z5380 provides an interrupt output (IRQ) to indicate a
task completion or an abnormal bus occurrence. The use
of interrupts is optional and may be disabled by resetting
the appropriate bits in the Mode Register or the Select
Enable Register.
When an interrupt occurs, the Bus and Status Register and
the Current SCSI Bus Status Register (Figures 12 and 10)
must be read to determine which condition created the
interrupt. IRQ can be reset simply by reading the Reset
Parity/Interrupt Register or by an external chip reset
/RESET active for 200 ns.
Assuming the Z5380 has been properly initialized, an
interrupt is generated if the chip is selected or reselected;
if an /EOP signal occurs during a DMA transfer; if a SCSI
Bus reset occurs; if a parity error occurs during a data
transfer; if a bus phase mismatch occurs; or if a SCSI Bus
disconnection occurs.
Selection/Reselection Interrupt
The Z5380 generates a select interrupt if /SEL is active (0),
its device ID is True and /BSY is False for at least a bussettle delay. If I//O is active, this is considered a reselect
interrupt. The correct ID bit is determined by a match in the
Select Enable Register. Only a single bit match is required
to generate an interrupt. This interrupt may be disabled by
writing zeros into all bits of the Select Enable Register.
If parity is supported, parity should be good during the
selection phase. Therefore, if the Enable Parity bit (Mode
Register, bit 5) is active, the Parity Error bit is checked to
ensure that a proper selection has occurred. The Enable
Parity Interrupt bit need not be set for this interrupt to be
generated.
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
The proposed SCSI specification also requires that no
more than two device ID’s be active during the selection
process. To ensure this, the Current SCSI Data Register is
read.
The proper values for the Bus and Status Register and the
Current SCSI Bus Status Register are displayed in Figures
14 and 15, respectively.
The proper values for the Bus and Status Register and the
Current SCSI Bus Status Register for this interrupt are
shown in Figures 16 and 17.
D7
1
D0
0
0
1
0
0
0
X
/ACK
D0
D7
0
0
0
1
X
0
X
/ATN
0
Busy Error
Phase Match
/ACK
Interrupt Request Active
/ATN
Parity Error
Busy Error
DMA Request
Phase Match
End of DMA
Interrupt Request Active
Parity Error
DMA Request
Figure 16. Bus and Status Register
End of DMA
Figure 14. Bus and Status Register
D7
0
D7
0
D0
1
1
X
D0
0
0
X
X
X
0
X
X
0
X
/DBP
X
/SEL
I//O
/DBP
C//D
/SEL
/MSG
I//O
/REQ
C//D
/BSY
/MSG
/RST
/REQ
/BSY
Figure 17. Current SCSI Bus Status Register
/RST
Figure 15. Current SCSI Bus Status Register
End Of Process (EOP) Interrupt
An End Of Process signal (EOP) which occurs during a
DMA transfer (DMA Mode True) will set the End of DMA
Status bit (bit 7) and will optionally generate an interrupt if
Enable EOP Interrupt bit (Mode Register, bit 3) is True. The
/EOP pulse will not be recognized (End of DMA bit set)
unless /EOP, /DACK, and either /IOR or /IOW are concurrently active for at least 100 ns. DMA transfers can still
occur if /EOP was not asserted at the correct time. This
interrupt is disabled by resetting the Enable EOP Interrupt
bit.
PS97SCC0100
The End of DMA bit is used to determine when a block
transfer is complete. Receive operations are complete
when there is no data left in the chip and no additional
handshakes occurring. The only exception to this is receiving data as an Initiator and the Target opts to send
additional data for the same phase. In this /REQ goes
active and the new data is present in the Input Data
Register. Since a phase-mismatch interrupt will not occur,
/REQ and /ACK need to be sampled to determine that the
Target is attempting to send more data.
PS009101-0201
11
ZILOG
Z5380 SCSI
FUNCTIONAL DESCRIPTION (Continued)
D7
For send operations, the End of DMA bit is set when the
DMA finishes its transfers, but the SCSI transfer may still be
in progress. If connected as a Target, /REQ and /ACK
should be sampled until both are False. If connected as an
Initiator, a phase change interrupt is used to signal the
completion of the previous phase. It is possible for the
Target to request additional data for the same phase. In
this case, a phase change will not occur and both /REQ
and /ACK are sampled to determine when the last byte was
transferred.
