LAN91C95
ISA/PCMCIA Full Duplex Single-Chip
Ethernet and Modem Controller with RAM
FEATURES
•
•
•
•
•
•
•
•
•
•
•
•
•
ISA/PCMCIA Single Chip Ethernet Controller
With Modem Support
6 Kbytes Built-In RAM
Supports IEEE 802.3 (ANSI 8802-3) Ethernet
Standards
Full Duplex Support
Hardware Memory Management Unit
Built-In AUI and 10BASE-T Network Interfaces
SimultaskingJ - Early Transmit and Early
Receive Functions
Advanced Power Management
Features/Including Magic Packet Frame
Control
Software Compatible with LAN91C92/
LAN91C94 (in ISA Mode)
Configuration Registers Implement Cardbus
Multi-Function Specification V3.0 with
Backward Compatibility to V2.1
Interfaces Directly to Lucent Technologies and
Conexant (formerly Rockwell) Modem
Chipsets
On-Chip Attribute Memory (CIS) of up to 512
Bytes (On Even Addresses) For Card
Configuration Information; Expandable
Externally
Option for Serial or Parallel EEPROM for CIS
•
•
•
•
•
Optional External Flash Capability for XIP
(Execute in Place)
Automatic Technology to Detect 10 BASE-T
TX/RX Polarity Reversal
Low Power CMOS Design
Supports Magic Packet Wakeup
128 Pin TQFP Package
Bus Interface
•
•
•
•
•
•
•
•
•
•
•
•
Direct Interface to ISA and PCMCIA with No
Wait States
High Impedance Speaker Interface
Flexible Bus Interface
16-Bit Data and Control Paths
Fast Access Time (40 ns)
Pipelined Data Path
Handles Block Word Transfers for Any
Alignment
High Performance Chained ("Back-toBack") Transmit and Receive
Flat Memory Structure for Low CPU
Overhead
Dynamic Memory Allocation Between
Transmit and Receive
Buffered Architecture, Insensitive to Bus
Latencies (No Overruns/Underruns)
Supports Boot PROM for Diskless ISA
Applications
Simultasking is a trademark and SMSC is a registered trademark of Standard Microsystems Corporation
TABLE OF CONTENTS
FEATURES ........................................................................................................................................1
PIN CONFIGURATION.......................................................................................................................3
GENERAL DESCRIPTION .................................................................................................................4
OVERVIEW ........................................................................................................................................4
PIN REQUIREMENTS ........................................................................................................................7
DESCRIPTION OF PIN FUNCTIONS .................................................................................................9
BUFFER TYPES ..............................................................................................................................16
FUNCTIONAL DESCRIPTION..........................................................................................................20
MODEM INTERFACE ......................................................................................................................23
BUFFER MEMORY ..........................................................................................................................24
INTERRUPT STRUCTURE...............................................................................................................32
RESET LOGIC .................................................................................................................................33
POWERDOWN LOGIC.....................................................................................................................34
INTERNAL VS EXTERNAL ATTRIBUTE MEMORY MAP ................................................................40
PCMCIA CONFIGURATION REGISTERS: ADDRESS 8000-803EH................................................41
PCMCIA CONFIGURATION REGISTERS DESCRIPTION ...............................................................42
INTERNAL I/O SPACE MAP ............................................................................................................52
I/O REGISTERS DESCRIPTION ......................................................................................................53
THEORY OF OPERATION ...............................................................................................................83
MAGIC PACKET SUPPORT ............................................................................................................84
INTERNAL VS. EXTERNAL ATTRIBUTE MEMORY MAP ...............................................................93
FUNCTIONAL DESCRIPTION OF THE BLOCKS.............................................................................97
BOARD SETUP INFORMATION ....................................................................................................106
OPERATIONAL DESCRIPTION .....................................................................................................111
TIMING DIAGRAMS ......................................................................................................................115
Related Documentation
1.
2.
3.
PCMCIA 5.0 standard (for multi-function extensions)
AT&T HSM288xCF Modem Chip Set Data Sheet - July 5, 1994, V.35 bis extension 1996
Rockwell ACL & ACFL series L39 based modem designer’s guide, 1994/95/97
2
•
Network Interface
•
•
Uses Certified LAN9000 Drivers for Major
Network Operating Systems
Software Driver Compatible with
LAN91C92, LAN91C94 and LAN91C100
(100 Mbps) and LAN91C110 (100 Mbps)
Controllers in ISA Mode
Software Driver Utilizes Full Capability of 32
Bit Microprocessor
PIN CONFIGURATION
100
99
98
97
102
101
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
LAN91C95
128 Pin TQFP
53
54
55
56
57
58
59
60
61
62
63
64
AVDD
TXP/nCOLL
TXN/nCRS
TPETXP
TEPTXDP
TPETXN
TPETXDN
AVSS
nTXLED/nTXEN
nRXLED/RXCLK
nLINKLED/TXD
nBSELED/RXD
VDD
SPKRIN
SPKROUT
nMIS16
MRDY
MINT
VSS
MRINGIN
nMRINGOA
MRINGOB
nMCS
nMRESET
VDD
MIDLEN1
nMPWDN
nMPDOUT
MFBK1
VSS
NC
ND
108
107
106
105
104
103
NC
AVSS
COLN
COLP
RECN
RECP
TPERXN
TPERXP
AVDD
AVSS
RBIAS
AVDD
nXENDEC
nEN16
PWRDWN/TXCLK
nROM/nPCMCIA
VSS
ENEEP
EESK
EECS
EEDO/SDOUT
EEDI
IOS2
IOS1
VDD
IOS0
XTAL2
XTAL1
WAKEUP
nWAKEUP_EN
RESET
NC
•
•
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
•
Software Drivers
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
•
•
Integrated 10BASE-T Transceiver
Functions:
Driver and Receiver
Link Integrity Test
Receive Polarity Detection and
Correction
Integrated AUI Interface
Implements 10 Mbps Manchester
Encoding/Decoding and Clock Recovery
Automatic Retransmission, Bad Packet
Rejection, and Transmit Padding
External and Internal Loopback Modes
NC
AEN/nREG
A0
A1
VDD
A2
A3
A4
A5
A6
A7
VSS
A8
A9
A10
A11
A12
A13
VDD
A14
A15
A16/nFWE
A17/nFCS
A18
A19/nCE1
VSS
D0
D1
D2
VDD
D3
NC
•
Four Direct Drive LED Outputs for Status/
Diagnostics
3
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
NC
NC
VSS
INTR3
INTR2/nSTSCHG
INTR1/nINPACK
INTR0/nIREQ
VDD
nIORD
nIOWR
nMEMR/nOE
nIOSC16/nIOIS16
VSS
IOCHRDY/nWAIT
BALE/nWE
nSBHE/nCE2
VDD
D15
D14
D13
D12
VSS
D11
D10
D9
VDD
D8
D7
D6
VSS
D5
D4
GENERAL DESCRIPTION
accessed with 40ns access times to any of its
registers, including its packet memory. No DMA
services are used by the LAN91C95; virtually
decoupling network traffic from local or system
bus utilization.
For packet memory
management, the LAN91C95 integrates a
unique hardware Memory Management Unit
(MMU) with enhanced performance and
decreased software overhead when compared to
ring buffer and linked list architectures. The
LAN91C95 is portable to different CPU and bus
platforms due to its flexible bus interface, flat
memory structure (no pointers), and its loosely
coupled buffered architecture (not sensitive to
latency).
The LAN91C95 is a VLSI Ethernet Controller
that combines ISA and PCMCIA interfaces, as
well as an interface to a companion modem chip
set, in one chip. The LAN91C95 integrates all
the MAC and physical layer functions as well as
the packet RAM needed to implement a high
performance 10BASE-T (twisted pair) node. For
10BASE5 (thick coax), 10BASE2 (thin coax),
and 10BASE-F (fiber) implementations, the
LAN91C95 interfaces to external transceivers
via its AUI port. Only one additional IC is
required on most applications.
The LAN91C95 occupies 16 I/O locations and
no memory space except for PCMCIA attribute
memory space. The same I/O space is used for
both ISA and PCMCIA operations.
The
LAN91C95 can directly interface the ISA and
PCMCIA buses and deliver no wait state
operation. Its shared memory is sequentially
The LAN91C95 interfaces directly with Rockwell
International L39/C39 controller-based modems
and Lucent Technologies’ HSM288xCF modem.
OVERVIEW
A unique architecture allows the LAN91C95 to
combine high performance, flexibility, high
integration and simple software interface.
I/O decoders are included in the LAN91C95’s
PCMCIA interface, with independent decoders
for the LAN and for the modem functions.
The LAN91C95 incorporates the LAN91C92/4
functionality for ISA environments with several
new features, as well as a PCMCIA interface
and attribute registers that comply with the
PCMCIA Multi-Function specification.
Mode
selection between ISA and PCMCIA is static and
is done only once at the end of power on reset.
The LAN91C95 consists of the same logical I/O
register structure in ISA and PCMCIA modes.
However, some of the signals used to access
the PCMCIA differ from the ISA mode.
Additional registers exist in the PCMCIA
attribute space. The ROM memory space only
exists in ISA mode and the attribute space only
exists in PCMCIA mode.
These decoders are used whenever the
LAN91C95 is used as a multi-function card, and
they can be bypassed when only one function is
enabled. The LAN91C95 also merges the LAN’s
internal interrupt source with the external
modem interrupt connected to the LAN91C95.
The MMU (Memory Management Unit)
architecture used by the LAN91C95 combines
the simplicity and low overhead of fixed areas
with the flexibility of linked lists providing
improved performance over other methods.
The LAN91C95 is designed to support full
duplex switched Ethernet where transmit and
4
receive are fully independent. It has 6 kbytes of
internal memory and the MMU manages
memory in 256 byte pages. The memory size
accommodates the increase in interrupt latency
resulting from simultaneous LAN and modem
operation as well as the potential for
simultaneous transmit and receive traffice in
some full duplex applications.
The LAN91C95 integrates most of the 802.3
functionality, incorporating the MAC layer
protocol, the physical layer encoding and
decoding functions with the ability to handle the
AUI interface. For twisted pair networks, the
LAN91C95
integrates
the
twisted
pair
transceiver as well as the link integrity test
functions.
Packet reception and transmission are
determined by memory availability. All other
resources are always available if memory is
available.
To complement this flexible
architecture, all ISA bus interface functions are
incorporated in the LAN91C95, as well as a 6K
byte packet RAM and serial EEPROM-based
setup.
The user can select or modify
configuration choices.
The LAN91C95 is a true 10BASE-T single chip
able to interface a system or a local bus.
The LAN91C95 stores the Configuration
Information Structure (CIS) on reset or power-up
from the serial EEPROM. This allows the host
to access data to allow the setup of the PCMCIA
multi-function card.
High integration:
Single chip adapter including:
Packet RAM
ISA bus interface
PCMCIA interface
EEPROM interface
Encoder decoder with AUI interface
Full duplex, magic packet 10BASE-T
transceiver
Lucent Technologies and Rockwell
International modem interface
Directly-driven LEDs for installation and runtime diagnostics are provided, as well as 802.3
statistics gathering to facilitate network
management.
The LAN91C95 offers:
In ISA mode, the serial EEPROM acts as
storage for configuration and IEEE Ethernet
address information compatible with the existing
LAN9000 family of ISA Ethernet controllers.
In PCMCIA mode, the serial EEPROM stores
the CIS, as well as the IEEE address,
information, but it does not store any I/O or IRQ
information since this information is handled by
the host’s socket controller.
For CIS
requirements above 512 bytes, an optional
external parallel EEPROM can be used in
conjunction with the internal CIS. This allows
additional external, non-volatile storage for
applications that require XIP and use the
modem function. If the serial EEPROM is not
used in PCMCIA mode, the parallel EEPROM
must be used.
In this case, the parallel
EEPROM is selected for the first 512 bytes of
storage as well, allowing the CIS to be stored in
the parallel EEPROM and, on power-up, to be
read directly by the host. The remaining parallel
EEPROM can be used for XIP applications, if
needed.
High performance:
Chained (“back-to-back”) packet handling
with no CPU intervention:
Queues transmit packets
Queues receive packets
Full duplex operation for higher network
throughput
Stores results in memory along with
packet
Queues Ethernet and modem interrupts
Optional single interrupt upon
completion of transmit chain
Fast block move operation for load/unload:
CPU sees packet bytes as if stored
contiguously
Handles 16 bit transfers regardless of
address alignment
Access to packet through fixed window
5
Resource allocation:
Memory dynamically allocated for transmit
and receive
Can automatically release memory on
successful transmission
Fast bus interface:
Compatible with ISA type and faster buses
Flexibility:
Flexible packet and header processing:
Can be set to Simultasking - Early
Receive and transmit modes
Can access any byte in the packet
Can immediately remove undesired
packets from queue
Can move packets from receive to
transmit queue
Can alter receive processing order
without copying data
Can discard or enqueue again a failed
transmission
Configuration:
ISA:
Uses non-volatile jumperless setup via
serial EEPROM
PCMCIA:
Uses serial EEPROM for attribute
memory storage. PCMCIA I/O ignores
address lines A4-A15 and relies on the
PCMCIA host, decoding for the slot
nROM/nPCMCIA on the LAN91C95 is left
open with a pullup for ISA mode. This pin
is sampled at the end of Power On Reset.
If found low, the LAN91C95 is configured
for PCMCIA mode.
6
PIN REQUIREMENTS
FUNCTION
SYSTEM ADDRESS BUS
SYSTEM DATA BUS
SYSTEM CONTROL BUS
MODEM INTERFACE
SERIAL EEPROM
NUMBER OF
PINS
ISA
PCMCIA
A0-A15
A16
A17
A18
A19
AEN
A0-A15
nFWE
nFCS
D0-D15
D0-D15
16
RESET
BALE
nIORD
nIOWR
nMEMR
IOCHRDY
nIOCS16
nSBHE
INTR0
INTR1
INTR2
INTR3
RESET
nWE
nIORD
nIOWR
nOE
nWAIT
nIOIS16
nCE2
nIREQ
nINPACK
nSTSCHG
12
nMRESET
MINT
nMCS
MRDY
nMPWDN
MIDLEN1
MRINGIN
nMRINGOA
MRINGOB
SPKRIN
SPKROUT
nMPDOUT
MFBK1
nMIS16
nMRESET
MINT
nMCS
MRDY
nMPWDN
MIDLEN1
MRINGIN
nMRINGOA
MRINGOB
SPKRIN
SPKROUT
nMPDOUT
MFBK1
nMIS16
14
EEDI
EEDO
EECS
EESK
ENEEP
IOS0
IOS1
IOS2
EEDI
EEDO
EECS
EESK
ENEEP
IOS0
IOS1
IOS2
8
21
nCE1
nREG
7
FUNCTION
NUMBER OF
PINS
ISA
PCMCIA
CRYSTAL OSC.
XTAL1
XTAL2
XTAL1
XTAL2
2
POWER
VDD
AVDD
VDD
AVDD
12
GROUND
GND
AGND
GND
AGND
12
TPERXP
TPERXN
TPETXP
TPETXN
TPETXDP
TPETXDN
TPERXP
TPERXN
TPETXP
TPETXN
TPETXDP
TPETXDN
6
RECP
RECN
COLP
COLN TXP/nCOLL
TXN/nCRS
RECP
RECN
COLP
COLN
TXP/nCOLL
TXN/nCRS
6
LEDs
nLNKLED/TXD
nRXLED/RXCLK
nBSELED/RXD
nTXLED/nTXEN
nLNKLED/TXD
nRXLED/RXCLK
nBSELED/RXD
nTXLED/nTXEN
4
MISC.
RBIAS
WAKEUP
nWAKEUPEN
PWRDWN/TXCLK
nXENDEC
nEN16
ROM/nPCMCIA
RBIAS
WAKEUP
nWAKEUPEN
PWRDWN/TXCLK
nXENDEC
nEN16
ROM/nPCMCIA
7
10BASE-T INTERFACE
AUI INTERFACE
TOTAL PINS
120
8
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
NAME
113
SYMBOL
TYPE
DESCRIPTION
nROM/
nPCMCIA
I/O4 with
pullup
This pin is sampled at the end of RESET.
When this pin is sampled low the LAN91C95
is configured for PCMCIA operation and all pin
definitions correspond to the PCMCIA mode.
For ISA operation this pin is left open and is
used as a ROM chip select output that goes
active when nMEMR is low and the address
bus contains a valid ROM address.
35, 36,
38-43,
45-50,
52, 53
Address 015
A0-A15
I
Input address lines 0 through 15.
54
Address 16
A16
I
ISA - Input address line 16.
nFWE
O4
Address 17
A17
I
nFlash
Memory
Chip Select
nFCS
O4
56
Address 18
A18
I
57
Address 19
A19
I with pullup
Card Enable
1
nCE1
Address
Enable
AEN
nFlash
Memory
Write
55
34
PCMCIA - Output. Flash Memory Write
Enable used for programming the attribute
memory. Goes active (low) when nWE=0 and
WRATTRIB=1 (in ECOR bit 3).
ISA - Input address line 17.
PCMCIA - Output. Flash Memory Chip Select
used to access attribute memory. Goes active
(low) when nREG=0, nCE1=0 and A15=0.
Input address line 18.
PCMCIA - Card Enable 1 input. Used to select
card on even byte accesses.
I with pullup
nREG
81
nByte High
Enable
nCard
Enable 2
nSBHE
ISA - Input address line 19.
ISA - Address enable input. Used as an
address qualifier. Address decoding is only
enabled when AEN is low.
PCMCIA - Attribute memory and IO select
input. Asserted when the card attribute space
or IO space is being accessed.
I with pullup
nCE2
ISA - Byte High Enable input. Asserted (low)
by the system to indicate a data transfer on
the upper data byte.
PCMCIA - Card Enable 2 input. Used to select
card on odd byte accesses.
9
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
SYMBOL
TYPE
DESCRIPTION
Ready
IOCHRDY
OD24 with
pullup
ISA - Output. Optionally used by the
LAN91C95 to extend host cycles.
nWait
nWAIT
Data Bus
D0-D15
I/O24
Bidirectional. 16 bit data bus used to access
the LAN91C95 internal registers. The data bus
has weak internal pullups. Supports direct
connection to the system bus without external
buffering.
98
Reset
RESET
IS with
pullup
Input. Active high Reset. This input is not
considered active unless it is active for at least
100ns to filter narrow glitches. A POR circuit
generates an internal reset upon power up for
at least 15msec. All hardware reset references
in this spec relate to the OR function of the
POR and the RESET pin.
82
Address
Latch
BALE
IS with
pullup
ISA - Input. Address strobe. For systems that
require address latching, the falling edge of
BALE latches address lines and nSBHE.
nWrite
Enable
nWE
Interrupt
INTR0
nInterrupt
Request
nIREQ
Interrupt 1
INTR1
83
59, 60,
61, 63,
65, 66,
68-70,
72-74,
76-79
90
91
NAME
PCMCIA - Output. Optionally used by the
LAN91C95 to extend host cycles.
PCMCIA - Write Enable input. Used for writing
into COR and CSR registers as well as
attribute memory space.
O24
ISA - Active high interrupt signal. The interrupt
line selection is determined by the value of INT
SEL1-0 bits in the Configuration Register. This
interrupt is tri-stated when not selected.
PCMCIA - Active low interrupt request output.
Pin acts as a Ready pin during power-up. The
pin should be pulled low within 10us of the
application of the VCC or Reset (which ever
occurs later). It remains low(0) until the CIS is
loaded in the Internal SRAM. The high(1)
state indicates to the host controller that the
device is ready.
O24
10
ISA - Output. Active high interrupt signal. The
interrupt line selection is determined by the
value of INT SEL1-0 bits in the Configuration
Register. This interrupt is tri-stated when not
selected.
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
NAME
SYMBOL
TYPE
nINPACK
92
DESCRIPTION
PCMCIA - Output asserted to acknowledge
read cycles for an enabled function.
Interrupt 2
INTR2
O24
ISA - Output. Active high interrupt signal. The
interrupt line selection is determined by the
value of INT SEL1-0 bits in the Configuration
Register. This interrupt is tri-stated when not
selected.
nStatus
Changed
nSTSCHG
93
Interrupt 3
INTR3
O24
ISA - Output. Active high interrupt signal. The
interrupt line selection is determined by the
value of INT SEL1-0 bits in the Configuration
Register. This interrupt is tri-stated when not
selected.
85
nI/O16
nIOCS16
OD24
ISA - Active low output asserted in 16 bit
mode when AEN is low and A4-A15 decode to
the LAN91C95 address programmed into the
high byte of the Base Address Register.
PCMCIA - Status changed bit. Depending on
the setting of the RingEn bit (Modem CCSR),
this pin either reflects the ringing status (ExCA
mode) or the state of the Modem Changed bit.
The ringing status is obtained by stretching the
MRINGIN to convert a 20Hz toggle rate to a
constant level.
nIOIS16
PCMCIA - Active low output asserted
whenever the LAN91C95 is in 16 bit mode,
and “Enable Function” bit in the ECOR register
is high, nREG is low and A4-A15 decode to
the LAN address specified in I/O Base
Registers 0 and 1 in PCMCIA attribute space.
88
nI/O Read
nIORD
IS with
pullup
Input. Active low read strobe used to access
the LAN91C95 IO space.
87
nI/O Write
nIOWR
IS with
pullup
Input. Active low write strobe used to access
the LAN91C95 IO space.
86
nMemory
Read
nMEMR
IS with
pullup
ISA - Active low signal used by the host
processor to read from the external ROM.
nOutput
Enable
nOE
PCMCIA - Output Enable input used to read
from the COR, CSR and attribute memory.
11
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
NAME
SYMBOL
TYPE
DESCRIPTION
24
nModem
Reset
nMRESET
O4
Reset output to Modem. Asserted whenever
RESET pin is high, internal POR is active, or
SRESET bit is high (MCOR bit 7).
18
Modem
Interrupt
MINT
I with pull
down
Interrupt input from Modem. Reflected in INTR
(CSR bit 1) and asserts the appropriate
interrupt pin if enabled.
23
nModem
Chip Select
nMCS
O4
17
Modem
Ready
MRDY
I with pullup
Modem ready input. Low indicates the modem
is not ready, either after reset or exiting from
stop or sleep modes.
27
nModem
Powerdown
nMPWDN
O4
Powerdown output to modem controller. This
pin is active (low) when either the PWRDWN
bit (CSR bit 2) is set or the modem is disabled
(not configured).
MIDLEN1
O4
Powerdown output to modem controller. This
pin is active (high) when either the PWRDWN
bit (CSR bit 2) is set or the modem is disabled
(not configured).