SCSI Bus Reset Interrupt
The Z5380 generates an interrupt when the /RST signal
transitions to True. The device releases all bus signals
within a bus-clear delay of this transition. This interrupt also
occurs after setting the Assert /RST bit (Initiator Command
Register, bit 7). This interrupt cannot be disabled. (Note:
/RST is not latched in bit 7 of the Current SCSI Bus Status
Register and is not active when this port is read. For this
case, the Bus Reset interrupt is determined by default.)
The proper values for the Bus and Status Register and the
Current SCSI Bus Status Register are displayed in Figures
18 and 19, respectively.
D7
0
D0
X
0
1
X
0
X
X
X
D0
X
X
X
X
X
X
X
/DBP
/SEL
I//O
C//D
/MSG
/REQ
/BSY
/RST
Figure 19. Current SCSI Bus Status Register
Parity Error Interrupt
An Interrupt is generated for a received parity error if the
Enable Parity Check (bit 5) and the Enable Parity Interrupt
(bit 4) bits are set (1) in the Mode Register. Parity is
checked during a read of the Current SCSI Data Register
and during a DMA receive operation. A parity error can be
detected without generating an interrupt by disabling the
Enable Parity Interrupt bit and checking the Parity Error
flag (Bus and Status Register, bit 5).
The proper values for the Bus and Status Register and the
Current SCSI Bus Status Register are displayed in Figures
20 and 21, respectively.
/ACK
/ATN
Busy Error
D7
Phase Match
0
D0
X
1
1
1
0
X
X
Interrupt Request Active
Parity Error
/ACK
DMA Request
/ATN
End of DMA
Busy Error
Phase Match
Figure 18. Bus and Status Register
Interrupt Request Active
Parity Error
DMA Request
End of DMA
Figure 20. Bus and Status Register
12
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
D7
0
D7
D0
1
1
X
X
X
0
0
X
D0
0
0
1
0
0
X
0
/DBP
/ACK
/SEL
/ATN
I//O
Busy Error
C//D
Phase Match
/MSG
Interrupt Request Active
/REQ
Parity Error
/BSY
DMA Request
/RST
End of DMA
Figure 21. Current SCSI Bus Status Register
Bus Phase Mismatch Interrupt
The SCSI phase lines are comprised of the signals I//O,
C//D, and /MSG. These signals are compared with the
corresponding bits in the Target Command Register: Assert I//O (bit 0), Assert C//D (bit 1), and Assert /MSG (bit 2).
The comparison occurs continually and is reflected in the
Phase Match bit (bit 3) of the Bus and Status Register. If the
DMA Mode bit (Mode Register, bit 1) is active and a phase
mismatch occurs when /REQ transitions from False to
True, an interrupt (IRQ) is generated.
Figure 22. Bus and Status Register
D7
0
D0
1
X
X
X
X
0
X
/DBP
/SEL
I//O
C//D
/MSG
/REQ
A phase mismatch prevents the recognition of /REQ and
removes the chip from the bus during an Initiator send
operation (/DB7-/DB0 and /DBP will not be driven even
through the Assert Data Bus bit (Initiator Command Register, bit 0) is active). This may be disabled by resetting the
DMA Mode bit (Note: It is possible for this interrupt to occur
when connected as a Target if another device is driving the
phase lines to a different state).
The proper values for the Bus and Status Register and the
Current SCSI Bus Status Register are displayed in Figures
22 and 23, respectively.
PS97SCC0100
/BSY
/RST
Figure 23. Current SCSI Bus Status Register
Loss of BSY Interrupt
If the Monitor Busy bit (bit 2) in the Mode Register is active,
an interrupt is generated if the BSY signal goes False for at
least a bus-settle delay. This interrupt is disabled by
resetting the Monitor Busy bit. Register values are displayed in Figures 24 and 25.
PS009101-0201
13
ZILOG
Z5380 SCSI
FUNCTIONAL DESCRIPTION (Continued)
D7
0
reading the Current SCSI Bus Status Register; however,
this signal is not latched and may not be present when this
port is read).
D0
0
0
1
X
1
0
0
/ACK
/ATN
Busy Error
Phase Match
Interrupt Request Active
Parity Error
DMA Request
SCSI Bus Reset (/RST) Issued
If the CPU sets the Assert /RST bit (bit 7) in the Initiator
Command Register, the /RST signal goes active on the
SCSI Bus and an internal reset is performed. Again, all
internal logic and registers are cleared except for the IRQ
interrupt latch and the Assert /RST bit (bit 7) in the Initiator
Command Register. The /RST signal will continue to be
active until the Assert /RST bit is reset or until a hardware
reset occurs.
End of DMA
Figure 24. Bus and Status Register
D7
0
1.
2.
3.
4.
D0
0
0
X
X
X
0
Data Transfers
Data is transferred between SCSI Bus devices in one of
four modes (Reference Figures 26-41):
0
Programmed I/O
Normal DMA
Block Mode DMA
Pseudo DMA
/DBP
The following sections describe these modes in detail
(Note: For all data transfer operations, /DACK and /CS
should never be active simultaneously).
/SEL
I//O
C//D
/MSG
/REQ
/BSY
/RST
Figure 25. Current SCSI Bus Status Register
Reset Conditions
Three possible reset situations exist with the Z5380, as
follows:
Hardware Chip Reset
When the signal /RST is active for at least 200 ns, the Z5380
device is re-initialized and all internal logic and control
registers are cleared. This is a chip reset only and does not
create a SCSI Bus-Reset condition.
SCSI Bus Reset (/RST) Received
When a SCSI /RST signal is received, an IRQ interrupt is
generated and a chip reset is performed. All internal logic
and registers are cleared, except for the IRQ interrupt latch
and the Assert /RST bit (bit 7) in the Initiator Command
Register. (Note: The /RST signal may be sampled by
14
Programmed I/O Transfers
Programmed I/O is the most primitive form of data transfer.
The /REQ and /ACK handshake signals are individually
monitored and asserted by reading and writing the appropriate register bits. This type of transfer is normally used
when transferring small blocks of data such as command
blocks or message and status bytes. An Initiator send
operation would begin by setting the C//D, I//O, and /MSG
bits in the Target Command Register to the correct state so
that a phase match exists. In addition to the phase match
condition, it is necessary for the Assert Data Bus bit
(Initiator Command Register, bit 0) to be True and the
received I/O signal to be False for the Z5380 to send data.
For each transfer, the data is loaded into the Output Data
Register. The CPU then waits for the /REQ bit (Current SCSI
Bus Status Register, bit 5) to become active. Once /REQ
goes active, the Phase Match bit (Bus and Status Register,
bit 3) is checked and the Assert /ACK bit (Initiator Command Register, bit 4) is set. The /REQ bit is sampled until
it becomes False and the CPU resets the Assert /ACK bit
to complete the transfer.
Normal DMA Mode
DMA transfers are normally used for large block transfers.
The SCSI chip outputs a DMA request (DRQ) whenever it
is ready for a byte transfer. External DMA logic uses this
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
DRQ signal to generate /DACK and an /IOR or an /IOW
pulse to the Z5380. DRQ goes inactive when /DACK is
asserted and /DACK goes inactive some time after the
minimum read or write pulse width. This process is repeated for every byte. For this mode, /DACK should not be
allowed to cycle unless a transfer is taking place.
Block Mode DMA
Some popular DMA Controllers, such as the 9517A, provide a Block Mode DMA transfer. This type of transfer
allows the DMA controller to transfer blocks of data without
relinquishing the use of the Data Bus to the CPU after each
byte is transferred; thus, faster transfer rates are achieved
by eliminating the repetitive access and release of the CPU
Bus. If the Block Mode DMA bit (Mode Register, bit 7) is
active, the Z5380 begins the transfer by asserting DRQ.
The DMA controller then asserts /DACK for the remainder
of the block transfer. DRQ goes inactive for the duration of
the transfer. The Ready output is used to control the
transfer rate. Non-Block Mode DMA transfers end when
/DACK goes False, whereas Block Mode DMA transfers
end when /IOR or /IOW becomes inactive. Since this is the
case, DMA transfers may be started sooner in a Block
Mode transfer. To obtain optimum performance in Block
Mode operation, the DMA logic optionally uses the normal
DMA mode interlocking handshake. Ready is still available
to throttle the DMA transfer, but DRQ is 30 to 40 ns faster
than Ready and is used to start the cycle sooner. The
methods described under “Halting a DMA Operation”
apply for all DMA operations.
Pseudo DMA Mode
To avoid the tedium of monitoring and asserting the request/acknowledgment handshake signals for programmed I/O transfers, the system can be designed to
implement a pseudo DMA mode. This mode is implemented by programming the Z5380 to operate in the DMA
mode, but using the CPU to emulate the DMA handshake.