26
Chip select output to modem.
20
Modem Ring
Input
MRINGIN
I
Ring input from the modem controller. Toggles
when ringing, low when not ringing.
21
nModem
Ring Output
A
nMRINGOA
O4
Ring output signal. When there is no ringing
on the MRINGIN pin and the modem is not in
Powerdown mode this output is high. During
ringing this signal is the inverse of the
MRINGIN input. When the PWRDWN bit is
set or the function is disabled, this output is
low. This signal is activated about 12 msec
after removing Powerdown.
22
Modem Ring
Output B
MRINGOB
O4
Ring output signal. When the modem is not in
Powerdown mode (PWRDWN bit is zero and
the function is enabled) this output follows the
value of the MRINGIN input. When entering
Powerdown mode, a rising edge is generated
on the pin. A rising edge is also generated
when exiting Powerdown mode also. Refer to
Figure 2.
14
Speaker
Input
SPKRIN
I with pullup
Speaker Input. This is a digitized (single level)
audio input from the modem controller.
12
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
SYMBOL
TYPE
DESCRIPTION
SPKROUT
O4 tri-stable
with pullup
Speaker Output. This pin reflects the SPKRIN
pin when enabled by the AUDIO bit (Modem
CSR bit 3). When disabled this pin is tristated.
28
nMPDOUT
I Schmitt
Used to control Powerdown mode. Tie to a
180K pull-up and a 0.1uF cap to ground.
Tie high when not used. This signal is used
in the RC time constant.
29
MFBK1
O4 with
pullup
Tie to nMPDOUT through a 5.1M resistor.
This signal is used in the RC time constant
in conjuction with the nMPDOUT pin.
nMIS16
I with pullup
Input. When low, it indicates a 16 bit modem,
otherwise the modem is 8 bit wide. Used to
determine if nIOIS16 (PCMCIA) and nIOCS16
(ISA) need to be asserted for modem cycles.
The value of this pin may change from cycle to
cycle.
15
NAME
Speaker
Output
16
n16 Bit
Modem
110
EEPROM
Clock
EESK
O4
Output. 4µs clock used to shift data in and out
of the serial EEPROM.
109
EEPROM
Chip Select
EECS
O4
Output. Serial EEPROM chip select.
108
EEPROM
Data Out
EEDO/
SDOUT
O4
Output. Connected to the DI input of the serial
EEPROM.
107
EEPROM
Data In
EEDI
I with pulldown
Input. Connected to the DO output of the serial
EEPROM.
103,
105, 106
I/O Base
IOS0-IOS2
I with pullup
Input. External switches can be connected to
these lines to select between predefined
EEPROM configurations. The values of these
pins are readable. These pins are used in ISA
mode only. If in PCMCIA mode, these pins are
not used.
9
nTransmit
LED
nTXLED
OD16
Internal ENDEC - Transmit LED output.
nTransmit
Enable
nTXEN
O162
External ENDEC - Active low Transmit Enable
output.
13
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
SYMBOL
TYPE
DESCRIPTION
nBSELED
OD16
Internal ENDEC - Board Select LED activated
by accesses to I/O space (nIORD or nIOWR
active with AEN low and valid address decode
for ISA, and with nREG low and and “Enable
Function” bit in the ECOR register is high for
PCMCIA). The pulse is stretched beyond the
access duration to make the LED visible.
Receive
Data
RXD
I with pullup
nReceive
LED
nRXLED
OD16
Internal ENDEC - Receive LED output.
Receive
Clock
RXCLK
I with pullup
External ENDEC - Receive clock input.
nLNKLED
OD16
Internal ENDEC - Link LED output.
Transmit
Data
TXD
0162
External ENDEC - Transmit Data output.
111
Enable
EEPROM
ENEEP
I with pullup
Input. This active high input enables the
EEPROM to be read or written by the
LAN91C95. Internally pulled up. Must be
connected to ground if no serial EEPROM is
used. In PCMCIA mode, a parallel EEPROM
is required if no serial EEPROM is used.
115
nEnable 16
Bit
nEN16
I with pullup
Input. When low the LAN91C95 is configured
for 16 bit bus operation. If left open the
LAN91C95 works in 8 bit bus mode. 16 bit
configuration can also be programmed via
serial EEPROM (In ISA Mode only) or via
software initialization of the CONFIGURATION
REGISTER.
101
Crystal 1
XTAL1
Iclk
102
Crystal 2
XTAL2
An external parallel resonance 20 MHz crystal
should be connected across these pins. If an
external clock source is used, it should be
connected to XTAL1 and XTAL2 should be left
open.
123
AUI Receive
RECP
12
10
11
124
NAME
nBoard
Select LED
nLink LED
Diff. Input
RECN
14
External ENDEC - NRZ receive data input.
AUI receive differential inputs.
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
NAME
SYMBOL
TYPE
DESCRIPTION
2
3
AUI Transmit
TXP/nCOLL
TXN/nCRS
Diff.
Output
Internal ENDEC - (nXENDEC pin open). In
this mode TXP and TXN are the AUI transmit
differential outputs. They must be externally
pulled up using 150 ohm resistors.
I
External ENDEC - (nXENDEC pin tied low). In
this mode the pins are inputs used for collision
and carrier sense functions.
125
126
AUI Collision
COLP
COLN
Diff. Input
AUI collision differential inputs. A collision is
indicated by a 10 MHz signal at this input pair.
121
122
TPE Receive
TPERXP
TPERXN
Diff. Input
10BASE-T receive differential inputs.
4
6
TPE
Transmit
TPETXP
TPETXN
Diff. Output
Internal ENDEC differential outputs.
5
7
TPE
Transmit
Delayed
TPETXDP
TPETXDN
Diff. Output
10BASE-T delayed transmit differential
outputs. Used in combination with TPETXP
and TPETXN to generate the 10BASE-T
transmit pre-distortion.
Powerdown
PWRDWN
I with pullup
Internal ENDEC - Powerdown input. It keeps
the LAN91C95 in powerdown mode when high
(open). Must be low for normal operation.
Refer to the Powerdown Matrix following for
further details.
114
10BASE-T
transmit
Transmit
Clock
TXCLK
External ENDEC - Transmit clock input from
external ENDEC
99
nWakeup
Enable
nWAKEUPEN
I with pullup
Input. When pulled down, the device will
enable Magic Packet (MP) logic and put the
Ethernet function in powerdown mode. The pin
assertion will override the state of
WAKEUP_EN and PWRDN bits in CTR,
Pwrdwn bit in ECSR, and Enable Function bit
ECOR. When deasserted, the WAKEUP_EN
and PWRDN bits will be changed to (0),
Pwrdwn to (0), and Enable Function to (1).
100
Wakeup
WAKEUP
O4
Output. Asserted high if nWAKEUP_EN is
asserted and a valid Magic Packet (MP)
pattern is detected. The pin remains asserted
until nWAKEUP_EN is deasserted.
15
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
NAME
SYMBOL
TYPE
DESCRIPTION
118
Bias Resistor
RBIAS
Analog Input
A 39 kohm 1% resistor should be connected
between this pin and analog ground.
116
nExternal
ENDEC
nXENDEC
I with pullup
When tied low the LAN91C95 is configured for
external ENDEC. When tied high or left open
the LAN91C95 will use its internal
encoder/decoder.
13, 25,
37, 51,
62, 71,
80, 89,
104
Power
VDD
1, 117,
120
Analog
Power
AVDD
19, 30,
44, 58,
67, 75,
84, 94,
112
Ground
VSS
8, 119,
127
Analog
Ground
AVSS
+5V power supply pins
+5V analog power supply pins
Ground pins
Analog ground pins
BUFFER TYPES
O4
O162
O24
OD16
OD24
I/O24
I
IS
Iclk
Output buffer with 2mA source and 4mA sink
Output buffer with 2mA source and 16mA sink
Output buffer with 12mA source and 24mA sink
Open drain buffer with 16mA sink
Open drain buffer with 24mA sink
Bidirectional buffer with 12mA source and 24mA sink
Input buffer with TTL levels
Input buffer with Schmitt Trigger Hysteresis
Clock input buffer
16
nIRQ
BUFFER
SYSTEM BUS
17
ADDRESS
PROM
DATA
3
N/C
XTAL1
EEDI
EEDO
EESK
IOS1 IOS2 nEN16 ENEEP
TPETXDP
TPETXN
TPETXP
A0-19
D0-15
nMEMR
nROM
4
INTR0-3
RBIAS
COLN
COLP
RECN
RECP
TXN
TXP
TPERXN
TPERXP
LAN91C95
IOS0
TPETXDN
IOCHRDY
EECS
4
nIORD, nIOWR,
nIOCS16
XTAL2
4
DIAGNOSTIC
LEDs
nSBHE
RESET
BALE
AEN
20 MHz
EEPROM
SERIAL
10BASET
AUI
CABLE SIDE
FIGURE 1 - LAN91C95 SYSTEM BLOCK DIAGRAM FOR ISA BUS WITH BOOT PROM
P
C
M
C
I
A
C
o
n
n
e
c
t
o
r
nCE1, nCE2, nREG, nWE
A0-9, A15
10BASE-T / AUI
INTERFACE
D0-15
nIORD, nIOWR MRDY
nMCS
RESET
nMRESET
STSCHG
MINT
nIREQ 91C95
nIOIS16, nINPACK
nWAIT
SPKROUT
nOE
nFWE
nFCS
MRINGIN
SPKRIN
MRINGOnA/B
nPWDN
RDY
nCS
nRESET
INT
PHONE LINE
Modem
Chip Set
RING
SPKR
MRINGOnA/B
PWDN
A0-2 (/A0-9, A15)
D0-7 (/D0-15)
nOE nWEnCE
CS,SK,DI,DO
D0-7 Extended
Serial EEPROM
Attribute
A0-8 PROM
2816
(Optional)
(ISA-93C46)
(PCMCIA-93C66)
FIGURE 2 - LAN91C95 SYSTEM BLOCK DIAGRAM FOR DUAL FUNCTION PCMCIA CARD
18
MODEM
INTERFACE
DATA
BUS
ADDRESS
BUS
MANAGEMENT
ARBITER
CSMA/CD
ENDEC
AUI
BUS
INTERFACE
CONTROL
MMU
TWISTED PAIR
TRANSCEIVER
RAM
FIGURE 3 - LAN91C95 INTERNAL BLOCK DIAGRAM
19
10BASE-T
FUNCTIONAL DESCRIPTION
The Ethernet controller function includes a built-in
The LAN91C95 consists of an integrated Ethernet
6kbyte RAM for packet storage. This RAM buffer is
controller mapped entirely in I/O space, as well as
accessed by the CPU through two sequential
support for an external Modem controller also
access regions of 3 kbytes each. The RAM access
mapped in I/O space. In addition, PCMCIA attribute
is internally arbitrated by the LAN91C95 and
memory space is decoded to interface an external
dynamically allocated between transmit and
CIS ROM, with configuration registers as per
receive packets using 256 byte pages. The
PCMCIA 3.X extensions implemented on-chip in
Ethernet controller functionality is identical to the
attribute space above the CIS ROM decode area.
LAN91C94 except where indicated otherwise.
The PCMCIA Configuration Registers are also
accessible in I/O space to allow non-PCMCIA dual
function designs.
Table 1 - Bus Transactions In Isa Mode
A0
nSBHE
D0-D7
D8-D15
0
X
even byte
-
(16 BIT=0)
1
X
odd byte
-
16 BIT MODE
0
0
even byte
odd byte
otherwise
0
1
even byte
-
1
0
-
odd byte
1
1
8 BIT MODE
(nEN16=1)
20
invalid cycle
Table 2 - Bus Transactions In PCMCIA Mode
A0
nCE1
nCE2
D0-D7
D8-D15
0
0
X
even byte
-
1
0
X
odd byte
-
X
1
X
16 BIT MODE
0
0
0
even byte
odd byte
otherwise
0
0
1
even byte
-
1
0
1
odd byte
X
1
0
-
X
1
1
8 BIT MODE
((IOis8=1) + (nEN16=1).(16BIT=0))
NO CYCLE
odd byte
NO CYCLE
16BIT = CONFIGURATION REGISTER bit 7
IOis8 = ECSR register bit 5
nEN16 = pin nEN16
For the modem function, the transactions are similarxcept that the modem is assumed to be 8 bit wide
unless (IOis8=0) and (nMIS16=0).
Note: The IOis8 value should be identical in MCSR and ECSR if both functions are enabled.
8 Bit mode = (IOis8=1)+(nMIS16=1)
21
Table 3 - LAN91C95 Address Spaces
SIGNALS USED ISA PCMCIA ON-CHIP
DEPTH
WIDTH
Up to 32k
locations, only
even bytes are
usable
8 bits on even
addresses
Y
64 locations, only
even bytes are
usable
8 bits
Y
N
8 locations
8 bit
Y
Y
16 locations
8 or 16 bits
PCMCIA
Attribute
Memory
nOE/nWE
N
Y
N
(external
ROM)
PCMCIA
Configuration
Registers
nOE/nWE
N
Y
Modem I/O
Space
nIORD/nIOWR
Y
Ethernet I/O
Space (1)
nIORD/nIOWR
Y
(1) This space also allows access to the PCMCIA Configuration Register through Banks 4 and 5 (LAN91C95
only).
Device configuration is done using a serial
EEPROM, with support for modifications to the
EEPROM at installation time. A Flash ROM is
supported for PCMCIA attribute memory.
Except for the bus interface, the functional behavior
of the LAN91C95 after initial configuration is
identical for ISA and PCMCIA modes.
The LAN91C95 includes an arbitrated shared
memory of 6 kbytes accessed by the CPU. The
MMU unit allocates RAM memory to be used for
transmit and receive packets, using 256 byte
pages.
The CSMA/CD core implements the 802.3 MAC
layer protocol. It has two independent interfaces,
the data path and the control path. Both interfaces
are 16 bits wide.
The control path provides a set of registers used to
configure and control the block. These registers
are accessible by the CPU through the
LAN91C95’s I/O space. The data path is of
sequential access nature and typically works in one
direction at any given time. An internal DMA type
of interface connects the data path to the device
RAM through the arbiter and MMU.
The arbitration is transparent to the CPU in every
sense. There is no speed penalty for ISA type of
machines due to arbitration.
There are no
restrictions on what locations can be accessed at
any time. RAM accesses as well as MMU requests
are arbitrated.
The RAM is accessed by mapping it into I/O space
for sequential access.
Except for the RAM
accesses and the MMU request/release
commands, I/O accesses are not arbitrated.
The CSMA/CD data path interface is not accessible
to the host CPU.
The internal DMA interface can arbitrate for RAM
access and request memory from the MMU when
necessary.
The I/O space is 16 bits wide. Provisions for 8 bit
systems are handled by the bus interface.
In the system memory space, up to 64 kbytes are
decoded by the LAN91C95 as expansion ROM.
The ROM expansion area is 8 bits wide.
An encoder/decoder block interfaces the CSMA/CD
block on the serial side. The encoder will do the
Manchester encoding of the transmit data at 10
22
Mbps, while the decoder will recover the receive
clock and decode received data.
Modem Interface
LAN91C95 provides seemless interface to the
Lucent HSM288xCF and Rockwell ACL and
ACFL series modems. The controller provides
all PCMCIA 5.0 registers needed to support the
modem function.
These registers include
support for:
Carrier and Collision detection signals are also
handled by this block and relayed to the CSMA/CD
block.
The encoder/decoder block can interface the
network through the AUI interface pairs or it can be
programmed to use the internal 10BASE-T
transceiver and connect to a twisted pair network.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Function Enable/Disable
Power Down/Up
Function Reset
Modem Ready/Busy indication
Data Bus Access Width
I/O Base Select
I/O Access Range
Interrupt Enable
Wake
up
events
‘Status
Change’
information and routing to nSTSCHG pin
10. Audio Path Mute Control
The twisted pair interface takes care of the medium
dependent signaling for 10BASE-T type of
networks. It is responsible for line interface (with
external pulse transformers and pre-distortion
resistors), collision detection as well as the link
integrity test function.
The LAN91C95 provides a 16 bit data path into
RAM. The RAM is private and can only be
accessed by the system via the arbiter. RAM
memory is managed by the MMU. Byte and word
accesses to the RAM are supported.
Among other functions, the LAN91C95 also
provides Power-On Reset to the modem. The
data sheet specifies 0.1mF capacitor and
180KW resistor at the nMPDOUT pin assuming
a minimum of 15msec modem reset - required
for the modem. The duration of this POR can
be changed with the RC value connected with
the LAN91C95 nMPDOUT pin.
If the system to SRAM bandwidth is insufficient, the
LAN91C95 will automatically use its IOCHRDY line
for flow control.
However, for ISA buses,
IOCHRDY will never be negated.
The LAN91C95 decodes the host address bus
and asserts chip select for the specified modem
I/O range provided the function is enabled and
powered up.
The modem chips’ internal
registers are accessed via the I/O interface only.
PCMCIA registers for the modem, however, can
be accessed via the PCMCIA configuration
memory space or the LAN91C95 control
registers I/O space through Bank 5.
23
All accesses to the RAM are done via I/O space. A
bit in the address pointer also specifies if the
address refers to the TX or RX area.
BUFFER MEMORY
The logical addresses for RAM access are divided
into TX area and RX area. Each one of the areas
is 1.536 kbytes long and accommodates one
maximum size Ethernet packet.
In the TX area, the host CPU has access to the
next transmit packet being prepared for
transmission. In the RX area, it has access to the
first receive packet not processed by the CPU yet.
The TX area is seen by the CPU as a window
through which packets can be loaded into memory
before queuing them in the TX FIFO of packets.
The TX area can also be used to examine the
transmit
completion
status
after
packet
transmission.
The FIFO of packets, existing beneath the TX and
RX areas, is managed by the MMU. The MMU
dynamically allocates and releases memory to be
used by the transmit and receive functions.
The MMU related parameters for the LAN91C95
are:
The RX area is associated to the output of the RX
FIFO of packets, and is used to access receive
packet data and status information.
RAM size
Max. number of packets
Max. pages per packet
Max. number of pages
Page size
The logical address is specified by loading the
address pointer register.
The pointer can
automatically increment on accesses.
24
6 kbytes (internal)
24
6
24
256 bytes
PHYSICAL
MEMORY
RCV
BIT
POINTER
REGISTER
TX PACKET
NUMBER
11-BIT
LOGICAL
ADDRESS
RCV VS. TX
AREA
SELECTION
PAGE =
256 bytes
2K TX
AREA
MMU
RX PACKET
NUMBER
2K RX
AREA
MMU
FIGURE 4 - MAPPING AND PAGING VS. RECEIVE AND TX AREA
25
PACKET NUMBER
REGISTER
STATUS
MEMORY
COUNT
PACKET #A
CPU
SIDE
DATA
B
STATUS
A
TX FIFO
COUNT
DATA
PACKET #B
C
TO
CSMA
B
STATUS
TX COMPLETION
FIFO
COUNT
PACKET #C
C
DATA
FIFO PORTS
REGISTER
LINEAR ADDRESS
MMU MAPPING
FIGURE 5 - TRANSMIT QUEUES AND MAPPING
26
MEMORY
FIFO PORTS
REGISTER
STATUS
D
COUNT
PACKET #D
DATA
E
CPU
SIDE
RX FIFO
STATUS
D
COUNT
PACKET #E
DATA
E
FROM
CSMA
LINEAR ADDRESS
MMU MAPPING
FIGURE 6 - RECEIVE QUEUE AND MAPPING
27
FIGURE 7 - LAN91C95 INTERNAL BLOCK DIAGRAM WITH DATA PATH
28
CONTROL
ADDRESS
BUS
DATA BUS
WRITE
DATA
REG.
READ
DATA
REG.
BUS INTERFACE
EEPROM
INTERFACE
EEPROM
DATA
DMA
ADDRESS
MMU
ARBITER
RX
FIFO
BUFFER RAM
TX
COMPL
FIFO
TX
FIFO
CSMA/CD
TRANSCEIVER
TWISTED PAIR
ENDEC
10BASET
AUI
used to specify the total number of bytes, and
that in turn is followed by the data area. The
data area holds the packet itself, and its length
is determined by the byte count. The packet
memory format is word oriented.
PACKET FORMAT IN BUFFER MEMORY
The packet format in memory is similar for the
TRANSMIT and RECEIVE areas. The first word
is reserved for the status word, the next word is
bit0
bit15
RAM
OFFSET
(DECIMAL)
0
2
S TAT U S W O R D
B Y T E C O U N T ( a lways even)
RESERVED
4
DATA AREA
1536 Max
CONTROL BYTE
L A S T D ATA BYTE (if odd)
FIGURE 8 - DATA PACKET FORMAT
STATUS WORD
BYTE COUNT
DATA AREA
CONTROL BYTE
TRANSMIT PACKET
Written by CSMA upon transmit
completion (see Status
Register)
Written by CPU
Written by CPU
Written by CPU to control
ODD/EVEN data bytes
29
RECEIVE PACKET
Written by CSMA upon receive
completion (see RX Frame
Status Word)
Written by CSMA
Written by CSMA
Written by CSMA. Also has
ODD/EVEN bit
BYTE COUNT - Divided by two, it defines the
total number of words including the STATUS
WORD, the BYTE COUNT WORD, the DATA
AREA and the CONTROL BYTE.
The data area contains six bytes of DESTINATION
ADDRESS followed by six bytes of SOURCE
ADDRESS, followed by a variable-length number
of bytes. On transmit, all bytes are provided by the
CPU, including the source address. The LAN91C95
does not insert its own source address. On receive,
all bytes are provided by the CSMA side.
The receive byte count always appears as even;
the ODDFRM bit of the receive status word
indicates if the low byte of the last word is relevant.
The 802.3 Frame Length word (Frame Type in
Ethernet) is not interpreted by the LAN91C95. It is
treated transparently as data both for transmit and
receive operations.
The transmit byte count least significant bit will be
assumed 0 by the controller regardless of the value
written in memory.
DATA AREA - The data area starts at offset 4 of
the packet structure and can extend up to 1536
bytes.
X
X
ODD
CONTROL BYTE - The CONTROL BYTE
always resides on the high byte of the last word.
For transmit packets the CONTROL BYTE is
written by the CPU as:
CRC
0
ODD - If set, indicates an odd number of bytes,
with the last byte being right before the CONTROL
BYTE. If clear, the number of data bytes is even
and the byte before the CONTROL BYTE is not
transmitted.
0
1
ODD
0
0
0
CRC - When set, CRC will be appended to the
frame. This bit has only meaning if the NOCRC bit
in the TCR is set.
For receive packets the CONTROL BYTE is written
by the controller as:
0
0
ODD - If set, indicates an odd number of bytes,
with the last byte being right before the CONTROL
BYTE. If clear, the number of data bytes is even
0
0
0
and the byte before the CONTROL BYTE should
be ignored.
30
RECEIVE FRAME STATUS WORD
This word is written at the beginning of each receive frame in memory. It is not available as a register.
HIGH
BYTE
ALGN
ERR
BROD
CAST
BAD
CRC
LOW
BYTE
5
ODD
FRM
TOOLNG
HASH VALUE
3
2
4
ALGNERR - Frame had alignment error.
TOO
SHORT
MULT
CAST
1
0
HASH VALUE - Provides the hash value used to
index the Multicast Registers. Can be used by
receive routines to speed up the group address
search. The hash value consists of the six most
significant bits of the CRC calculated on the
Destination Address, and maps into the 64 bit
multicast table. Bits 5,4,3 of the hash value select a
byte of the multicast table, while bits 2,1,0
determine the bit within the byte selected.
BRODCAST - Receive frame was broadcast.
BADCRC - Frame had CRC error.
ODDFRM - This bit when set indicates that the
received frame had an odd number of bytes.
TOOLNG - The received frame is longer than
802.3 maximum size (1518 bytes on the cable).
Examples of the address mapping:
TOOSHORT - The received frame is shorter than
802.3 minimum size (64 bytes on the cable).
ADDRESS
ED 00 00 00 00 00
0D 00 00 00 00 00
01 00 00 00 00 00
2F 00 00 00 00 00
HASH VALUE 5-0
000 000
010 000
100 111
111 111
MULTCAST - Receive frame was multicast. If hash
value corresponds to a multicast table bit that is
set, and the address was a multicast, the
MULTICAST TABLE BIT
MT-0 bit 0
MT-2 bit 0
MT-4 bit 7
MT-7 bit 7
packet will pass address filtering regardless of
other filtering criteria.
31
structure is similar for ISA and PCMCIA modes
with the following exceptions:
INTERRUPT STRUCTURE
The LAN91C95 merges two main interrupt sources
into a single interrupt line. One source is the
Ethernet interrupt and the other is the modem
interrupt. The Ethernet interrupt is conceptually
equivalent to the LAN91C92 interrupt line; it is the
OR function of all enabled interrupts within the
Ethernet core. The modem interrupt is an input pin
(MINT). The enabling, reporting and clearing of
these two sources is controlled by the ECOR,
ECSR, MCOR and MCSR registers. The interrupt
a)
PCMCIA uses a single interrupt pin (nIREQ)
while ISA can use any of four INTR0-INTR3
pins.
b)
PCMCIA defaults to Ethernet interrupts
disabled (Enable IREQ=0 in ECOR), while ISA
defaults to Ethernet interrupts enabled.
The following table summarizes the interrupt
merging:
TABLE 4 - LAN91C95 INTERRUPT MERGING
FUNCTION
PCMCIA MODE
ISA MODE
INTR0-INTR3
Interrupt Output
nIREQ when either function is
enabled. When both functions are
disabled the nIREQ is used to report
the latched value of MRDY.
Ethernet Interrupt Source
OR function of all interrupt bits specified in the Interrupt Status Register
ANDed with their respective Enable bits.
Modem Interrupt Source
MINT input pin.
Ethernet Interrupt Enable
Enable IREQ bit in ECOR. This bit
defaults low in PCMCIA mode.
Modem Interrupt Enable
Enable IREQ bit in MCOR. This bit defaults low.
Ethernet Interrupt Status
Bit
Intr bit in ECSR.
Modem Interrupt Status
Bit
Intr bit in MCSR.
32
Enable IREQ bit in ECOR. This
bit defaults high in ISA mode.
RESET LOGIC
POR -
The pins and bits involved in the different reset
mechanisms are:
nMRESET SRESET -
RESET -
Input Pin
SOFT RST -
Internal circuit activated by Power
On
Output pin to reset modem
Soft Reset bit in ECOR and
MCOR, one SRESET bit for each
function.
EPH Soft Reset bit in RCR
TABLE 5 - RESET FUNCTIONS
RESETS THE
FOLLOWING FUNCTIONS
ACTIVATES
SAMPLES ISA
VS. PCMCIA
MODE
TRIGGERS
EEPROM
READ
nMRESET
Yes
Yes
RESET Pin
All internal logic
POR Circuit
Generates an internal reset of at least 15 msec, with same effect as the RESET pin
ECOR
Register
SRESET Bit
The Ethernet controller
function
and
Ethernet
PCMCIA
Configuration
Registers except for the bit
itself
No
No
MCOR
Register
SRESET Bit
The
Modem
controller
function
and
Modem
PCMCIA
Configuration
Registers except for the bit
itself
No
No
SOFT RST
The Ethernet Controller itself
except for the IA, CONF,
and BASE registers. It does
not reset any PCMCIA
Configuration Register
No
No
33
POWERDOWN LOGIC
The pins and bits involved in powerdown are:
1.
2.
3.
4.
5.
6.
PWRDWN/TXCLK - Input pin valid when XENDEC is not zero (0).
Pwrdwn bits in ECSR and MCSR registers - One bit for each function
Enable Function bits in ECOR and MCOR registers - One bit for each function
PWRDN - Ethernet powerdown bit in Control Register.
WAKUP_EN - Magic packet receive enable bit in the Control Register
nWAKEUP - Pin for Magic Packet receive + Ethernet function powerdown
Table 6A - ISA MODE Defined States (Refer to table 6B for next states to wake-up events)
(*Rev. C and Higher)
CURRENT STATE
No.
1
PWRD
WN
Pin(A=
Assrtd)
A
nWAKE
UP-EN
PIN
(A=
Assrtd)
X
ECOR
FUCNTION
ENABLE
X
ECSR
POWER
DOWN
X
CTR
PWRD
WN BIT
X
CTR
WAKEUP_EN
BIT
X
MCOR
FUNC
ENABLE
X
MCSR
POWER
DOWN
X
2
nA
A
X
X
X
X
-
-
3
nA
nA
X
0
0
0
-
-
4
nA
nA
X
0
0
0
1
1
-
-
Ethernet
Tx
5
nA
nA
X
0
1
0
-
-
Ethernet
Tx, Rx,
Link
POWERS
DOWN
Everything.
Asserts the
modem
power
down pin
(nPWDN)
also
Note 1: The chart assumes that ECOR Function Enable bit is meaningless in ISA mode.
Note 2: ECSR Power Down bit must not be set to one(1) in ISA mode
34
Ethernet
Tx
DOES
NOT
POWER
DOWN
Ethernet
Rx, Link
Ethernet
Tx, Rx,
Link
Ethernet
Rx, Link
Table 6B - ISA MODE (*Rev. C and Higher)
NEXT STATE
WAKES
UP BY
PWRDWN
Pin
deassertn
nWAKEUP
-EN Pin
deassertn AND-,
ECSR
PWRDWN
= 0, CTR
PWRDWN
bit = 0
PWR DWN
Pin
(A=Assrtd)
nA
nWAKEUPECOR
EN PIN
FUCNTIO
(A=Assrtd) N ENABLE
X
No change
ECSR
POWER
DOWN
No
change
CTR
PWRDWN BIT
No
change
CTR
WAKE
UP_EN
BIT
No
change
MCOR
FUNC
ENABLE
No
change
MCSR
POWER
DOWN
No
change
nA
nA
No change
0
0
No
change
-
-
nA
nA
X
0
0
0
-
-
Note 1: The chart assumes that ECOR Function Enable bit is meaningless in ISA mode.
Note 2: ECSR Power Down bit must not be set to one (1) in ISA mode
35
COMMENTS
ECOR
Function
Enable Bit
value is
meaningless
in ISA mode
Fully Awake
Table 7A - PCMCIA MODE (Refer to table 7B for next states to wake-up events)
(*Rev. C and Higher)
CURRENT STATE
No.
1
PWRD
WN
Pin(A=A
ssrtd)
A
nWAKE
UP-EN
PIN
(A=Assr
td)
X
ECOR
FUNC
ENABLE
X
ECSR
PWR
DOWN
X
CTR
PWR
DWN
BIT
X
CTR
WAKE
UP_E
N BIT
X
MCOR
FUNC
ENABLE
X
MCSR
PWR
DOWN
X
2
nA
A
X
X
X
X
-
-
3
nA
nA
1
0
0
0
-
-
4
nA
nA
1
0
0
1
-
-
Ethernet Tx
Ethernet Rx,
Link; PCMCIA
Att/Config Mem
5
nA
nA
0
X
X
0
-
-
Ethernet Tx,
Rx, Link
PCMCIA Att/Conf
Memory
6
nA
nA
0
1
0
1
0
1
1
1
-
-
Ethernet Tx
Ethernet Rx,
Link; PCMCIA
Att/Conf Memory
7
nA
nA
0
X
X
1
1
-
-
Ethernet Tx
Ethernet Rx,
Link; PCMCIA
Att/Conf Memory
8
nA
nA
1
1
0
0
-
-
Ethernet Tx,
Rx, Link
PCMCIA
Att/Config Mem
8S
nA
nA
1
1
1
0
-
-
Ethernet Tx,
Rx, Link
PCMCIA
Att/Config Mem
9
nA
nA
1
1
0
1
-
-
Ethernet Tx
Ethernet Rx,
Link; PCMCIA
Att/Config Mem
9S
nA
nA
1
1
1
1
-
-
Ethernet Tx
Ethernet Rx,
Link; PCMCIA
Att/Config Mem
POWERS
DOWN
Everything.
Asserts the
modem
power down
pin(nPWDN)
also
DOES NOT
POWER DOWN
Ethernet Tx
Ethernet Rx,
Link; PCMCIA
Att/Config Mem
Ethernet Tx, Rx,
Link; PCMCIA
Att/Config Mem
Note1: Implementation is such that the IREQ signal is not generated for a Magic Packet detect
while the function is disabled.
36
Table 7B - PCMCIA MODE (*Rev. C and Higher)
NEXT STATE
PWR
DWN
Pin
(A=Ass
rtd)
nA
nWAKE
UP-EN
PIN
(A=Ass
rtd)
X
nWAKEUPEN Pin
deassertn AND- ECOR
Func. En. = 1,
ECSR
PWRDWN =
0, CTR
PWRDWN bit
=0
nA
nA
nA
nA
1
0
0
0
-
-
Fully Awake
By writing a 0
to CTR
WAKEUP_EN
bit
nA
nA
1
0
0
0
-
-
MP
precedence
nA
nA
0
X
X
0
-
-
By writing 1
to 0 to ECSR
Power Down,
a 0 to CTR
PWRDWN,
and a 0 to
WAKEUP_EN
bit
nA
nA
1
0
0
0
-
-
NOTE: Both
Power down
bits need to
be written as
0 only if both
were set to 1
By writing 1 to
ECOR Func
Enable, 0 to
ECSR Power
Down, 0 to
CTR
PWRDWN,
and 0 to
WAKEUP_EN
bit
nA
nA
1
0
0
0
-
-
NOTE: Both
Power down
bits need to
be written as
0 only if both
were set to 1
By writing 0 to
ECSR Power
Down bit*
nA
nA
1
0
0
0
-
-
By writing 0 to
ECSR Power
Down and a 0
to CTR
PWRDWNbit
nA
nA
1
0
0
0
-
-
WAKES UP
BY
PWRDWN
Pin deassertn
ECOR
FUNC
ENABLE
No
change
ECSR
PWR
DOWN
No
change
CTR
PWRDWN
BIT
No change
No
change
No
change
No change
37
CTR
WAKE
UP_EN
BIT
No
change
No
change
MCOR
FUNC
ENABLE
No
change
MCSR
PWR
DOWN
No
change
-
-
COMMENTS
Pin
deassertion
will make the
Att/Conf Mem
accessible
entirely
NOTE: Both
Power down
bits need to
be written as
0 only if both
were set to 1
NEXT STATE
WAKES UP
BY
By writing 0 to
ECSR Power
Down taking
the chip out of
MP mode by
writing
WAKEUP_EN
=0
By writing 0 to
ECSR Power
Down, a 0 to
CTR
PWRDWN,
and a 0 to
WAKEUP_EN
bit
PWR
DWN
Pin
(A=Ass
rtd)
nA
nWAKE
UP-EN
PIN
(A=Ass
rtd)
nA
ECOR
FUNC
ENABLE
1
ECSR
PWR
DOWN
0
CTR
PWRDWN
BIT
0
CTR
WAKE
UP_EN
BIT
0
MCOR
FUNC
ENABLE
-
MCSR
PWR
DOWN
-
nA
nA
1
0
0
0
-
-
38
COMMENTS
Table 8A - Effect of STSCHG_SLCT Bit in CR/Refer to table 8B for next states to wake-up
events
(*Rev. C and Higher)
CURRENT STATE
No
MCOR
FUNC
ENABLE
BIT
MCSR
PWR
DOWN
BIT
CR
STSCHG_
SLCT BIT
(New)
MODEM IN
POWER DOWN
Ring Event (Assuming
Enabled) on nSTSCHG
Pin (A=Assrtd)
Ring Event (Assuming
Disabled) on nSTSCHG Pin
(A=Assrtd)
1
0
X
0
Y
nA
nA
2
0
X
1
Y
A
nA
3
1
0
X
N
A
nA
4
1
1
X
Y
A
nA
Table 8B (*Rev. C and Higher)
NEXT STATE
MCOR
FUNCTION
ENABLE BIT
MCSR
POWER
DOWN BIT
CR STSCHG_SLCT
BIT (New)
MODEM IN
POWER
DOWN
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
No Change
39
The LAN91C95 generates the appropriate control
lines (nFCS and nFWE) to read and write the
Attribute memory, and it tri-states the data bus
during external Attribute Memory accesses. Note
that the parallel EEPROM is selected for the first
512 byte CIS information also in the absence of the
serial EEPROM in PCMCIA mode. Only even
locations are used.
PCMCIA Attribute Memory: Address 07FFEh
The Attribute Memory is implemented using a
combination of interrnal SRAM and external
parallel EEPROM, ROM or Flash ROM. The
internal SRAM is initialized during power up using
the serial EEPROM. This serial EEPROM in
PCMCIA mode is used for the CIS (Card
Information Structure). If no serial EEPROM is
used, the parallel EEPROM must be used. Internal
CIS RAM address space is replaced by part of the
external parallel EEPROM in this case.
Internal VS External Attribute Memory Map
The Internal VS External EPROM attribute memory
decodes are shown below. This allows the designer
to not require an external EPROM device if the
single or multi-function PCMCIA card needs less
than 512 bytes of configuration information. As can
be seen in the map, if 512 bytes of CIS or less is
required, the nFCS and nFWE output pins of the
LAN91C95 need not be
used (if serial EEPROM is being used). Internal to
the LAN91C95, the memory addressing logic will
allow byte or word on odd byte address access
(A0=1), the LAN91C95 will generate an arbitrary
value of zero (0) since the PCMCIA specification
states that the high byte of a word access in
attribute memory is a don’t care. This allows
backward compatibility to 8 bit hosts.
In ISA mode, the serial EEPROM is used for
configuration and IEEE Node address making it
software compatible to the LAN9000 family of
Ethernet LAN Controllers. In ISA mode, the
EEPROM is optional requiring a minimum size of
64 X 16 bit word addresses. In PCMCIA mode, the
minimum serial EEPROM (if used) size can be 64
X 16 up to 256 X 16.
This combination of internal and external attribute
memory allows the designer to reduce costs by
using a serial EEPROM device when using up to
512 bytes of “Card Information” and, if additional
memory is needed, an external EEPROM may be
used. When the LAN91C95 goes into powerdown
mode, the internal CIS data buffer RAM is reinitialized.
40
TABLE 9 - ATTRIBUTE MEMORY ADDRESS USING SERIAL EEPROM
ATTRIBUTE
MEMORYADDRESS
EXTERNAL EPROM
STORE
0 - 3FEh
400h-7FFEh
INTERNAL SRAM
STORE (512 BYTES)
CONFIGURATION
REGISTERS
X
X
8000h - 803Eh
X
TABLE 10 - ATTRIBUTE MEMORY ADDRESS WITHOUT SERIAL EEPROM
ATTRIBUTE
MEMORYADDRESS
EXTERNAL EPROM
STORE
0 - 7FFEh
X
8000h - 803Eh
INTERNAL SRAM
STORE (512 BYTES)
CONFIGURATION
REGISTERS
X
These registers are eight bits wide and reside on
even locations. The LAN91C95 ignores odd
accesses to this area (ignore writes, do not drive
the bus on reads). This address offset has been
changed from prior LAN9000 PCMCIA designs
to allow a larger address range for other
attribute memory data. This data could be a
larger card information structure or a XIP data
image.
PCMCIA Configuration Registers: Address
8000-803Eh
The PCMCIA Configuration Registers are stored
inside the LAN91C95 above the external Attribute
Memory address space. These registers are used
to configure and control the PCMCIA related
functionality of the Ethernet and Modem functions.
41
PCMCIA CONFIGURATION REGISTERS DESCRIPTION
Ethernet Function (Base Address 8000h)
8000h - Ethernet Configuration Option Register (ECOR)
7
6
SRESET
LevIREQ
0
1
5
0
4
3
0
2
1
0
WRATTRIB
Enable
IREQ
Enable
Base and
Limit
Enable
Function
0
0
0
0
board decoder is used to select the function. If
cleared, the decoder is disabled and it is
assumed that the host provides for the
decoding. When the decode is disabled, the
function is enabled, and is configured for 16 bits
(and not in power-down mode), the signal
nIOIS16 is always asserted. It is then up to the
host to qualify the usage of nIOIS16. For
multifunction PCMCIA functionality, this bit
must be set.
BIT 7 - SRESET: This bit when set will clear all
internal registers associated with the Ethernet
function except itself.
BIT 6 - LevIREQ: This bit is read only and reads
as a one to indicate level mode interrupts are
used. Pulse mode interrupts are not supported.
BIT 5 - Not defined
BIT 4 - Not defined
BIT 0 - Enable Function: This bit enables (1) or
disables (0) the Ethernet function. While the
Ethernet function is disabled it remains in
powerdown mode, no access to the Ethernet I/O
space is allowed. (ie. The bank register is not
accessable). IREQ is not generated for this
function and nINPACK is not returned for
accesses to the Ethernet registers.
BIT 3 - WRATTRIB: This bit when when set (1),
allows writting into the external attribute memory
space.
BIT 2 - Enable IREQ Routing: This bit enables
(1) or disables (0) the Ethernet function from
asserting nIREQ. The nIREQ pin on power up
and RESET is in a high (1) de-asserted state.
If the “Magic Packet” function is enabled, the
device is not completley powered down. The
MAC controller is still enabled to receive.
BIT 1 - Enable Base and Limit: This bit enables
the on board I/O base decoder. If set, the on-
42
8002h - Ethernet Configuration and Status Register (ECSR)
7
6
5
4
3
IOIs8
0
0
0
0
0
2
1
0
Pwrdwn
Intr
IntrACK
0
0
0
When this bit and Enable IREQ Routing are set,
IREQ Out is asserted.
BIT 7 - Not defined
BIT 6 - Not defined
All setting and resetting of this bit is edge
triggered with exception of the internally
generated reset signal for the modem Ethernet
related PC card registers. The Intr bit can be
reset the following ways and priority ranging
from 1=highest to 3=lowest:
BIT 5 - IOIs8: This bit when set, indicates that
the Host can only do 8 bit cycles (on D7-D0).
The Ethernet function is forced in this case to
eight bit mode regardless of the nEN16 pin and
16 BIT value. This bit also disables (floats) the IOIs16 signal.
1)
2)
BIT 4 - Not defined
BIT 3 - Not defined
3)
BIT 2 - PwrDwn: When set (1), this bit puts the
LAN91C95 Ethernet function into powerdown
mode. The Ethernet function is also put into
powerdown mode when the Enable Function bit
(ECOR bit 0) is cleared. Refer to the Powerdown
Logic section for additional details as to what
logic is powered down.
A hardware reset/power up
The function ie. interrupt source can only
reset this field to zero (0) if the IntrACK field
is reset to zero (0)
The host system can only reset this field to
a zero (0) if the IntrACK bit is set to a one
(1)
BIT 0 - IntrACK: This bit controls the clearing of
the Intr bit. When this bit is cleared, Intr reflects
the function's interrupt status. When this bit is
set, the Intr bit must be cleared by the host
writing a 0 into it. If the function requires
additional service the Intr bit will remain
asserted when the host writes the 0.
BIT 1 - Intr: This bit is read/set to a one when
this function is requesting interrupt service. It is
cleared depending upon the setting of IntrACK.
43
I/O Base Register 0 & 1 (I/O Base 0 & 1) Address 800Ah & 800Ch
800Ah - Ethernet I/O BASE Register 0
7
6
5
4
3
2
1
0
A7
A6
A5
A4
0
0
0
0
0
0
0
0
0
0
0
0
800Ch - Ethernet I/O BASE Register 1
7
6
5
4
3
2
1
0
A15
A14
A13
A12
A11
A10
A9
A8
0
0
0
0
0
0
1
1
Only A15 to A4 are decoded by the controller
(64K address space), it is up to the host to
resolve any conflicts with addressing above
64K. The default decode value is 300h
(A9=A8=1, others=0). NOTE: These registers
are ignored in ISA mode. These registers are
accessable even if the “Enable Base and Limit)
bit in the MCOR is cleared (0).
The I/O Base registers determine the base
address of the I/O range used to access function
specific registers. These registers allow the
function's registers to be placed anywhere in the
host's I/O space. I/O Base 0 contains the low
order byte (A7-A0) and I/O Base 1 contains the
high order byte (A15-A8). Since the Ethernet
function requires 16 I/O locations, bits 3-0 of I/O
Base 0 are always 0.
44
Modem Function (Base Address 8020h)
8020h - Modem Configuration Option Register (MCOR)
7
6
SRESET
LevIREQ
0
1
5
0
4
3
0
0
2
1
0
Enable
IREQ
Enable
Base and
Limit
Enable
Function
0
0
0
BIT 1 - Enable Base and Limit: This bit enables
the on board modem I/O base decoder. If set,
the on-board decoder is used to select the
function. If cleared, the decoder is disabled and
it is assumed that the host provides for the
decoding. When the decode is disabled, the
function is enabled, and is configured for 16 bits
(and not in power-down mode), the signal
nIOIS16 is always asserted.