DRQ may be detected by polling the DMA Request bit (bit
6) in the Bus and Status Register, by sampling the signal
through an external port, or by using it to generate a CPU
interrupt. Once DRQ is detected, the CPU can perform a
read or write data transfer. This CPU read/write is externally decoded to generate the appropriate /DACK and
/IOR or /IOW signals.
Halting a DMA Operation
The /EOP signal is not the only way to halt a DMA transfer.
A bus phase mismatch or a reset of the DMA Mode bit
(Mode Register, bit 1) can also terminate a DMA cycle for
the current bus phase.
Using the /EOP Signal
If /EOP is used, it should be asserted for at least 100 ns
while /DACK and /IOR or /IOW are simultaneously active.
Note, however, that if /IOR or /IOW is not active, an interrupt
is generated, but the DMA activity continues. The /EOP
signal does not reset the DMA Mode bit. Since the /EOP
signal can occur during the last byte sent to the Output
Data Register, the /REQ and /ACK signals are monitored to
ensure that the last byte has transferred.
Bus Phase Mismatch Interrupt
A bus phase mismatch interrupt is used to halt the transfer
if operating as an Initiator. Using this method frees the host
from maintaining a data length counter and frees the DMA
logic from providing the /EOP signal. If performing an
Initiator send operation, the Z5380 requires /DACK to
cycle before /ACK goes inactive. Since phase changes
cannot occur if /ACK is active, either /DACK must be
cycled after the last byte is sent or the DMA Mode bit must
be reset in order to receive the phase mismatch interrupt.
Resetting the DMA Mode Bit
A DMA operation may be halted at any time simply by
resetting the DMA Mode bit. It is recommended that the
DMA Mode bit be reset after receiving an /EOP or bus
phase-mismatch interrupt. The DMA Mode bit must then
be set before writing any of the start DMA registers for
subsequent bus phases.
If resetting the DMA Mode bit is used instead of /EOP for
Target role operation, then care must be taken to reset this
bit at the proper time. If receiving data as a Target device,
the DMA Mode bit must be reset once the last DRQ is
received and before /DACK is asserted to prevent an
additional /REQ from occurring. Resetting this bit causes
DRQ to go inactive. However, the last byte received
remains in the Input Data Register and may be obtained
either by performing a normal CPU read or by cycling
/DACK and /IOR. In most cases, /EOP is easier to use when
operating as a Target device.
Often, external decoding logic is necessary to generate
the Z5380 /CS signal. This same logic may be used to
generate /DACK at no extra cost and provide an increased
performance in programmed I/O transfers.
PS97SCC0100
PS009101-0201
15
ZILOG
Z5380 SCSI
READ REGISTERS
Address: 0
(Read Only)
Address: 3
D7 D6 D5 D4 D3 D2 D1 D0
(Read Only)
D7 D6 D5 D4 D3 D2 D1 D0
/DB0
Assert I//O
/DB1
Assert C//D
/DB2
Assert /MSG
/DB3
Assert /REQ
/DB4
"0"
/DB5
/DB6
Figure 29. Target Command Register
/DB7
Address: 4
Figure 26. Current SCSI Data Register
Address: 1
(Read Only)
D7 D6 D5 D4 D3 D2 D1 D0
/DBP
(Read Only)
/SEL
D7 D6 D5 D4 D3 D2 D1 D0
I//O
Assert Data Bus
C//D
Assert /ATN
/MSG
Assert /SEL
/REQ
Assert /BSY
/BSY
Assert /ACK
/RST
Lost Arbitration
Arbitration in Progress
Figure 30. Current SCSI Bus Status Register
Assert /RST
(Read Only)
Address: 5
Figure 27. Initiator Command Register
Address: 2
D7 D6 D5 D4 D3 D2 D1 D0
(Read Only)
/ACK
D7 D6 D5 D4 D3 D2 D1 D0
/ATN
Busy Error
Arbitrate
Phase Match
DMA Mode
Interrupt Request Active
Monitor /BSY
Parity Error
Enable /EOP Interrupt
DMA Request
Enable Parity Interrupt
End of DMA
Enable Parity Checking
Target Mode
Figure 31. Bus and Status Register
Block Mode DMA
Figure 28. Mode Register
16
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
Address: 6
(Read Only)
Address: 7
(Read Only)
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
"X"
/DB0
X = Don't Care
/DB1
/DB2
/DB3
Figure 33. Reset Parity/Interrupt
/DB4
/DB5
/DB6
/DB7
Figure 32. Input Data Register
WRITE REGISTERS
Address: 0
Address: 2
(Write Only)
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
/DB0
Arbitrate
/DB1
DMA Mode
/DB2
Monitor /BSY
/DB3
Enable /EOP Interrupt
/DB4
Enable Parity Interrupt
/DB5
Enable Parity Checking
/DB6
Target Mode
/DB7
Block Mode DMA
Figure 34. Output Data Register
Address: 1
(Write Only)
Figure 36. Mode Register
(Write Only)
Address: 3
D7 D6 D5 D4 D3 D2 D1 D0
(Write Only)
D7 D6 D5 D4 D3 D2 D1 D0
Assert Data Bus
Assert I//O
Assert /ATN
Assert C//D
Assert /SEL
Assert /MSG
Assert /BSY
Assert /REQ
Assert /ACK
"X"
"0"
Figure 37. Target Command Register
Test Mode
Assert /RST
Figure 35. Initiator Command Register
PS97SCC0100
PS009101-0201
17
ZILOG
Z5380 SCSI
WRITE REGISTERS (Continued)
Address: 4
(Write Only)
Address: 6
D7 D6 D5 D4 D3 D2 D1 D0
(Write Only)
D7 D6 D5 D4 D3 D2 D1 D0
/DB0
"X"
/DB1
/DB2
Figure 40. Start DMA Target Receive
/DB3
/DB4
/DB5
Address: 7
(Write Only)
/DB6
D7 D6 D5 D4 D3 D2 D1 D0
/DB7
"X"
Figure 38. Select Enable Register
Figure 41. Start DMA Initiator Receive
Address: 5
(Write Only)
D7 D6 D5 D4 D3 D2 D1 D0
"X"
Figure 39. Start DMA Send
ABSOLUTE MAXIMUM RATINGS
Voltages on all pins
with respect to GND ................................. –0.3V to +7.0V
Operating Ambient Temperature ................................... †
Storage Temperature ............................ –65°C to +150°C
Note:
† See Ordering Information
18
Stresses greater than those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; operation of the device at
any condition above those indicated in the operational
sections of these specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods
may affect device reliability.
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
STANDARD TEST CONDITIONS
VL
The DC Characteristics section below apply for the following standard test conditions, unless otherwise noted. All
voltages are referenced to GND. Positive current flows into
the referenced pin. Standard conditions are as follows
(Figures 42 and 43):
■
■
■
2K
From Output
Under Test
+4.5V < VCC < +5.5V
GND = 0V
TA as specified in Ordering Information
120 pf
2.0
2.4
9K
2.0
Test
Points
0.4
0.8
0.8
Figure 42. Switching Test Circuit
Figure 43. Standard Test Load
DC CHARACTERISTICS
Z5380
Symbol
Parameter
VDD
VIH
VIL
Supply Voltage
High-Level Input Voltage
Low-Level Input Voltage
IIH1
High-Level Input Current
SCSI Bus Pins
High-Level Input Current
All Other Pins
VIH = 5.25V
VIL = 0V
VIH = 5.25V
VIL = 0V
Low-Level Input Current
SCSI Bus Pins
Low-Level Input Current
All Other Pins
VIH = 5.25V
VIL = 0V
VIH = 5.25V
VIL = 0V
VOH
High-Level Output Voltage
VOL1
Low-Level Output Voltage
SCSI Bus Pins
VOL2
Low-Level Output Voltage
All Other Pins
Supply Current
Operating Free-Air
IIH2
IIL1
IIL2
IDD
TA
PS97SCC0100
Conditions
Min
Max
Units
4.75
2.0
–0.3
5.25
5.25
0.8
V
V
V
50
µA
10
µA
–50
µA
–10
µA
IOH = –3 mA
VDD = 4.75V
IOL = 48 mA
VDD = 4.75V
2.4
V
0.5
V
IOL = 7 mA
VDD = 4.75V
15 mA
0.5
V
0
PS009101-0201
70
C
19
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
CPU Write Cycle Timing Diagram
A2-A0
1
2
/CS
3
4
/IOW
5
6
D7-D0
Figure 44. CPU Write Cycle
AC CHARACTERISTICS
CPU Write Cycle Timing Table
No
Description
Min
Max
Units
1
2
3
Address Setup to Write Enable [1]
Address Hold from End Write Enable [1]
Write Enable Width [1]
20
20
70
ns
ns
ns
4
5
6
Chip Select Hold from End of /IOW
Data Setup to end of Write Enable [1]
Data Hold Time form End of /IOW
0
50
30
ns
ns
ns
Note:
[1] Write Enable is the occurrence of /IOW and /CS.