For
multifunction PCMCIA functionality, this bit
must be set.
BIT 7 - SRESET: This bit when set clears all
internal registers associated with the Modem
function (except itself) and asserts the
nMRESET pin .
BIT 6 - LevIREQ: This bit is read only and reads
as a one to indicate level mode interrupts are
used. Pulse mode interrupts are not supported.
BIT 5 - Not defined
BIT 4 - Not defined
BIT 0 - Enable Function: This bit enables (1) or
disables (0) the Modem function. While the
Modem is disabled the LAN91C95 inhibits
nMCS, IREQ is not generated for the Modem
function and nINPACK is not returned for
accesses to the Modem registers.
BIT 3 - Not defined
BIT 2 - Enable IREQ Routing: This bit enables
(1) or disables (0) the Modem function from
asserting nIREQ.
45
8022h - Modem Configuration and Status Register (MCSR) Address 8022h
7
6
5
4
3
2
1
0
Changed
SigChg
IOIs8
Reserved
Audio
Pwrdwn
Intr
IntrACK
0
0
0
0
0
0
0
0
the modem is awakened by a pulse on the
output ringing signals as appropriate. The pulse
duration is determined by the input signal
MRINGIN. MRINGIN is then passed to the
outputs.
Bit 7 - Changed: This bit is the logical OR of the
CREADY/-Bsy and (RINGEVENT bit logically
anded with RINGENABLE) states.
Bit 6 - SigChg: If this bit is a one, the function is
enabled (configured), the Changed bit controls
the nSTSCHG pin. If this bit is low or the
function is disabled, the nSTSCHG pin is set to
a high.
Bit 1 - Intr: This bit is read/set to a one when
this function is requesting interrupt service. It is
cleared depending upon the setting of IntrACK.
When this bit and Enable IREQ Routing are set,
-IREQOut is asserted.
Bit 5 - IOIs8: This bit when set, indicates that
the Host can only do 8 bit cycles (on D7-D0). In
the case of the IOIs8 bit being cleared (0),
during Reset and Power up for example, the PIN
MIS16 will override the IOIs8 default, setting
the bit (1).
The Intr bit can be reset the following ways and
priority ranging from 1=highest to 3=lowest:
1)
2)
A hardware reset/power up
The function ie. interrupt source can only
reset this field to zero (0) if the IntrACK field
is reset to zero (0)
The host system can only reset this field to
a zero (0) if the IntrACK bit is set to a one
(1)
Bit 4 - ResurvedBit 3 - Audio: This bit controls
the audio pass through of the digital audio.
When cleared, the SPKROUT pin is
three-stated. When set, the SPKRIN pin is
passed to the SPKROUT pin.
3)
Bit 2 - PwrDwn: When set (1), this bit puts the
modem into powerdown mode. The modem is
also put into powerdown mode when the Enable
Function bit is cleared. When in powerdown,
the MRINGIN signal is blocked from going to the
ringing output signal.
When taken out of
powerdown (when PwrDwn is cleared (1) and
Enable Function in the MCOR (bit 0) is set (1)),
Bit 0 - IntrACK: This bit controls the clearing of
the Intr bit. When this bit is cleared, Intr reflects
the function's interrupt status. When this bit is
set, the Intr bit must be cleared by the host
writing a 0 into it. If the function requires
additional service (indicated by leaving MINT
active) the Intr bit will remain asserted when the
host writes the 0.
46
8024h - Pin Replacement Register (PRR)
7
6
5
4
3
2
Cready/
-Bsy
0
0
0
0
Rready/
-Bsy
0
0
0
1
0
value for Rready/Bsy bit. A CPU write to this bit
is successful only if the Rready/-Bsy bit is being
written as one (1). Note that the h/w represented
value of the Rready/-Bsy bit itself is not affected
by the write attempt as shown in the following
illustration:
Cready/-Bsy: This bit is set to a one when the
bit Rready/-Bsy bit changes state from zero(0)
to one (1) or one (1) to zero (0) with the source
of the change of state is a change in the modem
ready (MRDY) signal. The Cready/-Bsy bit can
be written by the CPU also. The CPU attempt to
write to this bit is masked by the
CURRENT VALUE
1
VALUE WRITTEN
NEW VALUE
Cready/-Bsy
Rready/-Bsy
Cready/-Bsy
Rready/-Bsy
Cready/-Bsy
Rready/-Bsy
0
0
1
0
0
0
X
0
1
1
1
0
X
0
0
1
0
0
X
1
1
1
1
1
In the unlikely event that the MRDY changes
state at the same time that the nWE signal
changes from low to high (ie. writing the
register), the value written by the host will have
priority over the new state of the MRDY input
pin.
Rready/-Bsy: When read, this bit represents the
current state of the modem Ready/-Busy
(MRDY) signal. Attempts of CPU writes to this
bit are ignored.
47
8028h - Extended Status Register(ESR)
7
6
5
4
3
2
1
RINGEVENT
0
0
0
0
0
RINGENABLE
0
0
0
0
host writes a one (1) and the change bit in the
MCSR register is unaffected if the host writes a
zero (0).
RINGEVENT: This bit is latched to a one at the
start of each ring frequency cycle (input from
ring input from modem, the MRINGIN signal
going high). When this bit and RINGENABLE
are both set to a one (1), the Changed bit in the
MCSR is set to a one(1). This bit is reset if the
RINGENABLE: When set, this bit gates the
RINGEVENT into the Changed bit.
48
802Ah - Modem I/O BASE Register 0
7
6
5
4
3
2
1
0
A7
A6
A5
A4
A3
0
0
0
0
0
0
0
0
0
0
0
802Ch - Modem I/O BASE Register 1
7
6
5
4
3
2
1
0
A15
A14
A13
A12
A11
A10
A9
A8
0
0
0
0
0
0
1
1
Base 0 are always 0. Since only A15 to A4 are
decoded by the controller (64K address space),
it is up to the host to resolve any conflicts with
addressing above 64K.
The Modem I/O Base registers determine the
base address of the I/O range used to access
function specific registers. These registers allow
the function's registers to be placed anywhere in
the host's I/O space. I/O Base 0 contains the
low order byte (A7-A0) and I/O Base 1 contains
the high order byte (A15-A8). Since the modem
function requires 8 I/O locations, bits 2-0 of I/O
These registers are still accessable even if the
“Enable Base and Limit” bit in the MCOR is
cleared (0).
49
8032h - Modem I/O Size Register
Modem I/O Size Mask
0
0
0
0
0
1
1
1
state the data bus during Modem I/O space
accesses. In ISA mode, nMCS is disabled (1). No
address decodeing for the modem will be done.
The I/O Size Register holds a bit mask used to
specify the number of address lines decoded by the
Modem function. Each bit in the register represents
an I/O address line. A value of one means that the
LAN91C95 will not decode the corresponding
address line for the Modem function, a value of
zero means that the address line will be decoded. If
a bit in the register is set to one, all bits of lesser
significance in the register must also be set to one.
Ethernet I/O Space: Address determined by
Ethernet I/O Base Registers
The Ethernet I/O space consists of sixteen
locations whose base address is determined in
PCMCIA mode by the Ethernet I/O Base Registers,
and in ISA mode by the default value of the Base
Register (either reset or serial EEPROM default in
ISA mode only).
This register defaults to 7h, that is A0, A1 and A2
are not decoded resulting in 8 address locations for
the modem function.
The Ethernet I/O space can be configured as an 8
or 16 bit space, and is similar to the LAN91C95,
LAN91C92, etc. I/O space. To limit the I/O space
requirements to 16 locations, the registers are split
into six banks. The last word of the I/O area is
shared by all banks and can be used to change the
bank in use. Banks 0 through 3 functionally
correspond to the LAN91C95 banks, while Banks 4
and 5 allow access to the multifunction registers in
ISA mode.
Modem I/O Space: Address determined by
Modem I/O Base Registers
The Modem I/O space is external to the
LAN91C95. The LAN91C95 decodes the address
bus ( A15 through A3) via a internal comparator
and generates nMCS for I/O cycles that decode to
the Modem area as defined by the Modem I/O
Base Registers. The I/O address space consists of
eight (8) 8 bit locations. The LAN91C95 will tri-
50
I/O SPACE
(ISA and PCMCIA Mode)
To limit the I/O space requirements to 16 locations,
the registers are assigned to different banks. The
last word of the I/O area is shared by all banks and
can be used to change the bank in use.
In ISA mode, the base I/O space is determined by
the IOS0-IOS2 inputs and the EEPROM contents.
A4-A15 are compared against the base I/O
address for I/O space accesses.
Registers are described using the following
convention:
In PCMCIA mode nREG (along with nIORD or
nIOWR) defines an I/O access regardless of the
A4-A15 value.
OFFSET
HIGH
BYTE
LOW
BYTE
NAME
TYPE
SYMBOL
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
X
X
X
X
X
X
X
X
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
X
X
X
X
X
X
X
X
OFFSET - Defines the address offset within the
IOBASE where the register can be accessed at,
provided the bank select has the appropriate value.
Some registers (like the Interrupt Ack., or like
Interrupt Mask) are functionally described as two
eight bit registers; in that case the offset of each
one is independently specified.
The offset specifies the address of the even byte
(bits 0-7) or the address of the complete word.
Regardless of the functional description, when the
LAN91C95 is in 16 bit mode, all registers can be
accessed as words or bytes.
The odd byte can be accessed using address
(offset + 1).
The default bit values upon hard reset are
highlighted below each register.
51
TABLE 11 Internal I/O Space Map
BANK0
BANK1
BANK2
BANK3
BANK4
BANK5
0
TCR
CONFIG
MMU
COMMAND
MT0-MT1
ECOR
(low byte)
ECSR
(high byte)
MCOR
(low byte)
MCSR
(high byte)
2
EPH STATUS
BASE
PNR ARR
MT2-MT3
4
RCR
IA0-IA1
FIFO PORTS
MT4-MT5
EBASE0
(high byte)
IOEIR
(low byte)
MBASE0
(high byte)
6
COUNTER
IA2-IA3
POINTER
MT6-MT7
EBASE1
(low byte)
MBASE1
(low byte)
8
MIR
IA4-IA5
DATA
MGMT
A
MCR
GENERAL
PURPOSE
DATA
REVISION
C
RESERVED
(0)
CONTROL
INTERRUPT
ERCV
E
BANK
SELECT
BANK
SELECT
BANK
SELECT
BANK
SELECT
52
PRR
(low byte)
Msize
(high byte)
BANK SELECT REGISTER
I/O REGISTERS DESCRIPTION
OFFSET
NAME
BANK SELECT
REGISTER
E
HIGH
BYTE
LOW
BYTE
TYPE
SYMBOL
READ/WRITE
BSR
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Res.
Res.
Res.
Res.
Res.
BS2
BS1
BS0
X
X
X
X
X
0
0
0
BS2, BS1, BS0 - Determine the bank presently in
use.
The BANK SELECT REGISTER is always
accessible regardless of the value of BS0-BS2.
The BANK SELECT REGISTER is always
accessible except in PCMCIA powerdown mode
and is used to select the register bank in use.
The LAN91C95 implements only four banks in ISA
mode, therefore, accesses to non-existing banks
(BS2=1) are ignored. All six banks are accessible
in PCMCIA mode.
The upper byte always reads as 33h and can be
used to help determine the I/O location of the
LAN91C95.
BS2
0
0
0
0
1
BS1
0
0
1
1
X
BS0
0
1
0
1
X
53
BANK#
0
1
2
3
None
I/O SPACE - BANK0
OFFSET
NAME
TRANSMIT CONTROL
REGISTER
0
TYPE
SYMBOL
READ/WRITE
TCR
This register holds bits programmed by the CPU to control some of the protocol transmit options.
HIGH
BYTE
LOW
BYTE
FDSE
0
Res
X
EPH
LOOP
0
STP
SQET
0
FDUPLX
0
MON_
CSN
0
Res
X
NOCRC
0
PAD_EN
0
Res
X
Res
X
Res
X
Res
X
FORCOL
0
LOOP
0
TXENA
0
FDSE - Full Duplex Switched Ethernet. When set,
the LAN91C95 is configured for Full Duplex
Switched Ethernet, it defaults clear to normal
CSMA/CD protocol. In FDSE mode the LAN91C95
transmit and receive processes are fully
independent, namely no deferral and no collision
detection are implemented. When FDSE is set,
FDUPLX is internally assumed high and
MON_CSN is assumed low regardless of their
actual values.
a frame sourced by itself. Clearing this bit (Normal
Operation) in promiscuous mode allows it to not
receive its own packet.
MON_CSN - When set, the LAN91C95 monitors
carrier while transmitting. It must see its own
carrier by the end of the preamble. If it is not seen,
or if carrier is lost during transmission, the
transmitter aborts the frame without CRC and turns
itself off. When this bit is clear the transmitter
ignores its own carrier. Defaults low.
EPH_LOOP - Internal loopback at the EPH block.
Does not exercise the encoder decoder. Serial data
is looped back when set. Defaults low.
NOCRC - Does not append CRC to transmitted
frames when set; allows software to insert the
desired CRC. Defaults to zero, namely CRC
inserted.
NOTE: After exiting the loopback test, an
SRESET in the ECOR or the SOFT_RST in the
RCR must be set before returning to normal
operation.
PAD_EN - When set, the LAN91C95 will pad
transmit frames shorter than 64 bytes with 00.
Does not pad frames when reset.
STP_SQET - Stop transmission on SQET error. If
set, stops and disables transmitter on SQE test
error. Does not stop on SQET error and transmits
next frame if clear. Defaults low.
FORCOL - When set, the transmitter will force a
collision by deliberately not deferring. After the
collision, this bit is automatically reset. This bit
defaults low for normal operation. Note: The
LATCOL bit in EPHSR, setting up as a result of
FORCOL, will reset TXENA to 0. In order to force
another collision, TXENA must be set to 1 again.
FDUPLX
- When set, it enables full duplex
operation. This will cause frames to be received if
they pass the address filter regardless of the source
for the frame. When clear the node will not receive
54
LOOP - Local Loopback. When set, transmit
frames are internally looped to the receiver after the
encoder/decoder. Collision and Carrier Sense are
ignored. No data is sent out. Defaults low for
normal mode.
TXENA - Transmit enabled when set. Transmit is
disabled if clear. When the bit is cleared, the
LAN91C95 will complete the current transmission
before stopping. When stopping due to an error,
this bit is automatically cleared.
TRANSMITS
AUI
FDSE
FDUPLX
EPH_LOOP
LOOP
LOOPS AT
TO
NETWORK
X
X
X
1
X
EPH Block
No
X
X
1
0
1
ENDEC
No
1
0
1
0
0
Cable
Yes
0
0
1
0
0
10BASE-T Driver
Yes
X
0
0
0
0
Normal CSMA/CD - No
Loopback
Yes
X
1
1
0
0
Full Duplex Switched
Ethernet - No loopback
and no SQET
Yes
55
I/O SPACE - BANK0
OFFSET
2
NAME
EPH STATUS REGISTER
TYPE
READ ONLY
SYMBOL
EPHSR
This register stores the status of the last transmitted frame. This register value, upon individual transmit
packet completion, is stored as the first word in the memory area allocated to the packet. Packet interrupt
processing should use the copy in memory as the register itself will be updated by subsequent packet
transmissions. The register can be used for real time values (like TXENA and LINK OK). If TXENA is cleared
the register holds the last packet completion status.
HIGH
BYTE
LOW
BYTE
TX
UNRN
LINK_
OK
RX_
OVRN
CTR
_ROL
EXC
_DEF
LOST
CARR
LATCOL
WAKEUP
0
0
0
0
0
0
0
0
TX
DEFR
LTX
BRD
SQET
16COL
LTX
MULT
MUL
COL
SNGL
COL
TX_SUC
0
0
0
0
0
0
0
0
TXUNRN - Transmit Underrun. Set if underrun
occurs, it also clears TXENA bit in TCR. Cleared by
setting TXENA high. This bit may only be set if
early TX is being used.
EXC_DEF - Excessive deferral. When set
last/current transmit was deferred for more than
1518 * 2 byte times. Cleared at the end of every
packet sent.
LINK_OK - State of the 10BASE-T Link Integrity
Test. A transition on the value of this bit generates
an interrupt when the LE ENABLE bit in the Control
Register is set.
LOST_CARR - Lost carrier sense. When set
indicates that Carrier Sense was not present at end
of preamble. Valid only if MON_CSN is enabled.
This condition causes TXENA bit in TCR to be
reset. Cleared by setting TXENA bit in TCR.
RX_OVRN - Upon FIFO overrun, the receiver
asserts this bit and clears the FIFO. The receiver
stays enabled. After a valid preamble has been
detected on a subsequent frame, RX_OVRN is deasserted. The RX_OVRN INT bit in the Interrupt
Status Register will also be set and stay set until
cleared by the CPU. Note that receive overruns
could occur only if receive memory allocations fail.
LATCOL - Late collision detected on last transmit
frame. If set a late collision was detected (later than
64 byte times into the frame). When detected the
transmitter jams and turns itself off clearing the
TXENA bit in TCR. Cleared by setting TXENA in
TCR.
WAKEUP - When this bit is set, it indicates that a
receive packet was received that had the “Magic
Packet” (MP) signature of the node’s own IP
address repetitions in it. This bit indicates a valid
CTR_ROL - Counter Roll over. When set one or
more 4 bit counters have reached maximum count
(15). Cleared by reading the ECR register.
56
detection for magic packet - enabled by
nWAKEUPEN pin (92 QFP) or WAKEUP_EN in
CTR.
bit in TCR is reset. Cleared when TXENA is set
high.
LTX_MULT - Last transmit frame was a multicast.
Set if frame was a multicast. Cleared at the start of
every transmit frame.
Note: If the MP mode is activated using the
nWAKEUPEN pin, the pin must be deasserted to
exit the mode.
MULCOL - Multiple collision detected for the last
transmit frame. Set when more than one collision
was experienced. Cleared when TX_SUC is high at
the end of the packet being sent.
TX_DEFR - Transmit Deferred. When set, carrier
was detected during the first 6.4 µsec of the inter
frame gap. Cleared at the end of every packet sent.
LTX_BRD - Last transmit frame was a broadcast.
Set if frame was broadcast. Cleared at the start of
every transmit frame.
SNGLCOL - Single collision detected for the last
transmit frame. Set when a collision is detected.
Cleared when TX_SUC is high at the end of the
packet being sent.
SQET - Signal Quality Error Test. The transmitter
opens a 1.6 µsec window 0.8 µsec after
transmission is completed and the receiver returns
inactive. During this window, the transmitter
expects to see the SQET signal from the
transceiver. The absence of this signal is a 'Signal
Quality Error' and is reported in this status bit.
Transmission stops and EPH INT is set if
STP_SQET is in the TCR is also set when SQET is
set. This bit is cleared by setting TXENA high.
TX_SUC - Last transmit was successful. Set if
transmit completes without a fatal error. This bit is
cleared by the start of a new frame transmission or
when TXENA is set high.
Fatal errors are:
16 collisions
SQET fail and STP_SQET = 1
FIFO Underrun
Carrier lost and MON_CSN = 1
Late collision
16COL- 16 collisions reached. Set when 16
collisions are detected for a transmit frame. TXENA
57
I/O SPACE - BANK0
OFFSET
4
HIGH
BYTE
LOW
BYTE
NAME
RECEIVE CONTROL REGISTER
TYPE
READ/WRITE
SYMBOL
RCR
SOFT_
RST
FILT_
CAR
Res
Res
Res
Res
STRIP_
CRC
RXEN
0
0
0
0
0
0
0
0
Res
Res
Res
Res
Res
ALMUL
PRMS
RX_
ABORT
0
0
0
0
0
0
0
0
SOFT_RST - Software activated Reset. Active
high. Initiated by writing this bit high and terminated
by writing the bit low. The LAN91C95 configuration
is not preserved, except for Configuration, Base,
and IA0-IA5 Registers. The EEPROM in both ISA
and PCMCIA mode is not reloaded after software
reset.
RXEN - Enables the receiver when set. If cleared,
completes receiving current frame and then goes
idle. Defaults low on reset.
ALMUL - When set accepts all multicast frames
(frames in which the first bit of DA is '1'). When
clear accepts only the multicast frames that match
the multicast table setting. Defaults low.
FILT_CAR - Filter Carrier. When set filters leading
edge of carrier sense for 12 bit times. Otherwise
recognizes a receive frame as soon as carrier
sense is active.
PRMS - Promiscuous mode. When set receives all
frames. Does not receive its own transmission
unless it is in full duplex.
STRIP_CRC - When set it strips the CRC on
received frames. When clear the CRC is stored in
memory following the packet. Defaults low.
RX_ABORT - This bit is set if a receive frame is
aborted due to length longer than 1532 bytes. The
frame will not be received. The bit is cleared by
RESET or by the CPU writing it low.
RX_ABORT
RX_OVRN_INT
Packet Too Long
1
0
Run out of Memory
During Receive
1
1
58
I/O SPACE - BANK0
OFFSET
6
NAME
COUNTER REGISTER
TYPE
READ ONLY
SYMBOL
ECR
Counts four parameters for MAC statistics. When any counter reaches 15 an interrupt is issued. All counters
are cleared when reading the register and do not wrap around beyond 15.
HIGH
BYTE
NUMBER OF EXC. DEFFERED TX
0
LOW
BYTE
0
0
0
NUMBER OF DEFFERED TX
0
MULTIPLE COLLISION COUNT
0
0
0
0
0
0
SINGLE COLLISION COUNT
0
Each four bit counter is incremented every time the
corresponding event, as defined in the EPH
STATUS REGISTER bit description, occurs. Note
that the counters can only increment once per
enqueued transmit packet, never faster, limiting the
rate of interrupts that can be generated by the
counters. For example if a packet is successfully
transmitted after one collision the SINGLE
COLLISION COUNT field is incremented by one. If
a packet experiences between 2 to 16 collisions,
the MULTIPLE COLLISION COUNT field is
incremented by one. If a packet experiences
0
0
0
0
deferral the NUMBER OF DEFERRED TX field is
incremented by one, even if the packet experienced
multiple deferrals during its collision retries.
The COUNTER REGISTER facilitates maintaining
statistics in the AUTO RELEASE mode where no
transmit interrupts are generated on successful
transmissions.
Reading the register in the transmit service routine
will be enough to maintain statistics.