20
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
CPU Read Cycle Timing Diagram
A2-A0
1
2
/CS
3
/IOR
4
5
D7-D0
Figure 45. CPU Read Cycle
AC CHARACTERISTICS
CPU Read Cycle Timing Table
No
Description
Min
Max
Units
1
2
Address Setup to Read Enable [1]
Address Hold from End Read Enable [1]
20
20
ns
ns
3
4
5
Chip Select Hold from End of /IOR
Data Access Time from Read Enable [1]
Data Hold Time from End of Read Enable [1]
0
130
20
ns
ns
ns
Note:
[1] Read Enable is the occurrence of /IOR and /CS.
PS97SCC0100
PS009101-0201
21
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Write (Non-Block Mode) Target Send Cycle Timing Diagram
DRQ
1
2
/DACK
3
4
5
6
/IOW
D7-D0
7
/EOP
8
9
/REQ
11
10
/ACK
12
13
/DB7-/DB0,
/DBP
Figure 46. DMA Write (Non-Block Mode) Target Send Cycle
22
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Write (Non-Block Mode) Target Send Cycle Table
No
Description
Min
Max
1
2
3
4
DRQ Low from /DACK Low
/DACK High to DRQ High
Write Enable Width [1]
/DACK Hold from /IOW High
130
30
100
0
ns
ns
ns
ns
5
6
7
8
Data Setup to End of Write Enable [1]
Data Hold Time from End of /IOW
Width of /EOP Pulse [2]
/ACK Low to /REQ High
50
40
100
25
ns
ns
ns
ns
9
10
11
12
13
/REQ from End of /DACK (/ACK High)
/ACK Low to DRQ High (Target)
/ACK High to /REQ Low (/DACK High)
Data Hold from Write Enable
Data Setup to /REQ Low (Target)
30
15
20
15
60
125
150
110
150
Units
ns
ns
ns
ns
ns
Notes:
[1] Write Enable is the occurrence of /IOW and /DACK.
[2] /EOP, /IOW, and /DACK must be concurrently Low for at least T7 for proper recognition of the /EOP pulse.
PS97SCC0100
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23
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Write (Non-Block Mode) Initiator Send Cycle Timing Diagram
DRQ
1
2
/DACK
3
4
/IOW
5
6
D7-D0
7
/EOP
/REQ
8
9
10
/ACK
12
11
/DB7-/DB0,
/DBP
Figure 47. DMA Write (Non-Block Mode) Initiator Send Cycle
24
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Write (Non-Block Mode) Initiator Send Cycle Table
No
Description
Min
Max
1
2
3
4
DRQ Low from /DACK Low
/DACK High to DRQ High
Write Enable Width [1]
/DACK Hold from End of /IOW
130
30
100
0
ns
ns
ns
ns
5
6
7
8
Data Setup to End of Write Enable [1]
Data Hold Time from End of /IOW
Width of /EOP Pulse [2]
/REQ Low to /ACK Low
50
40
100
20
ns
ns
ns
ns
9
10
11
12
/REQ High to DRQ High
/DACK High to /ACK High
/IOW High to Valid SCSI Data
Data Hold from Write Enable [1]
20
25
100
15
160
110
150
Units
ns
ns
ns
ns
Notes:
[1] Write Enable is the occurrence of /IOW and /DACK.
[2] /EOP, /IOW, and /DACK must be concurrently Low for at least T7 for proper recognition of the /EOP pulse.
PS97SCC0100
PS009101-0201
25
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Read (Non-Block Mode) Target Receive Cycle Timing Diagram
DRQ
1
2
/DACK
3
/IOR
4
5
D7-D0
6
/EOP
7
8
/REQ
9
10
/ACK
11
12
/DB7-/DB0,
/DBP
Figure 48. DMA Read (Non-Block Mode) Target Receive Cycle
26
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Read (Non-Block Mode) Target Receive Cycle Table
No
Description
Min
Max
1
2
3
4
DRQ Low from /DACK Low
/DACK High to DRQ High
/DACK Hold Time from End of /IOR
Data Access Time from Read Enable [1]
130
30
0
115
ns
ns
ns
ns
5
6
7
8
Data Hold Time from End of /IOR
Width of /EOP Pulse [2]
/ACK Low to DRQ High
/DACK High to /REQ Low (/ACK High)
20
100
15
30
ns
ns
ns
ns
9
10
11
12
/ACK Low to /REQ High
/ACK High to /REQ Low (/DACK High)
Data Setup Time to /ACK
Data Hold Time from /ACK
25
20
20
50
110
150
125
150
Units
ns
ns
ns
ns
Notes:
[1] Read Enable is the occurrence of /IOR and /DACK.