59
I/O SPACE - BANK0
OFFSET
8
NAME
MEMORY INFORMATION REGISTER
HIGH
BYTE
TYPE
READ ONLY
SYMBOL
MIR
FREE MEMORY AVAILABLE (IN BYTES * 256 * M)
0
0
LOW
BYTE
0
1
1
0
0
0
0
0
MEMORY SIZE (IN BYTES *256 * M)
0
0
0
1
FREE MEMORY AVAILABLE - This register can be
read at any time to determine the amount of free
memory. The register defaults to the MEMORY
SIZE upon reset or upon the RESET MMU
command.
1
0
MEMORY SIZE - This register can be read to
determine the total memory size, and will always
read 18H (6144 bytes) for the LAN91C95.
MEMORY SIZE REGISTER
M
ACTUAL MEMORY
LAN91C90
FFH
1
64 kbytes
LAN91C90
40H
1
16 kbytes
LAN91C92/4
12H
1
4608 bytes
LAN91C95
18H
1
6144 bytes
LAN91C100
FFH
2
128 kbytes
60
I/O SPACE - BANK0
OFFSET
NAME
A
MEMORY CONFIGURATION REGISTER
HIGH
BYTE
TYPE
Lower Byte READ/WRITE
Upper Byte - READ
ONLY
SYMBOL
MCR
MEMORY SIZE MULTIPLIER
0
LOW
BYTE
0
1
1
0
0
1
1
MEMORY RESERVED FOR TRANSMIT (IN BYTES * 256 * M)
0
0
0
0
MEMORY RESERVED FOR TRANSMIT Programming this value allows the host CPU to
reserve memory to be used later for transmit,
limiting the amount of memory that receive packets
can use up.
0
0
0
0
The value written to the MCR is a reserved memory
space IN ADDITION TO ANY MEMORY
CURRENTLY IN USE. If the memory allocated for
transmit plus the reserved space for transmit is
required to be constant (rather than grow with
transmit allocations) the CPU should update the
value of this register after allocating or releasing
memory.
When programmed for zero, the memory allocation
between transmit and receive is completely
dynamic.
The contents of MIR as well as the low byte of
MCR are specified in 256 * M bytes. The multiplier
M is determined by bits 11,10, and 9 as follows.
Bits 11,10 and 9 are read only bits used by the
software driver to transparently run on different
controllers of the LAN9000 family.
When programmed for a non-zero value, the
allocation is dynamic if the free memory exceeds
the programmed value, while receive allocation
requests are denied if the free memory is less or
equal to the programmed value.
This register defaults to zero upon reset. It is not
affected by the RESET MMU command.
DEVICE
BIT 11
BIT 10
BIT 9
M
MAX MEMORY SIZE
FEAST
0
1
0
2
256*256*2=128k
LAN91C90
0
0
1
1
256*256*1=64k
FUTURE
0
1
1
4
256k
FUTURE
1
0
0
8
512k
FUTURE
1
0
1
16
1M
61
I/O SPACE - BANK1
OFFSET
0
NAME
CONFIGURATION REGISTER
TYPE
READ/WRITE
SYMBOL
CR
The Configuration Register holds bits that define the device configuration and are not expected to change
during run-time. This register is part of the EEPROM saved setup in ISA mode only. In PCMCIA mode, this
register is initialized to the state as defined below the corresponding bits as if no EEPROM was present in
ISA mode (i.e. ENEEP pin is a don’t care in PCMCIA mode).
HIGH
BYTE
LOW
BYTE
0
0
X
16 BIT
DIS
LINK
Function
of EN16
pin
0
X
NO
WAIT
STSCHG
_SLCT
FULL
STEP
SET
SQLCH
AUI
SELECT
0
0
0
0
0
INT SEL1
INT SEL0
0
0
Reserved
1
1
0
NO WAIT - When set, does not request additional
wait states. An exception to this are accesses to the
Data Register if not ready for a transfer. When
clear, negates IOCHRDY for two to three 20 MHz
clocks on any cycle to the LAN91C95.
X
FULL STEP - This bit is used to select the signaling
mode for the AUI port. When set the AUI port uses
full step signaling. Defaults low to half step
signaling. This bit is only meaningful when AUI
SELECT is high.
STSCHG_SLCT(*) - PCMCIA mode only. With
STSCHG_SLCT low (0), Modem Function Enable
bit = 0, in MCOR, it does not allow any events
(such as Ring In) to be reported to the host via the
nSTSCHG Pin assertion. With STSCHG_SLCT
high (1), Functon Enable = 0, and does not prohibit
any events (such as Ring In) to be reported to the
host via the nSTSCHG Pin assertion. Look for
further event enabling and individual enable bits
(such as RINGENABLE in the MESR) information
in the PCMCIA Registers description.
SET SQLCH - When set, the squelch level used for
the 10BASE-T receive signal is 240mV. When
clear the receive squelch level is 400mV. Defaults
low.
AUI SELECT - When set the AUI interface is used,
when clear the 10BASE-T interface is used.
Defaults low.
16 BIT - Used in conjunction with nEN16 and IOis8
(in PCMCIA mode only) to define the width of the
system bus. If the nEN16 pin is low, this bit is
forced high. Otherwise the bit defaults low and can
be programmed by the host CPU.
Note *: Rev. C or higher
Note: SRESET bit in MCOR, SRESET bit in
ECOR, or SOFT_RST bit in RCR assertion have no
effect on the STSCHG_SLCT bit. POR or chip
reset with the RESET pin will reset the bit to zero
(0).
DIS LINK - This bit is used to disable the 10BASET link test functions. When this bit is high the
62
LINK_OK bit will be low, while transmit packets
enqueued will be processed by the LAN91C95,
transmit data will not be sent out to the cable.
LAN91C95 disables link test functions by not
generating nor monitoring the network for link
pulses. In this mode the LAN91C95 will transmit
packets regardless of the link test, the EPHSR
LINK_OK bit will be set and the LINK LED will stay
on. When low the link test functions are enabled. If
the link status indicates FAIL, the EPHSR
INT SEL1-0 - In ISA mode, used to select one out
of four interrupt pins. The three unused interrupts
are tristated.
INT SEL1
INT SEL0
INTERRUPT PIN USED
0
0
1
1
0
1
0
1
INTR0
INTR1
INTR2
INTR3
63
I/O SPACE - BANK1
OFFSET
2
NAME
BASE ADDRESS REGISTER
TYPE
READ/WRITE
SYMBOL
BAR
For ISA mode only, this register holds the I/O address decode option chosen for the I/O and ROM space. It
is part of the EEPROM saved setup, and is not usually modified during run-time. NOTE: This register
should ONLY be used in ISA mode. In PCMCIA mode, this register is read only.
HIGH
BYTE
LOW
BYTE
A15
A14
A13
A9
A8
A7
A6
A5
0
0
0
1
1
0
0
0
RA18
RA17
RA16
RA15
RA14
1
0
0
1
1
ROM SIZE
0
1
A15 - A13 and A9 - A5 - These bits are compared
in ISA mode against the I/O address on the bus to
determine the IOBASE for LAN91C95 registers.
The 64k I/O space is fully decoded by the
LAN91C95 down to a 16 location space, therefore
the unspecified address lines A4, A10, A11 and
A12 must be all zeros.
1
only memory accesses defined by nMEMRD going
low.
For a full decode of the address space unspecified
upper address lines have to be:
A19 = "1", A20-A23 lines are not directly
decoded, however ISA systems will only
activate nMEMRD only when A20-A23=0.
ROM SIZE - Determines the ROM decode area in
ISA mode memory space as follows:
All bits in this register are loaded from the serial
EEPROM in ISA Mode only. In PCMCIA mode, the
I/O base is set to the default value (as in ISA
mode) as defined below.
00 = ROM disable
01 = 16k: RA14-18 define ROM select
10 = 32k: RA15-18 define ROM select
11 = 64k: RA16-18 define ROM select
The I/O base decode defaults to 300h (namely, the
high byte defaults to 18h). ROM SIZE defaults to
01. ROM decode defaults to CC000 (namely the
low byte defaults to 67h).
RA18-RA14 - These bits are compared in ISA
mode against the memory address on the bus to
determine if the ROM is being accessed, as a
function of the ROM SIZE. ROM accesses are read
64
I/O SPACE - BANK1
OFFSET
4 THROUGH 9
NAME
INDIVIDUAL ADDRESS REGISTERS
These registers are loaded starting at word location
20h of the EEPROM upon hardware reset or
EEPROM reload in ISA mode only. The registers
can be modified by the software driver, but a
STORE operation will not modify (in ISA mode
only) the EEPROM Individual Address contents.
SYMBOL
IAR
The LAN91C95 in PCMCIA mode knows nothing
about the location or structure of the IEEE Ethernet
Address stored in the EEPROM. Once this data is
stored in the CIS SRAM data buffer in the
LAN91C95, it is parsed by the host to extract the
IEEE Address information and stored manualy by
the LAN Driver.
In PCMCIA mode, the IEEE Individual Address is
stored in the EEPROM, but is stored in PCMCIA
Tuple format as defined in the Metaformat
specification. Refer to the PCMCIA v3.0 card
specification on the Metaformat.
HIGH
BYTE
TYPE
READ/WRITE
Bit 0 of Individual Address 0 register corresponds
to the first bit of the address on the cable.
ADDRESS 0
0
0
0
LOW
BYTE
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ADDRESS 1
0
0
0
HIGH
BYTE
0
0
ADDRESS 2
0
0
0
LOW
BYTE
0
0
ADDRESS 3
0
0
0
HIGH
BYTE
0
0
ADDRESS 4
0
0
0
LOW
BYTE
0
0
ADDRESS 5
0
0
0
0
65
0
I/O SPACE - BANK1
OFFSET
A
NAME
GENERAL PURPOSE REGISTER
HIGH
BYTE
TYPE
READ/WRITE
SYMBOL
GPR
HIGH DATA BYTE
0
0
0
LOW
BYTE
0
0
0
0
0
0
0
0
LOW DATA BYTE
0
0
0
0
This register can be used as a way of storing and
retrieving non-volatile information in the EEPROM
to be used by the software driver. The storage is
word oriented, and the EEPROM word address to
be read or written is specified using the six lowest
bits of the Pointer Register. In PCMCIA mode, Bits
0 to 10 of the pointer register are used.
0
This register can also be used to sequentially
program the Individual Address area of the
EEPROM, that is normally protected from
accidental Store operations.
This register will be used for EEPROM read and
write only when the EEPROM SELECT bit in the
Control Register is set. This allows generic
EEPROM read and write routines that do not affect
the basic setup of the LAN91C95.
66
I/O SPACE - BANK1
OFFSET
C
HIGH
BYTE
LOW
BYTE
NAME
CONTROL REGISTER
TYPE
READ/WRITE
0
RCV_
BAD
PWRDWN
WAKE
UP_EN
AUTO
RELEASE
0
0
0
0
0
LE
ENABLE
CR
ENABLE
TE
ENABLE
0
0
0
X
RCV_BAD - When set, bad CRC packets are
received. When clear bad CRC packets do not
generate interrupts and their memory is released.
X
SYMBOL
CTR
1
X
X
1
EEPROM
SELECT
RELOAD
STORE
0
0
0
AUTO RELEASE - When set, transmit pages are
released by transmit completion if the transmission
was successful (when TX_SUC is set). In that case
there is no status word associated with its packet
number, and successful packet numbers are not
even written into the TX COMPLETION FIFO. A
sequence of transmit packets will only generate an
interrupt when the sequence is completely
transmitted (TX EMPTY INT will be set), or when a
packet in the sequence experiences a fatal error
(TX INT will be set).
PWRDN - Active high bit used to put the Ethernet
function in powerdown mode.
Cleared by:
1. A write to any register in the LAN91C95 I/O
space
2. Hardware reset
3. “Magic Packet” was received
Upon a fatal error TXENA is cleared and the
transmission sequence stops. The packet number
that failed is the present in the FIFO PORTS
register, and its pages are not released, allowing
the CPU to restart the sequence after corrective
action is taken.
This bit is combined with the Pwrdwn bit in ECSR
and with the powerdown bit to determine when the
function is powered down.
WAKUP_EN - Active high bit used to enable the
controller in any of the powerdown modes to power
up if a “Magic Packet” is detected and set the
WAKEUP bit in the EPHSR to generate an EPH
interrupt (if not masked). When clear (0), no
“Magic Packet” scanning is done on receive
packets.
LE ENABLE - Link Error Enable. When set it
enables the LINK_OK bit transition as one of the
interrupts merged into the EPH INT bit. Defaults
low (disabled). Writing this bit also serves as the
acknowledge by clearing previous LINK interrupt
conditions.
NOTE:
If “Magic Packet” is enabled using this
bit only the notification is done on the WAKEUP bit
in the EPHSR only.
CR ENABLE - Counter Roll over Enable. When set
it enables the CTR_ROL bit as one of the interrupts
merged into the EPH INT bit. Defaults low
(disabled).
67
TE ENABLE - Transmit Error Enable. When set it
enables Transmit Error as one of the interrupts
merged into the EPH INT bit. Defaults low
(disabled). Transmit Error is any condition that
clears TXENA with TX_SUC staying low as
described in the EPHSR register.
STORE
In ISA Mode: The STORE bit when set, stores
the contents of all relevant registers in the serial
EEPROM. This bit is cleard upon completing
the operation.
In PCMCIA Mode: The LAN91C95 performs no
function.
EEPROM SELECT - This bit allows the CPU to
specify which registers the EEPROM RELOAD or
STORE refers to. When high, the General Purpose
Register is the only register read or written. When
low, the RELOAD and STORE functions are
enabled.
NOTE: When an EEPROM access is in progress
the STORE and RELOAD bits will be read back as
high. The remaining 14 bits of this register will be
invalid. During this time, attempted read/write
operations, other than polling the EEPROM status,
will NOT have any effect on the internal registers.
The CPU can resume accesses to the LAN91C95
after both bits are low. A worst case RELOAD
operation initiated by RESET or by software takes
less than 750 µsec.
RELOAD
In ISA Mode:
The LAN91C95 reads the
Configuration, Base and Individual Address,
and STORE writes the Configuration and Base
registers. Also when set it will read the
EEPROM and update relevant registers with its
contents. This bit then Clears upon completing
the operation.
PCMCIA EEPROM to SRAM Memory Map
As defined in the PCMCIA specification, Odd byte
attribute memory locations are a don’t care. In
order to utilize the serial EEPROM and internal
LAN91C95 SRAM, the data to memory mapping is
shown in Table 12.
In PCMCIA Mode: The LAN91C95 reads the
contents of the EEPROM and stores the contents
in the LAN91C95 CIS SRAM as defined in Table
12.
68
ATTRIBUTE MEMORY
HOST ADDRESS (HEX)
000
001
002
003
004
005
006
..
3F8
3F9
3FA
3FB
3FC
3FD
3FE
3FF
Table 12 PCMCIA - EEPROM to SRAM Memory Map
ATTRIBUTE
EEPROM ADDRESS
DATA
IN WORDS
Data Byte 0
Word 1 - Low Byte
Don’t Care
Data Byte 1
Word 1 - High Byte
Don’t Care
Data Byte 2
Word 2 - Low Byte
Don’t Care
Data Byte 3
Word 2 - High Byte
..
..
Data Byte 1FC
Word FE - Low Byte
Don’t Care
Data Byte 1FD
Word FE- High Byte
Don’t Care
Data Byte 1FE
Word FF - Low Byte
Don’t Care
Data Byte 1FF
Word FF - High Byte
Don’t Care
Note: This memory map assumes a 4096 bit Serial EEPROM in PCMCIA mode.
69
LAN91C95 SRAM
IN BYTES
Byte 0
Byte1
Byte2
Byte3
..
Byte FC
Byte1FD
Byte1FE
Byte1FF
I/O SPACE - BANK2
OFFSET
NAME
0
MMU COMMAND REGISTER
TYPE
WRITE ONLY
BUSY Bit Readable
SYMBOL
MMUCR
This register is used by the CPU to control the memory allocation, de-allocation, TX FIFO and RX FIFO
control. The three command bits determine the command issued as described below:
HIGH
BYTE
LOW
BYTE
COMMAND
x
y
0
0
N2
N1
N0/BUSY
z
0
COMMAND SET:
xyz
000
0)
NOOP - NO OPERATION
001
1)
ALLOCATE MEMORY FOR TX - N2,N1,N0 defines the amount of memory requested as (value
+ 1) * 256 bytes. Namely N2,N1,N0 = 1 will request 2 * 256 = 512 bytes. Valid range for
N2,N1,N0 is 0 through 5. A shift-based divide by 256 of the packet length yields the appropriate
value to be used as N2,N1,N0. Immediately generates a completion code at the ALLOCATION
RESULT REGISTER. Can optionally generate an interrupt on successful completion. The
allocation time can take worst case (N2, N1, N0 + 2) * 200ns.
010
2)
RESET MMU TO INITIAL STATE - Frees all memory allocations, clears relevant interrupts,
resets packet FIFO pointers.
011
3)
REMOVE FRAME FROM TOP OF RX FIFO - To be issued after CPU has completed
processing of present receive frame. This command removes the receive packet number from
the RX FIFO and brings the next receive frame (if any) to the RX area (output of RX FIFO).
100
4)
REMOVE AND RELEASE TOP OF RX FIFO - Like 3) but also releases all memory used by
the packet presently at the RX FIFO output.
101
5)
RELEASE SPECIFIC PACKET - Frees all pages allocated to the packet specified in the
PACKET NUMBER REGISTER. Should not be used for frames pending transmission.
Typically used to remove transmitted frames, after reading their completion status. Can be
used following 3) to release receive packet memory in a more flexible way than 4).
70
110
6)
ENQUEUE PACKET NUMBER INTO TX FIFO - This is the normal method of transmitting a
packet just loaded into RAM. The packet number to be enqueued is taken from the PACKET
NUMBER REGISTER.
111
7)
RESET TX FIFOs - This command will reset both TX FIFOs: the TX FIFO holding the packet
numbers awaiting transmission and the TX Completion FIFO. This command provides a
mechanism for canceling packet transmissions, and reordering or bypassing the transmit
queue. The RESET TX FIFOs command should only be used when the transmitter is disabled.
Unlike the RESET MMU command, the RESET TX FIFOs does not release any memory.
Note 1: Only command 1) uses N2,N1,N0.
Note 2: When using the RESET TX FIFOS command, the CPU is responsible for releasing the memory
associated with outstanding packets, or re-enqueuing them. Packet numbers in the completion FIFO can be
read via the FIFO ports register before issuing the command.
Note 3: MMU commands releasing memory (commands 4 and 5) should only be issued if the corresponding
packet number has memory allocated to it.
COMMAND SEQUENCING
command 5, the contents of the PNR should not be
changed until BUSY goes low. After issuing
command 4, command 3 should not be issued until
BUSY goes low.
A second allocate command (command 1) should
not be issued until the present one has completed.
Completion is determined by reading the FAILED
bit of the allocation result register or through the
allocation interrupt.
BUSY BIT - Readable at bit 0 of the MMU
command register address. When set indicates
that MMU is still processing a release command.
When clear, MMU has already completed last
release command. BUSY and FAILED bits are set
upon the trailing edge of command.
A second release command (commands 4, 5)
should not be issued if the previous one is still
being processed. The BUSY bit indicates that a
release command is in progress. After issuing
71
I/O SPACE - BANK2
OFFSET
2
NAME
PACKET NUMBER REGISTER
TYPE
READ/WRITE
SYMBOL
PNR
PACKET NUMBER AT TX AREA
0
0
0
0
0
PACKET NUMBER AT TX AREA - The value
written into this register determines which packet
number is accessible through the TX area. Some
MMU commands use the number stored in this
OFFSET
3
0
0
0
register as the packet number parameter. This
register is cleared by a RESET or a RESET MMU
Command.
NAME
ALLOCATION RESULT REGISTER
TYPE
READ ONLY
SYMBOL
ARR
This register is updated upon an ALLOCATE MEMORY MMU command.
FAILED
1
ALLOCATED PACKET NUMBER
0
0
0
0
0
0
ALLOCATED PACKET NUMBER - Packet number
associated with the last memory allocation
request. The value is only valid if the FAILED bit is
clear.
FAILED - A zero indicates a successful allocation
completion. If the allocation fails the bit is set and
only cleared when the pending allocation is
satisfied. Defaults high upon reset and reset MMU
command. For polling purposes, the ALLOC_INT
in the Interrupt Status Register should be used
because it is synchronized to the read operation.
Sequence:
1)
2)
3)
0
Note:
For software compatibility with future
versions, the value read from the ARR after an
allocation request is intended to be written into the
PNR as is, without masking higher bits (provided
FAILED = 0).
Allocate Command
Poll ALLOC_INT bit until set
Read Allocation Result Register
72
I/O SPACE - BANK2
OFFSET
4
NAME
FIFO PORTS REGISTER
TYPE
READ ONLY
SYMBOL
FIFO
This register provides access to the read ports of the Receive FIFO and the Transmit completion FIFO. The
packet numbers to be processed by the interrupt service routines are read from this register.
HIGH
BYTE
REMPTY
1
LOW
BYTE
RX FIFO PACKET NUMBER
0
0
0
TEMPTY
1
0
0
0
0
TX DONE PACKET NUMBER
0
0
0
REMPTY - No receive packets queued in the RX
FIFO. For polling purposes, uses the RCV_INT bit
in the Interrupt Status Register.
0
0
0
0
TX DONE PACKET NUMBER - Packet number
presently at the output of the TX Completion FIFO.
Only valid if TEMPTY is clear. The packet is
removed when a TX INT acknowledge is issued.
TOP OF RX FIFO PACKET NUMBER - Packet
number presently at the output of the RX FIFO.
Only valid if REMPTY is clear. The packet is
removed from the RX FIFO using MMU
Commands 3) or 4).
NOTE: For software compatibility with future
versions, the value read from each FIFO register is
intended to be written into the PNR as is, without
masking higher bits (provided TEMPTY and
REMPTY = 0 respectively).
TEMPTY - No transmit packets in completion
queue. For polling purposes, uses the TX_INT bit in
the Interrupt Status Register.
73
I/O SPACE - BANK2
OFFSET
6
HIGH
BYTE
NAME
POINTER REGISTER
TYPE
READ/WRITE
RCV
AUTO
INCR.
READ
ETEN
0
0
0
0
0
0
LOW
BYTE
SYMBOL
PTR
POINTER HIGH
0
0
0
0
0
0
POINTER LOW
0
0
0
0
0
POINTER REGISTER - The value of this register
determines the address to be accessed within the
transmit or receive areas. It will auto-increment on
accesses to the data register when AUTO INCR. is
set. The increment is by one for every byte access,
and by two for every word access.
The Pointer Register should not be loaded until
400ns after the last write operation to the Data
Register to ensure that the Data Register FIFO is
empty. If the pointer is loaded using 8 bit writes, the
low byte should be loaded first and the high byte
last.
RCV - When RCV is set the address refers to the
receive area and uses the output of RX FIFO as the
packet number, when RCV is clear the address
refers to the transmit area and uses the packet
number at the Packet Number Register.
ETEN bit - When set enables EARLY Transmit
underrun detection. Normal operation when clear.
For Underrun detection purposes the RAM logical
address and packet numbers of the packet being
loaded are compared against the logical address
and packet numbers of the packet being
transmitted. If the packet numbers match and the
logical address of the packet being transmitted
exceeds the address being loaded the packet
transmission is aborted and Underrun is reported in
the transmit status word.
READ - Determines the type of access to
follow. If the READ bit is high the operation
intended is a read. If the READ bit is low the
operation is a write. Loading a new pointer value,
with the READ bit high, generates a pre-fetch into
the Data Register for read purposes.
NOTE: If AUTO INCR. is not set and 16 bits are
used, the pointer must be loaded with an even
value. If AUTO INCR. is not set and 8 bit (allows
even and odd values) writes are used, consecutive
writes to the data register for the same pointer
(same memory address) value is not allowed; even
and odd pointer values are always allowed.
Readback of the pointer will indicate the value of
the address last accessed by the CPU (rather than
the last pre-fetched). This allows any interrupt
routine that uses the pointer, to save it and restore
it without affecting the process being interrupted.
74
I/O SPACE - BANK2
OFFSET
8 THROUGH Ah
NAME
DATA REGISTER
TYPE
READ/WRITE
SYMBOL
DATA
DATA HIGH
DATA LOW
DATA REGISTER - Used to read or write the data
buffer byte/word presently addressed by the pointer
register.
order to and from the FIFO is preserved. Byte and
word accesses can be mixed on the fly in any
order.
This register is mapped into two uni-directional
FIFOs that allow moving words to and from the
LAN91C95 regardless of whether the pointer
address is even or odd. Data goes through the
write FIFO into memory, and is pre-fetched from
memory into the read FIFO. If byte accesses are
used, the appropriate (next) byte can be accessed
through the Data Low or Data High registers. The
This register is mapped into two consecutive word
locations to facilitate the usage of double word
move instructions. The DATA register is accessible
at any address in the 8 through Ah range, while the
number of bytes being transferred are determined
by A0 and nSBHE in ISA mode, and by A0, nCE1
and nCE2 in PCMCIA mode.
75
I/O SPACE - BANK2
OFFSET
C
NAME
INTERRUPT STATUS REGISTER
TYPE
READ ONLY
SYMBOL
IST
Res.
ERCV INT
EPH INT
RX_OVR
N INT
ALLOC
INT
TX
EMPTY
INT
TX INT
RCV INT
X
0
0
0
0
1
0
0
OFFSET
C
Res.
NAME
INTERRUPT ACKNOWLEDGE REGISTER
ERCV INT
OFFSET
D
Res.
RX_OVR
N INT
Res.
NAME
INTERRUPT MASK REGISTER
TYPE
WRITE ONLY
TX EMPTY
INT
SYMBOL
ACK
TX INT
TYPE
READ/WRITE
Res.
SYMBOL
MSK
Res.
ERCV INT
EPH INT
RX_OVR
N INT
ALLOC
INT
TX
EMPTY
INT
TX INT
RCV INT
X
0
0
0
0
0
0
0
This register can be read and written as a word or
as two individual bytes.
LINK_OK transition
CTR_ROL - Statistics counter roll over.
TXENA cleared - A fatal transmit error occurred
forcing TXENA to be cleared. TX_SUC will be low
and the specific reason will be reflected by the bits:
TXUNRN - Transmit underrun
SQET - SQE Error
LOST CARR - Lost Carrier
LATCOL - Late Collision
16COL - 16 collisions
WAKE_UP - “Magic Packet” is received if
enabled
RX_OVRN INT - Set when the receiver overruns
due to a failed memory allocation. The RX_OVRN
bit of the EPHSR will also be set, but if a new
The Interrupt Mask Register bits enable the
appropriate bits when high and disable them when
low. An enabled bit being set will cause a hardware
interrupt.
EPH INT - Set when the Ethernet Protocol Handler
section indicates one out of various possible
special conditions. This bit merges exception type
of interrupt sources, whose service time is not
critical to the execution speed of the low level
drivers. The exact nature of the interrupt can be
obtained from the EPH Status Register (EPHSR),
and enabling of these sources can be done via the
Control Register. The possible sources are:
76
packet is received it will be cleared. The RX_OVRN
INT bit, however, latches the overrun condition for
the purpose of being polled or generating an
interrupt, and will only be cleared by writing the
acknowledge register with the RX_OVRN INT bit
set.
register. The TX INT bit is always the logic
complement of the TEMPTY bit in the FIFO
PORTS register. After servicing a packet number,
its TX INT interrupt is removed by writing the
Interrupt Acknowledge Register with the TX INT bit
set.
ALLOC INT - Set when an MMU request for TX
pages allocation is completed. This bit is the
complement of the FAILED bit in the ALLOCATION
RESULT register. The ALLOC INT ENABLE bit
should only be set following an allocation
command, and cleared upon servicing the
interrupt.
RCV INT - Set when a receive interrupt is
generated. The first packet number to be serviced
can be read from the FIFO PORTS register. The
RCV INT bit is always the logic complement of the
REMPTY bit in the FIFO PORTS register.
ERCV INT - Early receive interrupt. Set whenever a
receive packet is being received, and the number of
bytes received into memory exceeds the value
programmed as ERCV THRESHOLD (Bank 3,
Offset Ch).
ERCV INT stays set until
acknowledged by writing the INTERRUPT
ACKNOWLEDGE REGISTER with the ERCV INT
bit set.
TX EMPTY INT - Set if the TX FIFO goes empty,
can be used to generate a single interrupt at the
end of a sequence of packets enqueued for
transmission. This bit latches the empty condition,
and the bit will stay set until it is specifically cleared
by writing the acknowledge register with the TX
EMPTY INT bit set. If a real time reading of the
FIFO empty is desired, the bit should be first
cleared and then read. The TX EMPTY INT
ENABLE should only be set after the following
steps:
a)
b)
NOTE: If the driver uses AUTO RELEASE mode it
should enable TX EMPTY INT as well as TX INT.
TX EMPTY INT will be set when the complete
sequence of packets is transmitted. TX INT will be
set if the sequence stops due to a fatal error on any
of the packets in the sequence.
a packet is enqueued for transmission
the previous empty condition is cleared
(acknowledged)
NOTE: For edge triggered systems, the Interrupt
Service Routine should clear the Interrupt Mask
Register, and only enable the appropriate interrupts
after
the
interrupt
source
is
serviced
(acknowledged).
TX INT - Set when at least one packet transmission
was completed. The first packet number to be
serviced can be read from the FIFO PORTS
77
D4
78
FIGURE 9 - INTERRUPT STRUCTURE
FAILED
OE
BUS
nRDIST
5
MERGED INTO EPH INT
nQ
S Q
DATA
D
4
3
2
1
16
D0-7
D8-15
REGISTER
4
REGISTER
5
MASK
0
STATUS
1
INTERRUPT
2
INTERRUPT
3
TX COMPLETION FIFO
NOT EMPTY
EPHSR INTERRUPTS
TX_SVC
TXENA
TEMASK
CRMASK
CTR-ROL
LEMASK
ON LINK ERR
nQ
S Q
ALLOCATION
D
RX_OVRN (EPHSR)
EDGE DETECTOR
nWRACK
D2
TX
FIFO EMPTY
RCV FIFO
nOE
0
NOT EMPTY
MAIN INTERRUPTS
EPH INT
RX_OVRN
INT
ALLOC
INT
EMPTY
INT
TX
TX INT
RCV INT
INT
I/O SPACE - BANK 3
OFFSET
0 THROUGH 7
NAME
MULTICAST TABLE
LOW
BYTE
TYPE
READ/WRITE
SYMBOL
MT
MULTICAST TABLE 0
0
0
0
HIGH
BYTE
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
MULTICAST TABLE 1
0
0
0
LOW
BYTE
0
0
MULTICAST TABLE 2
0
0
0
HIGH
BYTE
0
0
MULTICAST TABLE 3
0
0
0
LOW
BYTE
0
0
MULTICAST TABLE 4
0
0
0
HIGH
BYTE
0
0
MULTICAST TABLE 5
0
0
0
LOW
BYTE
0
0
MULTICAST TABLE 6
0
0
0
HIGH
BYTE
0
0
MULTICAST TABLE 7
0
0
0
0
The 64 bit multicast table is used for group address
filtering. The hash value is defined as the six most
significant bits of the CRC of the destination
addresses. The three msb's determine the register
to be used (MT0-MT7), while the other three
determine the bit within the register.
If the
appropriate bit in the table is set, the packet is
received. If the ALMUL bit in the RCR register is
set, all multicast addresses are received regardless
of the multicast table values.
0
Hashing is only a partial group addressing filtering
scheme, but being the hash value available as part
of the receive status word, the receive routine can
reduce the search time significantly. With the
proper memory structure, the search is limited to
comparing only the multicast addresses that have
the actual hash value in question.
79
I/O SPACE - BANK3
OFFSET
8
NAME
MANAGEMENT INTERFACE
TYPE
READ/WRITE
HIGH
BYTE
0
0
1
0
nXNDEC
IOS2
IOS1
IOS0
MDOE
MCLK
MDI
MDO
0
0
0
0
1
LOW
BYTE
0
SYMBOL
MGMT
1
1
nXNDEC - Read only bit reflecting the status of the
nXENDEC pin.
MDI - Reads the value of the EEDI pin.
MDCLK - The value of this bit drives the EESK pin
when MDOE=1.
IOS0-IOS2 - Read only bits reflecting the status of
the IOS0-IOS2 pins.
MDOE - When this bit is high pins EEDO EECS
and EESK will be used for transceiver
management functions, otherwise the pins assume
the EEPROM values.
MDO - The value of this bit drives the EEDO pin
when MDOE=1.
MDOE = 0
MDOE = 1
EEDO
Serial EEPROM Data Out
Bit MDO
EESK
Serial EEPROM Clock
Bit MCLK
EECS
Serial EEPROM Chip Select
0
80
I/O SPACE - BANK3
OFFSET
A
NAME
REVISION REGISTER
TYPE
READ ONLY
SYMBOL
REV
HIGH
BYTE
0
0
LOW
BYTE
1
1
0
0
CHIP
0
1
1
1
0
0
REV
0
0
CHIP - Chip ID. Can be used by software drivers to
identify the device used.
0
0
REV - Revision ID. Incremented for each revision
of a given device.
CHIP ID VALUE
DEVICE
3
LAN91C90/LAN91C92
4
LAN91C94
5
LAN91C95
7
FEAST
81
I/O SPACE - BANK 3
OFFSET
C
NAME
EARLY RCV REGISTER
TYPE
READ/WRITE
SYMBOL
ERCV
HIGH
BYTE
0
LOW
BYTE
0
1
1
0
RCV
DISCRD
0
0
1
1
1
1
ERCV THRESHOLD
0
0
1
RCV DISCRD - Set to discard a packet being
received. This bit can be used in conjunction with
ERCV THRESHOLD and ERCV INT to process a
packet header while it is being received and sicard
it if the packet is not desired. Setting this bit will
only discard packets that are still in the process of
being received.
1
1
being set, the packet is received normally and RCV
INT bit is set in the Interrupt Status Register. The
RCV DISCRD bit is self-clearing.
ERCV THRESHOLD - Threshold for ERCV
interrupt. Specified in 64 byte multiples. Whenever
the number of bytes written in memory for the
presently received packet exceeds the ERCV
THRESHOLD, ERCV INT bit of the INTERRUPT
STATUS REGISTER is set.
If the RCV DISCRD bit is set prior to the end of a
receive packet, RXOVRN bit in the Interrupt Status
Register will be set to indicate that the packet was
discarded and its memory released. If the receive
packet is complete prior to the RCV DISCRD bit
Refer to the PCMCIA Configuration Registers
Description for Banks 4 and 5.
82
THEORY OF OPERATION
it does not want a specific part of the packet, a
block move operation starting at any particular
offset can be done. Out of order receive
processing is also supported: if memory for one
packet is not yet available, receive packet
processing can continue.
PC Card 5.0 treats the individual functions of a
multifunction
PCMCIA
application
independently.
Card and Socket Services
(C&SS) 5.0 is designed to provide the support
for determining the function generating the
interrupt and informing relevant drivers. The
registers for the two functions are treated as
independent sets. One of the only requirements
is to set the functions’ I/O base registers with
different values to avoid any access conflict.
Efficiency - Lacking any level of indirection or
linked lists of pointers, virtually all the memory
is used for data. There are no descriptors,
forward links and pointers at all. This simplicity
and memory efficiency is accomplished without
giving up the benefits of linked lists which is
unlimited back-to-back transmission and
reception without CPU intervention for as long
as memory is available.
MEMORY ARCHITECTURE
The concept of presenting the shared RAM as
FIFO of packets, with a memory management
unit allocating memory on a per packet basis
responds to the following needs:
FULL DUPLEX ETHERNET SUPPORT
Memory allocation for receive vs. transmit - A
fixed partition between receive and transmit area
would not be efficient.
Being able to
dynamically allocate it to transmit and receive
represents almost the equivalent of duplicating
the memory size for some workstation type of
drivers.
Full Duplex Ethernet operation refers to the
ability of the network (or parts of it) to
simultaneously transmit and receive packets.
The CSMA/CD protocol used by Ethernet for
accessing a shared medium is inherently half
duplex , and so is the 10BASE-T physical layer
where simultaneous transmit and receive
activity is interpreted as a collision.
Software overhead - By presenting a FIFO of
packets, the software driver does not have to
waste any time in calculating pointers for the
different buffers that make up different packets.
The driver usually deals with one packet at a
time. With this approach, packets are always
accessible at the same fixed address, and
access is provided to any byte of the packet.
The LAN91C95 supports two types of Full
Duplex operation:
1.
Full Duplex mode for diagnostic purposes
only, where the received packet is the
transmit packet being looped back. This
mode is enabled using the FDUPLX bit in
the TCR. In this mode the CSMA/CD
algorithm is used to gain access to the
media.
2.
FDSE (Full Duplex Switched Ethernet).
Enabled by FDSE bit in TCR bit. When the
LAN91C95 is configured for FDSE, its
transmit and receive paths will operate
independently
and
some
CSMA/CD
functions are disabled such as Carrier
Sense.
Headers can be analyzed without reading the
entire packet. The packet can be read or written
with a block move operation.
Multiple upper layer support - The LAN91C95
facilitates interfacing to multiple upper layer
protocols because of the receive packet
processing flexibility. A receive lookahead
scheme like ODI or NDIS drivers are supported
by copying a small part of the received packet
and letting the upper layer provide a pointer for
the rest of the data. If the upper layer indicates
83
collision is active during any of these states
the state machine transitions to JAM and
BACKOFF states.
Behavior in FDSE Mode
The main 802.3 section affected by FDSE is
4.2.8 where the Frame Transmission procedural
model is presented. The changes are:
1.
2.
3.
No deferral - The transmit channel is
dedicated and always available - The device
will transmit whenever it has a packet ready
to be sent, while respecting the interframe
spacing between transmit packets.
10BASE-T loopback - Typically 10BASE-T
drivers are internally looped back to the
differential receivers.
Magic Packet Support
If the WAKEUP_EN bit in the Control Register
(Bank1, Offset C) is set, the controller will come
out of any powerdown mode. If this bit is not
set, this functionality is disabled.
No collision detection - There are no
collisions in a switched environment.
The EPH implementation of the procedural
model uses as ‘collisionDetect’ the MAC
collision input, sourced from the 10BASE-T
front end, AUI front end, or External Endec
interface. This collision input is observed by
the Transmit State Machine while
‘transmitting’ is true, that is during
Preamble, Data, Pad, and CRC states. If
When a Magic Packet is received, the ethernet
controller will generate an interrupt causing the
host to initiate a service routine to find the
source of the event. The Interrupt bit in the
ECSR is also set if the host plans on polling the
controller for Wakeup status.
84
TYPICAL FLOW OF EVENTS FOR TRANSMIT
S/W DRIVER
CSMA/CD SIDE
1
ISSUE ALLOCATE MEMORY FOR TX - N
BYTES - the MMU attempts to allocate N bytes
of RAM.
2
WAIT FOR SUCCESSFUL COMPLETION
CODE - Poll until the ALLOC INT bit is set or
enable its mask bit and wait for the interrupt.
The TX packet number is now at the Allocation
Result Register.
3
LOAD TRANSMIT DATA - Copy the TX packet
number into the Packet Number Register.
Write the Pointer Register, then use a block
move operation from the upper layer transmit
queue into the Data Register.
4
ISSUE "ENQUEUE PACKET NUMBER TO TX
FIFO" - This command writes the number
present in the Packet Number Register into the
TX FIFO. The transmission is now enqueued.
No further CPU intervention is needed until a
transmit interrupt is generated.
5
The enqueued packet will be transferred to the
CSMA/CD block as a function of TXENA (n
TCR) bit and of the deferral process (in half
duplex mode) state.
6
Upon transmit completion the first word in
memory is written with the status word. The
packet number is moved from the TX FIFO into
the TX completion FIFO. Interrupt is generated
by the TX completion FIFO being not empty.
7
SERVICE INTERRUPT - Read Interrupt Status
Register. If it is a transmit interrupt, read the TX
Done Packet Number from the FIFO Ports
Register. Write the packet number into the
Packet Number Register. The corresponding
status word is now readable from memory. If
the status word shows successful transmission,
issue RELEASE packet number command to
free up the memory used by this packet.
Remove packet number from completion FIFO
by writing TX INT Acknowledge Register.
85
TYPICAL FLOW OF EVENTS FOR RECEIVE
S/W DRIVER
1
CSMA/CD SIDE
ENABLE RECEPTION - By setting the RXEN
bit.
2
A packet is received with matching address.
Memory is requested from MMU. A packet
number is assigned to it. Additional memory is
requested if more pages are needed.
3
The internal DMA logic generates sequential
addresses and writes the receive words into
memory. The MMU does the sequential to
physical address translation. If overrun, packet
is dropped and memory is released.
4
When the end of packet is detected, the status
word is placed at the beginning of the receive
packet in memory. The Byte count is placed at
the second word. If the CRC is correct, the
packet number is written into the RX FIFO. The
RX FIFO being not empty causes RCV INT
(interrupt) to be set. If CRC is incorrect the
packet memory is released and no interrupt will
occur.
5
SERVICE INTERRUPT - Read the Interrupt
Status Register and determine if RCV INT is
set. The next receive packet is at the receive
area. (Its packet number can be read from the
FIFO Ports Register). The software driver can
process the packet by accessing the RX area,
and can move it out to system memory if
desired. When processing is complete the CPU
issues the REMOVE AND RELEASE FROM
TOP OF RX command to have the MMU free
up the used memory and packet number.
86
ISR
Save Bank Select & Address
Ptr Registers
Mask 91C94 Interrupts
Read Interrupt Register
No
Yes
RX INTR?
Yes
TX INTR?
Call TX INTR or TXEMPTY
INTR
No
Call RXINTR
Get Next TX
Yes
ALLOC INTR?
Packet
Available for
Transmission?
No
Yes
Write Allocated Pkt # into
Packet Number Reg.
No
Call ALLOCATE
Write Ad Ptr Reg. & Copy Data
& Source Address
Enqueue Packet
EPH INTR?
Yes
Call EPH INTR
No
Restore Address Pointer &
Bank Select Registers
Unmask 91C94 Interrupts
Set "Ready for Packet" Flag
Return Buffers to Upper Layer
Disable Allocation Interrupt
Mask
Exit ISR
FIGURE 10 - ETHERNET INTERRUPT SERVICE ROUTINE
87
FIGURE 11 - INTERRUPT GENERATION FOR TRANSMIT, RECEIVE, MMU
88
OPTIONS
TWO
INTERRUPT
INT
ALLOC
INT
TX
TX EMPTY
INT
INT
RCV
STATUS REGISTER
M.S. BIT ONLY
PACKET NUMBER
TX DONE
'NOT EMPTY'
TX COMPLETIO N
FIFO
'EMPTY'
TX
FIFO
PACK # OUT
CPU ADDRESS
REGISTER
PACKET NUMBER
PACKET #
RAM
PHYSICAL ADDRESS
MMU
LOGICAL
ADDRESS
RX FIFO
NUMBER
RX PACKET
RX
FIFO
PACKET NUMBER
CSMA ADDRESS
'NOT EMPTY'
CSMA/CD
RX INTR
Write Ad. Ptr. Reg. & Read
Word 0 from RAM
Yes
Destination
Multicast?
No
Read Words 2, 3, 4 from RAM
for Address Filtering
No
Address
Filtering Pass?
Yes
No
Status Word
OK?
Yes
Do Receive Lookahead
Get Copy Specs from Upper
Layer
No
Okay to
Copy?
Yes
Copy Data Per Upper Layer
Specs
Issue "Remove and Release"
Command
Return to ISR
FIGURE 12 - RX INTR
89
TX INTR
Save Pkt Number Register
Read TXDONE Pkt # from
FIFO Ports Reg.
Write Into Packet Number
Register
Write Address Pointer Register
Read Status Word from RAM
Yes
No
TX Status
OK?
Update Statistics
Re-Enable TXENA
Immediately Issue "Release"
Command
Update Variables
Acknowledge TXINTR
Read TX INT Again
No
TX INT = 0?
Yes
Restore Packet Number
Return to ISR
FIGURE 13 - TX INTR
(Assumes Auto Release Option Selected)
90
TXEMPTY INTR
Write Acknowledge Reg. with
TXEMPTY Bit Set
Read TXEMPTY & TX INTR
TXEMPTY = 0
&
TXINT = 0
(Waiting for Completion)
TXEMPTY = X
&
TXINT = 1
(Transmission Failed)
TXEMPTY = 1
&
TXINT = 0
(Everything went through
successfully)
Read Pkt. # Register & Save
Write Address Pointer
Register
Read Status Word from RAM
Update Statistics
Issue "Release" Command
Acknowledge TXINTR
Re-Enable TXENA
Restore Packet Number
Return to ISR
FIGURE 14 - TXEMPTY INTR
91
Update Variables
DRIVER SEND
ALLOCATE
Choose Bank Select
Register 2
Issue "Allocate Memory"
Command to MMU
Call ALLOCATE
Read Interrupt Status Register
Exit Driver Send
Yes
Allocation
Passed?