[2] /EOP, /IOR, and /DACK must be concurrently Low for at least T6 for proper recognition of the /EOP pulse.
PS97SCC0100
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27
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Read (Non-Block Mode) Initiator Receive Cycle Timing Diagram
DRQ
1
2
/DACK
3
/IOR
4
5
D7-D0
6
/EOP
7
8
/REQ
9
10
/ACK
11
12
/DB7-/DB0,
/DBP
Figure 49. DMA Read (Non-Block Mode) Initiator Receive Cycle
28
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Read (Non-Block Mode) Initiator Receive Cycle Table
No
Description
Min
Max
1
2
3
4
DRQ Low from /DACK Low
/DACK High to DRQ High
/DACK Hold Time from End of /IOR
Data Access Time from Read Enable [1]
130
30
0
115
ns
ns
ns
ns
5
6
7
8
Data Hold Time from End of /IOR
Width of /EOP Pulse [2]
/REQ Low to DRQ High
/DACK High to /ACK High (/REQ High)
20
100
20
25
ns
ns
ns
ns
9
10
11
12
/REQ Low to /ACK Low
/REQ High to /ACK High (/DACK High)
Data Setup Time to /REQ
Data Hold Time from /REQ
20
15
20
50
160
160
140
Units
ns
ns
ns
ns
Notes:
[1] Read Enable is the occurrence of /IOR and /DACK.
[2] /EOP, /IOR, and /DACK must be concurrently Low for at least T6 for proper recognition of the /EOP pulse.
PS97SCC0100
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29
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Write (Block Mode) Target Send Cycle Timing Diagram
DRQ
1
/DACK
2
3
/IOW
4
5
D7-D0
6
/EOP
7
8
/REQ
9
/ACK
10
11
12
READY
13
14
/DB7-/DB0,
/DBP
Figure 50. DMA Write (Block Mode) Target Send Cycle
30
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PS97SCC0100
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Write (Block Mode) Target Send Cycle Table
No
Description
Min
Max
1
2
3
4
DRQ Low from /DACK Low
Write Enable Width [1]
Write Recovery Time
Data Setup to End of Write Enable [1]
130
100
120
50
ns
ns
ns
ns
5
6
7
8
Data Hold Time from End of /IOW
Width of /EOP Pulse [2]
/ACK Low to /REQ High
/REQ from End of /IOW (/ACK High)
40
100
25
40
ns
ns
ns
ns
9
10
11
12
/REQ from End of /ACK (/IOW High)
/ACK Low to READY High
READY High to /IOW High
/IOW High to READY Low
20
20
70
20
13
14
Data Hold from /ACK Low
Data Setup to /REQ Low
40
60
125
180
170
140
140
Units
ns
ns
ns
ns
ns
ns
Notes:
[1] Write Enable is the occurrence of /IOW and /DACK.
[2] /EOP, /IOW, and /DACK must be concurrently Low for at least T6 for proper recognition of the /EOP pulse.
PS97SCC0100
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31
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Read (Block Mode) Target Receive Cycle Timing Diagram
DRQ
1
/DACK
2
/IOR
3
4
D7-D0
5
/EOP
6
/REQ
7
8
/ACK
9
10
11
READY
12
13
/DB7-/DB0,
/DBP
Figure 51. DMA Read (Block Mode) Target Receive Cycle
32
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
AC CHARACTERISTICS
DMA Read (Block Mode) Target Receive Cycle Table
No
Description
Min
1
2
3
4
DRQ Low from /DACK Low
/IOR Recovery Time
Data Access Time from Read Enable [1]
Data Hold Time from End of /IOR
130
120
110
20
5
6
7
8
Width of /EOP Pulse [2]
/IOR High to /REQ Low
/ACK Low to /REQ High
/ACK High to /REQ Low (/IOR High)
100
30
25
20
9
10
11
12
13
/ACK Low to READY High
READY High to Valid Data
/IOR High to READY Low
Data Setup Time to /ACK
Data Hold Time from /ACK
20
50
20
20
50
Max
Units
ns
ns
ns
ns
190
125
170
140
140
ns
ns
ns
ns
ns
ns
ns
ns
ns
Notes:
[1] Read Enable is the occurrence of /IOR and /DACK.