No
Read Allocation Result
Register
Write Allocated Packet into
Packet # Register
Store Data Buffer Pointer
Write Address Pointer Register
Clear "Ready for Packet" Flag
Copy Part of TX Data Packet
into RAM
Enable Allocation Interrupt
Write Source Address into
Proper Location
Copy Remaining TX Data
Packet into RAM
Enqueue Packet
Set "Ready for Packet" Flag
Return Buffers to Upper Layer
Return
FIGURE 15 - DRIVER SEND AND ALLOCATE ROUTINES
92
driver does not need to enqueue transmissions,
it can allow more memory to be allocated for
receive (by reducing the value of the reserved
memory). Whenever the driver needs to burst
transmissions it can reduce the receive memory
allocation. The driver program the parameter as
a function of the following variables:
MEMORY PARTITIONING
Unlike other controllers, the LAN91C95 does not
require a fixed memory partitioning between
transmit and receive resources. The MMU
allocates and de-allocates memory upon
different events.
An additional mechanism
allows the CPU to prevent the receive process
from starving the transmit memory allocation.
1)
2)
Memory is always requested by the side that
needs to write into it, that is: the CPU for
transmit or the CSMA/CD for receive. The CPU
can control the number of bytes it requests for
transmit but it cannot determine the number of
bytes the receive process is going to demand.
Furthermore, the receive process requests will
be dependent on network traffic, in particular on
the arrival of broadcast and multicast packets
that might not be for the node, and that are not
subject to upper layer software flow control.
Free memory (read only register)
Memory size (read only register)
The reserved memory value can be changed on
the fly. If the MEMORY RESERVED FOR TX
value is increased above the FREE MEMORY,
receive packets in progress are still received,
but no new packets are accepted until the FREE
MEMORY increases above the MEMORY
RESERVED value.
INTERNAL VS.
MEMORY MAP
EXTERNAL
ATTRIBUTE
The Internal vs. External EPROM attribute memory
decodes are shown in Table 13 and Table 14. This
allows the designer to not require an external
EPROM device if the single or multi-function
PCMCIA card needs less than 512 bytes of
configuration information. As can be seen in the
map, if 512 bytes of CIS or less is required, the
nFCS and nFWE output pins of the LAN91C95
need not be used (if serial EEPROM is being used).
Internal to the LAN91C95, the memory addressing
logic will allow byte or word access on even byte
boundaries. This implies that on odd byte address
access (A0=1), the LAN91C95 will generate a
arbitrary value of Zero (0) since the PCMCIA
specification states that the high byte of a word
access in attribute memory is a don’t care. This
allows backward compatibility to 8 bit hosts.
In order to prevent unwanted traffic from using
too much memory, the CPU can program a
"memory reserved for transmit" parameter. If
the free memory falls below the "memory
reserved for transmit" value, MMU requests
from the CSMA/CD block will fail and the
packets will overrun and be ignored. Whenever
enough memory is released, packets can be
received again. If the reserved value is too
large, the node might lose data which is an
abnormal condition. If the value is kept at zero,
memory allocation is handled on first-come firstserved basis for the entire memory capacity.
Note that with the memory management built
into the LAN91C95, the CPU can dynamically
program this parameter. For instance, when the
93
TABLE 13 - ATTRIBUTE MEMORY DECODES USING SERIAL EPROM
ATTRIBUTE
MEMORYADDRESS
EXTERNAL EPROM
STORE
0 - 3FEh
INTERNAL SRAM
STORE (512 BYTES)
CONFIGURATION
REGISTERS
X
400h-7FFEh
X
8000h - 803Eh
X
TABLE 14 - ATTRIBUTE MEMORY DECODES WITHOUT SERIAL EPROM
ATTRIBUTE
MEMORYADDRESS
0 - 7FFEh
EXTERNAL EPROM
STORE
INTERNAL SRAM
STORE (512 BYTES)
CONFIGURATION
REGISTERS
X
8000h - 803Eh
X
94
1) One interrupt per packet: enable TX INT,
set AUTO RELEASE=0. The software driver
can find the completion result in memory and
process the interrupt one packet at a time.
Depending on the completion code the driver
will take different actions. Note that the transmit
process is working in parallel and other
transmissions might be taking place.
The
LAN91C95 is virtually queuing the packet
numbers and their status words.
INTERRUPT GENERATION
The interrupt strategy for the transmit and
receive processes is such that it does not
represent the bottleneck in the transmit and
receive queue management between the
software driver and the controller. For that
purpose there is no register reading necessary
before the next element in the queue (namely
transmit or receive packet) can be handled by
the controller. The transmit and receive results
are placed in memory.
The receive interrupt will be generated when the
receive queue (FIFO of packets) is not empty
and receive interrupts are enabled. This allows
the interrupt service routine to process many
receive packets without exiting, or one at a time
if the ISR just returns after processing and
removing one.
In this case, the transmit interrupt service
routine can find the next packet number to be
serviced by reading the TX DONE PACKET
NUMBER at the FIFO PORTS register. This
eliminates the need for the driver to keep a list
of packet numbers being transmitted. The
numbers are queued by the LAN91C95 and
provided back to the CPU as their transmission
completes.
There are two types of transmit interrupt
strategies:
1) One interrupt per packet
2) One interrupt per sequence of packets
2) One interrupt per sequence of packets:
Enable TX EMPTY INT and TX INT, set AUTO
RELEASE=1. TX EMPTY INT is generated only
after transmitting the last packet in the FIFO.
The strategy is determined by how the transmit
interrupt bits and the AUTO RELEASE bit are
used.
TX INT will be set on a fatal transmit error
allowing the CPU to know that the transmit
process has stopped and therefore the FIFO will
not be emptied.
TX INT bit - Set whenever the TX completion
FIFO is not empty.
This mode has the advantage of a smaller CPU
overhead, and faster memory de-allocation.
Note that when AUTO RELEASE=1 the CPU is
not provided with the packet numbers that
completed successfully.
TX EMPTY INT bit - Set whenever the TX FIFO
is empty.
AUTO RELEASE - When set, successful
transmit packets are not written into completion
FIFO, and their memory is released
automatically.
Note: The pointer register is shared by any
process accessing the LAN91C95 memory. In
order to allow processes to be interruptable,
the interrupting process is responsible for
reading the pointer value before modifying it,
saving it, and restoring it before returning from
the interrupt.
95
3)
Typically there would be three processes using
the pointer:
1)
2)
Transmit Status reading (interrupt driven)
1) and 3) also share the usage of the Packet
Number Register. Therefore saving and
restoring the PNR is also required from interrupt
service routines.
Transmit loading (sometimes interrupt
driven)
Receive unloading (interrupt driven)
96
FUNCTIONAL DESCRIPTION OF THE BLOCKS
can allocate, therefore there is no need for the
programmer or the hardware to check FIFO full
conditions.
MEMORY MANAGEMENT UNIT
The MMU interfaces the on-chip RAM on one
side and the arbiter on the other for address and
data flow purposes. For allocation and deallocation, it interfaces the arbiter only.
ARBITER
The function of the arbiter is to sequence packet
RAM accesses as well as MMU requests in such
a way that the on-chip single ported RAM and a
single MMU can be shared by two parties. One
party is the host CPU and the other party is the
CSMA/CD block.
The MMU deals with a single ported memory
and is not aware of the fact that there are two
entities requesting allocation and actually
accessing memory. The mapping function done
by the MMU is only a function of the packet
number accessed and of the offset within that
packet being accessed. It is not a function of
who is requesting the access or the direction of
the access.
The arbiter is address transparent, namely, any
address can be accessed at any time. In order
to exploit the sequential nature of the access,
and minimize the access time on the system
side, the CPU cycle is buffered by the Data
Register rather than go directly to and from
memory. Whenever a write cycle is performed,
the data is written into the Data Register and will
be written into memory as a result of that
operation, allowing the CPU cycle to complete
before the arbitration and memory cycle are
complete. Whenever a read cycle is performed,
the data is provided immediately from the Data
Register, without having to arbitrate and
complete a memory cycle. The present cycle
results in an arbitration request for the next data
location. Loading the pointer causes a similar
pre-fetch request.
To accomplish that, memory accesses as well
as MMU allocation and de-allocation requests
are arbitrated by the arbiter block before
reaching the MMU.
Memory allocation could take some time, but
the ALLOC INT bit in Interrupt Status Register is
negated immediately upon allocation request,
allowing the system to poll that register at any
time.
Memory de-allocation command
completion indication is provided via the BUSY
bit, readable through the MMU command
register.
The mapping and queuing functions of the MMU
rely on the uniqueness of the packet number
assigned to the requester. For that purpose the
packet number assignment is centralized at the
MMU, and a number will not be reused until the
memory associated with it is released. It is
clear that a packet number should not be
released while the number is in the TX or RX
packet queue.
This type of read-ahead and write-behind
arbitration allows the controller to have a very
fast access time, and would work without wait
states for as long as the cycle time spec. is
satisfied. The values are 40 ns access time,
and 185ns cycle time.
By the same token, CSMA/CD cycles might be
postponed. The worst case CSMA/CD latency
for arbiter service is one memory cycle.
The TX and RCV FIFOs are deep enough to
handle the total number of packets the MMU
97
glitch through a valid value. Only when nIORD
or nIOWR are activated the I/O cycle begins.
The arbiter uses the pointer register as the CPU
provided address, and the internal DMA address
from the CSMA/CD side as the addresses to be
provided to the MMU.
In PCMCIA mode, A4-A15 are ignored for I/O
decodes, which rely on the PCMCIA host
decoding for the slot. Input A10 for ISA is used
as an output (nFWE) for PCMCIA to enable
Flash Memory Write for programming the
attribute memory. It is valid only when nWE is
0 and COR2 is 1. nA11/nFCS is used to select
the Flash Memory Chip.
The data path routed by the arbiter goes
between memory (the data path does not go
through the MMU) on one side and either the
CPU side bus or the data path of the CSMA/CD
core.
The data path between memory and the Data
Register is in fact buffered by a small FIFO in
each direction. The FIFOs beneath the Data
Register can be read and written as bytes or
words, in any sequential combination. The
presence of these FIFOs makes sure that word
transfers are possible on the system bus even if
the address loaded into the pointer is odd.
WAIT STATE POLICY
The LAN91C95 can work on most system buses
without having to add wait states. The two
parameters that determine the memory access
profile are the read access time and the cycle
time into the Data Register.
The read access time is 40ns and the cycle time
is 185ns. If any one of them does not satisfy
the application requirements, wait states should
be added.
BUS INTERFACE
The bus interface handles the data, address and
control interfaces as a superset of the ISA and
PCMCIA specifications and allows 8 or 16 bit
adapters to be designed with the LAN91C95
with no glue to interface to the ISA or PCMCIA
bus.
If the access time is the problem, IOCHRDY
should be negated for all accesses to the
LAN91C95.
This can be achieved by
programming the NO WAIT ST bit in the
configuration register to 0. The LAN91C95 will
negate IOCHRDY for 100ns to 150ns on every
access to any register.
The functions done in this block are address
decoding for I/O and ROM memory (including
address relocation support) for ISA, data path
routing, sequential memory address support,
optional wait state generation, boot ROM
support, EEPROM setup function, bus
transceiver
control,
and
interrupt
generation/selection.
If the cycle time is the problem, programming
NO WAIT ST as described before will solve it
but at the expense of slowing down all
accesses.
The alternative is to let the
LAN91C95 negate IOCHRDY only when the
Data Register FIFOs require so. Namely, if NO
WAIT ST is set, IOCHRDY will only be negated
if a Data Register read cycle starts and there is
less than a full word in the read FIFO, or if a
write cycle starts and there is more than two
bytes in the write FIFO.
For ISA, I/O address decoding is done by
comparing A15-A4 to the I/O BASE address
determined in part by the upper byte of the
BASE ADDRESS REGISTER, and also
requiring that AEN be low. If the above address
comparison is satisfied and the LAN91C95 is in
16 bit mode, nIOCS16 will be asserted (low).
The cycle time is defined as the time between
leading edges of read from the Data Register, or
equivalently between trailing edges of write to
the Data Register. For example, in an ISA
A valid comparison does not yet indicate a valid
I/O cycle is in progress, as the addresses could
be used for a memory cycle, or could even
98
the MMU. However the DMA logic controls
the removal of the PACKET NUMBER from
the FIFO.
system the cycle time of a 16 bit transfer will be
at least 2 clocks for the I/O access to the
LAN91C95 + one clock for the memory cycle) =
3 clocks. In absolute time it means 375ns for a
8MHz bus, and 240ns for a 12.5 MHz bus.
2)
The cycle time will not increase when configured
for full duplex mode, because the CSMA/CD
memory arbitration requests are sequenced by
the DMA logic and never overlap.
Generation of CSMA/CD side addresses
into memory: Independent 11 bit counters
are kept for transmit and receive in order to
allow full-duplex operation.
3)
MMU requests for allocation are generated
by the DMA logic upon reception. The
initial allocation request is issued when the
CSMA block indicates an active reception. If
allocation succeeds, the DMA block stores
the packet number assigned to it, and
generates write arbitration requests for as
long as the CSMA/CD FIFO is not empty.
In parallel the CSMA/CD completes the
address filtering and notifies the DMA of an
address match. If there is no address
match, the DMA logic will release the
allocated memory and stop reception.
4)
When the CSMA/CD block notifies the DMA
logic that a receive packet was completed,
if the CRC is OK, the DMA will either write
the previously stored packet number into
the RX PACKET NUMBER FIFO (to be
processed by the CPU), or if the CRC is
bad the DMA will just issue a release
command to the MMU (and the CPU will
never see that packet).
DMA BLOCK
The DMA block resides between the CSMA/CD
block and the arbiter. It can interface both the
data path and the control path of the CSMA/CD
block for different operations.
Its functions include the following:
•
•
•
•
•
•
•
•
•
•
Start transmission process into the
CSMA/CD block.
Generate CSMA/CD side addresses for
accessing memory during transmit and
receive operations.
Generate MMU memory requests and verify
success.
Compute byte count and write it in first
locations of receive packet.
Write transmit status word in first locations
of transmit packet.
Determine if enough memory is available
for reception.
De-allocate transmit memory after suitable
completion.
De-allocate receive memory upon error
conditions.
Initiate retransmissions upon collisions (if
less than 16 retries).
Terminate reception and release memory if
packet is too long.
Packets with bad CRC can be received if
the RCV_BAD bit in the configuration
register is set.
5)
The specific nature of each operation and its
trigger event are:
1)
6)
TX operations will begin if TXENA is set
and TX FIFO is not empty. The DMA logic
does not need to use the TX PACKET
NUMBER, it goes directly from the FIFO to
99
If AUTO_RELEASE is set, a release is
issued by the DMA block to the MMU after a
successful transmission (TX_SUCC set),
and the TX completion FIFO is clocked
together with the TX FIFO preventing the
packet number from moving into the TX
completion FIFO.
Based on the RX counter value, if a receive
packet exceeds 1532 bytes, reception is
stopped by the DMA and the RX ABORT bit
in the Receive Control Register is set. The
memory allocated to the packet is
automatically released.
7)
The receive packet FIFO stores the packet
numbers already received into memory, in the
order they were received.
The FIFO is
advanced (written) by the DMA block upon
reception of a complete valid packet into
memory.
The number is determined the
moment the DMA block first requests memory
from the MMU for that packet. The first receive
packet number in the FIFO can be read via the
Fifo Ports Register, and the data associated
with it can be accessed through the receive
area. The packet number can be removed
from the FIFO with or without an automatic
release of its associated memory.
If an allocation fails, the CSMA/CD block
will activate RX_OVRN upon detecting a
FIFO full condition. RXEN will stay active to
allow reception of subsequent packets if
memory becomes available.
The
CSMA/CD block will flush the FIFO upon
the new frame arrival.
PACKET NUMBER FIFOS
The transmit packet FIFO stores the packet
numbers awaiting transmission, in the order
they were enqueued. The FIFO is advanced
(written) when the CPU issues the "enqueue
packet number command", the packet number
to be written is provided by the CPU via the
Packet Number Register. The number was
previously obtained by requesting memory
allocation from the MMU. The FIFO is read by
the DMA block when the CSMA/CD block is
ready to proceed on to the next transmission.
By reading the TX EMPTY INT bit the CPU can
determine if this FIFO is empty.
The FIFO is read out upon CPU command
(remove packet from top of RX FIFO, or remove
and release command) after processing the
receive packet in the receive area.
The width of each FIFO is 5 bits per packet
number. The depth of each FIFO equals the
number of packets the LAN91C95 can handle
(18).
The guideline is software transparency; the
software driver should not be aware of different
devices or FIFO depths. If the MMU memory
allocation succeeded, there will be room in the
transmit FIFO for enqueuing the packet.
Conversely if there is free memory for receive,
there should be room in the receive FIFO for
storing the packet number.
The transmit completion FIFO stores the packet
numbers that were already transmitted but not
yet acknowledged by the CPU. The CPU can
read the next packet number in this FIFO from
the Fifo Ports Register. The CPU can remove a
packet number from this FIFO by issuing a TX
INT acknowledge. The CPU can determine if
this FIFO is empty by reading the TX INT bit or
the FIFO Ports Register.
Note that the CPU can enqueue a transmit
command with a packet number that does not
follow the sequence in which the MMU assigned
packet numbers. For example, when a
transmission failed and it is retried in software,
or when a receive packet is modified and sent
back to the network.
100
FIGURE 16 - MMU PACKET NUMBER FLOW AND RELEVANT REGISTERS
101
DECODER
RESULT REGISTER
ALLOCATION
REGISTER
COMMAND
MMU
PACK # OUT
RELEASE
ALLOCATE
CPU ADDRESS
PACKET NUMBER
TX DONE
LOGICAL
ADDRESS
PACKET #
RAM
PACK # OUT
PHYSICAL ADDRESS
MMU
RELEASE
ALLOCATE
CSMA ADDRESS
NUMBER
RX
FIFO
RX PACKET
RD
FIFO
WR
RX FIFO
DMA
PACKET NUMBER
TX
COMPLETION
TX
FIFO
REGISTER
PACKET NUMBER
CSMA/CD
Note that the receive status word of any packet
is available only through memory and is not
readable through any other register. In order to
let the CPU know about receive overruns, the
RX_OVRN bit is latched into the Interrupt Status
Register, which is readable by the CPU at any
time.
CSMA BLOCK
The CSMA/CD block is first interfaced via its
control registers in order to define its operational
configuration. From then on, the DMA interface
between the CSMA/CD block and memory is
used to transfer data to and from its data path
interface.
The address filtering is done inside the
CSMA/CD block. A packet will be received if the
destination address is broadcast, or if it is
addressed to the individual address of the
LAN91C95, or if it is a multicast address and
ALMUL bit is set, or if it is a multicast address
matching one of the multicast table entries. If
the PRMS bit is set, all packets are received.
For transmit, the CSMA/CD block will be asked
to transmit frames as soon as they are ready in
memory. It will continue transmissions until any
of the following transmit error occurs:
a)
b)
c)
d)
e)
16 collisions on same frame (half duplex
mode)
Late collision (half duplex mode)
Lost Carrier sense and MON_CSN set
Transmit Under run
SQET error and STP_SQET set
The CSMA/CD block is a full duplex machine,
and when working in full duplex mode, the
CSMA/CD block will be simultaneously using its
data path transmit and receive interfaces.
In that case TXENA will be cleared and the CPU
should restart the transmission by setting it
again. If a transmission is successful, TXENA
stays set and the CSMA/CD is provided by the
DMA block with the next packet to be
transmitted.
Statistical counters are kept by the CSMA/CD
block, and are readable through the appropriate
register. The counters are four bits each, and
can generate an interrupt when reaching their
maximum values.
Software can use that
interrupt to update statistics in memory, or it can
keep the counter interrupt disabled, while relying
on the transmit interrupt routine reading the
counters.
Given that the counters can
increment only once per transmit, this technique
is a good complement for the single interrupt
per sequence strategy.
For receive, the CPU sets RXEN as a way of
starting the CSMA/CD block receive process.
The CSMA/CD block will send data after
address filtering through the data path to the
DMA block. Data is transferred into memory as
it is received, and the final check on data
acceptance is the CRC checking done by the
CSMA/CD block. In any case, the DMA takes
care of requesting/releasing memory for receive
packets, as well as generating the byte count.
The interface between the CSMA/CD block and
memory is word oriented. Two bi-directional
FIFOs make the data path interface.
Whenever a normal collision occurs (less than
16 retries - half duplex mode), the CSMA/CD will
trigger the backoff logic and will indicate the
DMA logic of the collision.
The DMA is
responsible for restarting the data transfer into
the CSMA/CD block regardless of whether the
collision happened on the preamble or not.
The receive status word is provided by the
CSMA/CD block and written in the first location
of the receive structure by the DMA block. If
configured for storing CRC in memory, the
CSMA/CD unit will transfer the CRC bytes
through the DMA interface, and then will be
treated like regular data bytes.
Only when 16 retries are reached, the CSMA/CD
block will clear the TXENA bit, and CPU
intervention is required. The DMA will not
102
transmission, data is automatically looped back
to the receiver except during collision periods, in
which case the input to the receiver is network
data. During collisions, should the receive input
go idle prior to the transmitter going idle, input
to the receiver switches back to the transmitter
within 9 bit times. Following transmission, the
transmitter performs a SQE test. This test
exercises the collision detection circuitry within
the 10BASE-T interface.
automatically restart data transfer in this case,
nor will it transmit the next enqueued packet
until TXENA is set by the CPU. The DMA will
move the packet number in question from the
TX FIFO into the TX completion FIFO.
NETWORK INTERFACE
The LAN91C95 includes both an AUI interface
for thick and thin coax applications and a
10BASE-T interface for twisted pair applications.
Functions common to both are:
1.
2.
3.
4.
5.
In full duplex mode, carrier sense is asserted
during receive activity only.
The receiver
monitors the media at all times. It recovers the
clock and data and passes it along to the
controller. In the absence of any receive activity,
the transmitter is looped back to the receiver. In
addition, the receiver performs automatic
polarity correction. The 10BASE-T interface
performs link integrity tests per section 14.2.1.7
of 802.3, using the following values:
Manchester encoder/decoder to convert
NRZ data to Manchester encoded data and
back.
A 32 ms jabber timer to prevent
inadvertently long transmissions. When
'jabbing' occurs, the transmitter is disabled,
automatic loopback is disabled (in 10BASET mode), and a collision indication is given
to the controller. The interface 'unjabs'
when the transmitter has been idle for a
minimum of 256 ms.