[2] /EOP, /IOR, and /DACK must be concurrently Low for at least T5 for proper recognition of the /EOP pulse.
PS97SCC0100
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ZILOG
Z5380 SCSI
AC CHARACTERISTICS
Arbitration
/RST
/SEL
1
/BSY
2
/DB7-DB0,
/DBP
ARBITRATE
Figure 52. Arbitration
No
Description
Min
Max
Units
1
2
Bus Clear from /SEL Low
Arbitrate Start from /BSY High
1200
600
2200
ns
ns
Max
Units
AC CHARACTERISTICS
Reset
1
/RESET
Figure 53. Reset
No
Description
Min
1
Minimum Width of /RESET
200
34
PS009101-0201
ns
PS97SCC0100
ZILOG
Z5380 SCSI
Z5380 NOTES
1. Edge-triggered /RST Interrupt. If the SCSI Bus is not
terminated, the /RST interrupt is continually generated.
2. True End of DMA Interrupt. The Z5380 generates an
interrupt when it receives the last byte from the DMA,
not when the last byte is transferred to the SCSI Bus.
3. Return to Ready after /EOP Interrupt. When operating in Block Mode DMA, the Z5380 does not return the
Ready signal to a Ready condition. This locks up the
bus and prevents the CPU from executing.
4. SCSI handshake after /EOP occurs. If an EOP occurs when receiving data, a subsequent request will
cause /ACK to be asserted even though no DRQ is
issued.
5. Reselection Interrupt. During reselection, if the Target Command Register does not reflect the current
bus phase (most likely Data Out), the reselection
interrupt may get reset.
PS97SCC0100
6. Phase Mismatch Interrupt. A phase mismatch interrupt is not guaranteed after a reselection for the
following reasons:
– DMA Mode bit must be set in order to receive
a phase mismatch interrupt.
– DMA Mode bit can not be set unless /BSY is
active.
– /BSY can not be asserted until after the
reselection has occurred.
– Once /BSY is asserted, the Target may assert
/REQ in less than 500 ns.
– The phase mismatch interrupt is generated on
the active edge of /REQ. If the DMA Mode bit
is not set before the /REQ goes active, the
phase mismatch interrupt will not occur.
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ZILOG
Z5380 SCSI
PACKAGE INFORMATION
40-Pin DIP Package Diagram
44-Pin PLCC Package Diagram
36
PS009101-0201
PS97SCC0100
ZILOG
Z5380 SCSI
ORDERING INFORMATION
Z5380 SCSI
40-Pin DIP
Z0538001PSC
44-Pin PLCC
Z0538001VSC
Package
P = Plastic DIP
V = Plastic Leadless Chip Carrier
Temperature
S = 0°C to +70°C
E = –40°C to +85°C
Speed
1.5 MB/s
Environmental
C = Plastic Standard
Example:
Z 5380 01 V S
C
is a Z5380, 1.5 MB/s, PLCC, 0°C to +70°C, Plastic Standard Flow
Environmental Flow
Temperature
Package
Speed
Product Number
Zilog Prefix
© 1997 by Zilog, Inc. All rights reserved. No part of this document
may be copied or reproduced in any form or by any means
without the prior written consent of Zilog, Inc. The information in
this document is subject to change without notice. Devices sold
by Zilog, Inc. are covered by warranty and patent indemnification
provisions appearing in Zilog, Inc. Terms and Conditions of Sale
only. Zilog, Inc. makes no warranty, express, statutory, implied or
by description, regarding the information set forth herein or
regarding the freedom of the described devices from intellectual
property infringement. Zilog, Inc. makes no warranty of merchantability or fitness for any purpose. Zilog, Inc. shall not be
responsible for any errors that may appear in this document.
Zilog, Inc. makes no commitment to update or keep current the
information contained in this document.
PS97SCC0100
Zilog’s products are not authorized for use as critical components in life support devices or systems unless a specific written
agreement pertaining to such intended use is executed between
the customer and Zilog prior to use. Life support devices or
systems are those which are intended for surgical implantation
into the body, or which sustains life whose failure to perform,
when properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result in
significant injury to the user.
Zilog, Inc. 210 East Hacienda Ave.
Campbell, CA 95008-6600
Telephone (408) 370-8000
Telex 910-338-7621
FAX 408 370-8056
Internet: http://www.zilog.com
PS009101-0201
37