A phase-lock loop to recover data and clock
from the Manchester data stream with up to
plus or minus 18ns of jitter.
Diagnostic loopback capability.
LED drivers for collision, transmission,
reception, and jabber.
1.
2.
3.
4.
Link_loss_timer: 64 ms
Link_test_min_timer: 4 ms
Link_count: 2
Link_test_max_timer: 64 ms
The state of the link is reflected in the EPHSR.
AUI
The LAN91C95 also provides a standard 6 wire
AUI interface to a coax transceiver.
10BASE-T
The 10BASE-T interface conforms to the twisted
pair MAU addendum to the 802.3 specification.
On the transmission side, it converts the NRZ
data from the controller to Manchester data and
provides the appropriate signal level for driving
the media. Signal are predistorted before
transmission to minimize ISI. In half duplex
mode, the collision detection circuitry monitors
the simultaneous occurrence of received signals
and transmitted data on
the media. During
PHYSICAL INTERFACE
The internal physical interface (PHY) consists of
an encoder/decoder (ENDEC) and an internal
10BASE-T transceiver.
The ENDEC also
provides a standard 6-pin AUI interface to an
external coax transceiver for 10BASE-T and
10BASE-5 applications. The signals between
MAC and the PHY can be routed to pins by
asserting the nXENDEC pin low.
This
feature allows the interface to an external
ENDEC and transceiver. The PHY functions
can be divided into transmit and receive
functions.
103
Transmit Functions
Receive Functions
Manchester Encoding
Receive Drivers
The PHY encodes the transmit data received
from the MAC. The encoded data is directed
internally to the selected output driver for
transmission over the twisted-pair network or
the AUI cable. Data transmission and encoding
is initiated by the Transmit Enable input, TXE,
going low.
Differential signals received off the twisted-pair
network or AUI cable are directed to the internal
clock recovery circuit prior to being decoded for
the MAC.
Manchester Decoder and Clock Recovery
The PHY performs timing recovery and
Manchester decoding of incoming differential
signals in 10BASE-T or AUI modes, with its
built-in phase-lock loop (PLL). The decoded
(NRZ) data, RXD, and the recovered clock,
RXCLK, becomes available to the MAC,
typically within 9 bit times (5 for AUI) after the
assertion of nCRS. The receive clock, RXCLK,
is phase-locked to the transmit clock in the
absence of a received signal (idle).
Transmit Drivers
The encoded transmit data passes through to
the transmit driver pair, TPETXP(N), and its
complement, TPETXDP(N). Each output of the
transmit driver pair has a source resistance of
10 ohms maximum and a current rating of 25
mA maximum. The degree of predistortion is
determined by the termination resistors; the
equivalent resistance should be 100 ohms.
Squelch Function
Jabber Function
The integrated smart squelch circuit employs a
combination
of
amplitude
and
timing
measurements to determine the validity of data
received off the network. It prevents noise at the
differential inputs from falsely triggering the
decoder in the absence of valid data or link test
pulses. Signal levels below 300mV (180mV for
AUI) or pulse widths less than 15ns at the
differential inputs are rejected. Signals above
585mV (300mV for AUI) and pulse widths
greater than 30ns will be accepted. When using
the extended cable mode with 10BASE-T media
which extends beyond the standard limit of 100
meters, the squelch level can optionally be set
to reject signals below 180mV and accept
signals above 300mV.
If the input signal
exceeds the squelch requirements, the carrier
sense output, nCRS, is asserted.
This integrated function prevents the DTE from
locking into a continuous transmit state. In
10BASE-T mode, if transmission continues
beyond the specified time limit, the jabber
function inhibits further transmission and
asserts the collision indicator nCOLL. The limits
for jabber transmission are 20 to 15 ms in
10BASE-T mode. In the AUI mode, the jabber
function is performed by the external
transceiver.
SQE Function
In the 10BASE-T mode, the PHY supports the
signal quality error (SQE) function. At the end
of a transmission, the PHY asserts the nCOLL
signal for 10+/-5 bit times beginning 0.6 to
1.6ms after the last positive transition of a
transmitted frame. In the AUI mode, the SQE
function is performed by the external
transceiver.
104
transceiver sends a 10MHz signal to the PHY
upon detection of a collision.
Reverse Polarity Function
In the 10BASE-T mode, the PHY monitors for
receiver polarity reversal due to crossed wires
and corrects by reversing the signal internally.
Collision Detection Function
Link Integrity
The PHY test for a faulty twisted-pair link. In the
absence of transmit data, link test pulses are
tranmsitted every 16+/-18ms after the end of the
last transmission or link pulse on the twisted
pair medium. If neither valid data nor link test
pulses are received within 10 to 150ms, the link
is declared bad and both data transmission as
well as the operational loopback function are
disabled. The Link Integrity function can be
disabled
for
pre-10BASE-T
twisted-pair
networks.
In the 10BASE-T mode, while in half duplex, a
collision state is indicated when there are
simultaneous transmissions and receptions on
the twisted pair link. During a collision state, the
nCOLL signal is asserted. If the received data
ends and the transmit control signal is still
active, the transmit data is sent to the MAC
within 9 bit times. The nnCOLL signal is deasserted within 9 bit times after the collision
terminates. In the AUI mode, the external
105
BOARD SETUP INFORMATION
ISA MODE
The following parameters are obtained from the
EEPROM as board setup information:
REGISTER
Configuration
Register
ETHERNET INDIVIDUAL ADDRESS
I/O BASE ADDRESS
ROM BASE ADDRESS
8/16 BIT ADAPTER
10BASE-T or AUI INTERFACE
INTERRUPT LINE SELECTION
Base Register
EEPROM WORD
ADDRESS
IOS Value * 4
(IOS Value *4) + 1
INDIVIDUAL ADDRESS
20-22 hex
If IOS2-IOS0=7, only the INDIVIDUAL
ADDRESS is read from the EEPROM.
Currently assigned values are assumed for the
other registers. These values are default if the
EEPROM read operation follows hardware
reset.
All the above mentioned values are read from
the EEPROM upon hardware reset. Except for
the INDIVIDUAL ADDRESS, the value of the
IOS switches determines the offset within the
EEPROM for these parameters, in such a way
that many identical boards can be plugged into
the same system by just changing the IOS
jumpers.
The EEPROM SELECT bit is used to determine
the type of EEPROM operation: a) normal or b)
general purpose register.
In order to support a software utility based
installation, even if the EEPROM was never
programmed, the EEPROM can be written using
the LAN91C95. One of the IOS combination is
associated with a fixed default value for the key
parameters
(I/O
BASE,
ROM
BASE,
INTERRUPT) that can always be used
regardless of the EEPROM based value being
programmed. This value will be used if all IOS
pins are left open or pulled high.
a)
NORMAL
EEPROM
OPERATION
EEPROM SELECT bit = 0
-
On EEPROM read operations (after reset or
after
setting
RELOAD
high)
the
CONFIGURATION REGISTER and BASE
REGISTER are updated with the EEPROM
values at locations defined by the IOS2-0 pins.
The INDIVIDUAL ADDRESS registers are
updated with the values stored in the
INDIVIDUAL ADDRESS area of the EEPROM.
The EEPROM is arranged as a 64 x 16 array.
The specific target device is the 9346 1024-bit
Serial EEPROM. All EEPROM accesses are
done in words. All EEPROM addresses shown
are specified as word addresses.
On EEPROM write operations (after setting the
STORE
bit)
the
values
of
the
CONFIGURATION REGISTER and BASE
REGISTER are written in the EEPROM
locations defined by the IOS2-0 pins.
106
The three least significant bits of the CONTROL
REGISTER (EEPROM SELECT, RELOAD and
STORE) are used to control the EEPROM. Their
values are not stored nor loaded from the
EEPROM.
DIAGNOSTIC LEDs
The following LED drive signals are available for
diagnostic and installation aid purposes:
nTXLED - Activated by transmit activity.
b)
GENERAL
PURPOSE
EEPROM SELECT bit = 1
REGISTER
nBSELED - Board select LED. Activated when
the board space is accessed, namely on
accesses to the LAN91C95 register space or the
ROM area decoded by the LAN91C95. The
signal is stretched to 125 msec.
On EEPROM read operations (after setting
RELOAD high) the EEPROM word address
defined by the POINTER REGISTER 6 least
significant bits is read into the GENERAL
PURPOSE REGISTER.
nRXLED - Activated by receive activity.
On EEPROM write operations (after setting the
STORE bit) the value of the GENERAL
PURPOSE REGISTER is written at the
EEPROM word address defined by the
POINTER REGISTER 6 least significant bits.
nLINKLED - Reflects the link integrity status.
ARBITRATION CONSIDERATIONS
The arbiter exploits the sequential nature of the
CPU accesses to provide a very fast access
time. Memory bandwidth considerations will
have an effect on the CPU cycle time but no
effect on access time.
RELOAD and STORE are set by the user to
initiate read and write operations respectively.
Polling the value until read low is used to
determine completion.
When an EEPROM
access is in progress the STORE and RELOAD
bits of CTR will readback as both bits high. No
other bits of the LAN91C95 can be read or
written until the EEPROM operation completes
and both bits are clear. This mechanism is also
valid for reset initiated reloads.
For normal 8 MHz, 10 MHz and 12.5 MHz ISA
buses as well as EISA normal cycles the
LAN91C95 can be accessed without negating
ready.
When write operations occur, the data is written
into a FIFO. The CPU cycle can complete
immediately, and the buffered data will be
written into memory later.
The memory
arbitration request is generated as a function of
that FIFO being not empty. The nature of the
cycle requested (byte/word) is determined by the
lsb of the pointer and the number of bytes in the
FIFO.
NOTE: If no EEPROM is connected to the
LAN91C95, for example for some embedded
applications, the ENEEP pin should be
grounded and no accesses to the EEPROM will
be attempted. Configuration, Base, and
Individual Address assume
their
default
values upon hardware reset and the CPU is
responsible for programming them for their final
value.
When read operations occur, words are prefetched upon pointer loading in order to have at
least a word ready in the FIFO to be read. New
pre-fetch cycles are requested as a function of
the number of bytes in the FIFO.
107
be two or three bytes in the FIFO and a full word
can be written into the now even memory
address.
For example, if an odd pointer value is loaded,
first a byte is pre-fetched into the FIFO, and
immediately a full word is pre-fetched
completing three bytes into the FIFO. If the CPU
reads a word, one byte will be left again a new
word is pre-fetched.
When a CSMA/CD cycle begins, the arbiter will
route the CSMA/CD DMA addresses to the MMU
as well as the packet number associated with
the operation in progress. In full-duplex mode,
receive and transmit requests are alternated in
such a way that the CPU arbitration cycle time
is not affected.
In the case of write, if an odd pointer value is
loaded, and a full word is written, the FIFO
holds two bytes, the first of which is immediately
written into an odd memory location. If by that
time another byte or word was written, there will
108
16 BITS
IOS2-0
WORD ADDRESS
000
0h
C O N F I G U R ATION REG.
1h
BASE REG.
4h
C O N F I G U R ATION REG.
5h
BASE REG.
8h
C O N F I G U R ATION REG.
9h
BASE REG.
Ch
C O N F I G U R ATION REG.
Dh
BASE REG.
10h
C O N F I G U R ATION REG.
11h
BASE REG.
14h
C O N F I G U R ATION REG.
15h
BASE REG.
18h
C O N F I G U R ATION REG.
19h
BASE REG.
20h
IA0-1
21h
IA2-3
22h
IA4-5
001
010
011
100
101
110
XXX
FIGURE 17 - 64 X 16 SERIAL EEPROM MAP FOR ISA MODE
109
ATTRIBUTE MEMORY
HOST ADDRESS (HEX)
000
001
002
003
004
005
006
..
3F8
3F9
3FA
3FB
3FC
3FD
3FE
3FF
Table 15 PCMCIA - EEPROM to SRAM Memory Map
ATTRIBUTE
EEPROM ADDRESS
DATA
IN WORDS
Data Byte 0
Word 1 - Low Byte
Don’t Care
Data Byte 1
Word 1 - High Byte
Don’t Care
Data Byte 2
Word 2 - Low Byte
Don’t Care
Data Byte 3
Word 2 - High Byte
..
..
Data Byte 1FC
Word FE - Low Byte
Don’t Care
Data Byte 1FD
Word FE- High Byte
Don’t Care
Data Byte 1FE
Word FF - Low Byte
Don’t Care
Data Byte 1FF
Word FF - High Byte
Don’t Care
Note: This memory map assumes a 4096 bit Serial EEPROM in PCMCIA mode.
110
LAN91C95 SRAM
IN BYTES
Byte 0
Byte1
Byte2
Byte3
..
Byte FC
Byte1FD
Byte1FE
Byte1FF
OPERATIONAL DESCRIPTION
MAXIMUM GUARANTEED RATINGS*
Operating Temperature Range........................................................................................0o C to +70o C
Storage Temperature Range .....................................................................................-55o C to +150o C
Lead Temperature Range (soldering, 10 seconds) .................................................................. +325o C
Positive Voltage on any pin, with respect to Ground ............................................................Vcc + 0.3V
Negative Voltage on any pin, with respect to Ground ................................................................... -0.3V
Maximum Vcc ............................................................................................................................... +7V
*Stresses above those listed above could cause permanent damage to the device. This is a stress
rating only and functional operation of the device at any other condition above those indicated in the
operation sections of this specification is not implied.
Note: When powering this device from laboratory or system power supplies, it is important that the
Absolute Maximum Ratings not be exceeded or device failure can result. Some power supplies exhibit
voltage spikes on their outputs when the AC power is switched on or off. In addition, voltage
transients on the AC power line may appear on the DC output. If this possibility exists, it is suggested
that a clamp circuit be used.
DC ELECTRICAL CHARACTERISTICS (TA = 0o C - 70o C, Vcc = +5.0 V ± 10%)
PARAMETER
Current Supply
Active
Current Supply
SYMBOL
MIN
ICC
TYP
MAX
TBD
TBD
Powerdown (Ethernet)
Current Supply
ICCPDN
TBD
TBD
Magic Packet Mode
I Type Input Buffer
ICCMP
TBD
TBD
Low Input Level
VILI
High Input Level
IS Type Input Buffer
VIHI
Low Input Level
VILIS
High Input Level
VIHIS
Schmitt Trigger Hysteresis
VHYS
0.8
2.0
UNITS
COMMENTS
Magic Packet
Scanning
Disabled
V
TTL Levels
V
0.8
2.2
250
111
V
Schmitt Trigger
V
Schmitt Trigger
mV
PARAMETER
ICLK Input Buffer
SYMBOL
MIN
TYP
MAX
UNITS
0.4
V
COMMENTS
Low Input Level
VILCK
High Input Level
Input Leakage
(All I and IS buffers except
pins with
pullups/pulldowns)
VIHCK
3.0
Low Input Leakage
IIL
-10
+10
µA
VIN = 0
High Input Leakage
IP Type Buffers
IIH
-10
+10
µA
VIN = VCC
Input Current
ID Type Buffers
IIL
-150
µA
VIN = 0
Input Current
I/04 Type Buffer
IIH
+150
µA
VIN = VCC
Low Output Level
VOL
0.4
V
IOL = 4 mA
High Output Level
VOH
2.4
V
IOH = -2 mA
Output Leakage
I/024 Type Buffer
IOL
-10
+10
µA
VIN = 0 to VCC
Low Output Level
VOL
0.5
V
IOL = 24 mA
High Output Level
VOH
2.4
V
IOH = -12 mA
Output Leakage
024 Type Buffer
IOL
-10
+10
µA
VIN = 0 to VCC
Low Output Level
VOL
0.5
V
IOL = 24 mA
High Output Level
VOH
2.4
V
IOH = -12 mA
Output Leakage
04 Type Buffer
IOL
-10
+10
µA
VIN = 0 to VCC
Low Output Level
VOL
0.4
V
IOL = 4 mA
High Output Level
VOH
2.4
V
IOH = -2 mA
Output Leakage
IOL
-10
µA
VIN = 0 to VCC
V
-75
+75
+10
112
PARAMETER
OD16 Type Buffer
SYMBOL
MIN
Low Output Level
VOL
Output Leakage
OD162 Type Buffer
IOL
Low Output Level
VOL
High Output Level
VOH
2.4
Output Leakage
OD24 Type Buffer
IOL
-10
Low Output Level
VOL
Output Leakage
Supply Current Active
IOL
ICC
Supply Current Standby
TYP
-10
-10
60
ICSBY
MAX
UNITS
0.5
V
IOL = 16 mA
+10
µA
VIN = 0 to VCC
0.5
V
IOL = 16 mA
V
IOH = -2 mA
+10
µA
VIN = 0 to VCC
0.5
V
IOL = 24 mA
+10
95
µA
mA
8
COMMENTS
VIN = 0 to VCC
All outputs open
mA
CAPACITANCE TA = 25oC; fc = 1MHz; VCC = 5V
PARAMETER
Clock Input Capacitance
SYMBOL
CIN
Input Capacitance
Output Capacitance
CIN
COUT
MIN
LIMITS
TYP
MAX
20
10
20
113
UNIT
pF
pF
pF
TEST CONDITION
All pins except pin
under test tied to AC
ground
PARAMETER
MIN
10BASE-T
Receiver Threshold Voltage
Receiver Squelch
Receiver Common Mode Range
Transmitter Output: Voltage
Source Resistance
Transmitter Output DC Offset
Transmitter Backswing Voltage to Idle
Differential Input Voltage
300
0
±2
TYP
100
400
±2.5
±0.585
MAX
585
VDD
±3
10
50
100
±3
UNITS
mV
mV
V
ohms
mV
mV
V
AUI
Receiver Threshold Voltage
Receiver Squelch
Receiver Common Mode Range
Transmitter Output Voltage (R=78Ω)
Transmitter Backswing Voltage to Idle
Input Differential Voltage
Output Short Circuit (to VCC or GND) Current
Differential Idle Voltage (measured 8.0 µs
after last positive transition of data frame)
180
0
±0.45
±0.3
CAPACITIVE LOAD ON OUTPUTS
nIOCS16, IOCHRDY
INTRO-INTR3
All other outputs
240 pF
120 pF
45 pF
114
60
240
±0.85
300
VDD
±1.2
100
±1.2
±150
±40
mV
mV
V
mV
V
mV
mV
TIMING DIAGRAMS
t1
t2
A[5:0], nREG
0 min
t3
nCE1
nOE
t4
30 max
t5
t6
5 max
D[15:0]
DATA VALID
t1
t2
t3
t4
t5
t6
Parameter
Address Access Time
nREG Access Time
nCE1 Access Time
nOE Access Time
Output Disable Time from
nCE1 high
Output disable Time from nOE
high
Min
Typ
Max
300
300
300
150
100
Units
ns
ns
ns
ns
ns
100
ns
NOTE: Applies only when nWAIT is asserted by the LAN91C95.
FIGURE 18 - PCMCIA MEMORY READ TIMING
115
250 min
A[5:0], nREG
0 min
t4
20 min
nCE1
t3
nOE
t1
t7
t2
nWE
t6
t5
D[15:0 (Din)]
Parameter
t1
t2
t3
t4
t5
t6
t7
Min
nWE Pulse Width
Address/nREG Setup Time to
nWE Low
Address/nREG Setup Time to
nWE High
nCE1 Low to nWE High Setup
Time
Data to nWE High Setup Time
Data Hold Time from nWE High
Write Recovery Time (Address,
nREG Hold from nWE High)
Typ
Max
ns
ns
180
ns
180
ns
80
30
30
ns
ns
ns
NOTE: Minimum write pulse width must be met whether or not nWAIT is
asserted by the LAN91C95
FIGURE 19 - PCMCIA MEMORY WRITE TIMING
116
Units
150
30
A[15:0]
t18
nMCS
t15
t5
t3
nREG
t10
t17
t19
t2
t9
nCE
t20
t7
t6
t4
t16
nIORD
t1
t11
nINPACK
t8
t36
nIOIS16
t12
t13
t14
D[15::0]
FIGURE 20 - I/O READ TIMING
(Table on the following page)
117
t1
t2
t3
t4
t5
t6
t7
t8
t9
t10
t11
t12
t13
t14
t36
t15
t16
t17
t18
t19
t20
PARAMETER
Address setup before nIORD low
nCEI, nCE2 setup before nIORD low
nREG setup before nIORD low
nIORD low width
Address hold from nIORD high
nCE1, nCE2 hold following nIORD high
nREG hold following nIORD high
Address valid to nINPACK low
nCE1, nCE2 low to nINPACK low
nREG low to nINPACK low
nIORD low to nINPACK low
Address valid to nIOIs16 valid
nIORD low to data valid
Data hold following nIORD
nIOIS16 delay from address
Address valid to nMCS low
nCE1 low to nMCS low
nREG low to nMCS low
Address invalid to nMCS high
nCE1 high to nMCS high
nREG high to nMCS high
118
MIN
70
5
5
165
20
20
0
TYP
MAX
115
50
50
45
35
100
0
35
20
40
40
100
40
40
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
A[15:0]
nMCS
t33
t30
t25
t23
nREG
t35
t27
t32
t34
t22
nCE1
nCE2
t26
t31
t24
nIOWR
t21
t36
nIOIS16
t28
t29
D[15::0]
FIGURE 21 - (I/O WRITE TIMING)
(Table on the following page)
119
t21
t22
t23
t24
t25
t26
t27
t28
t29
t30
t31
t32
t33
t34
t35
t36
PARAMETER
Address setup before nIOWR low
nCE1, nCE2 setup before nIOWR low
nREG setup before nIOWR low
nIOWR low width
Address hold from nIOWR high
nCE1, nCE2, hold following nIOWR high
nREG hold following nIOWR high
Address valid to nIOIS16 valid
Data hold following nIOWR
Address valid to nMCS low
nCE1 low to nMCS low
nREG low to nMCS low
Address invalid to nMCS high
nCE1 high to nMCS high
nREG high to nMCS high
nIOIS16 delay from address
120
MIN
70
5
5
165
20
20
0
TYP
MAX
35
30
100
40
40
100
40
40
35
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
t60
A0-9,A15
t63
t60
valid
t61
valid
t62
nREG
t64
nCE1
t57
nWE
nOE
t59
t65
t58
D0-7
valid
t57
t58
t59
t60
t61
t62
t63
t64
t65
valid
Parameter
min
Write Data Setup to nWE Rising
Write Data Hold after nWE Rising
nOE Low to Valid Data
Address, nREG Setup to nWE Active
Address, nREG Hold after nOE Inactive
Address, nREG Setup to nOE Active
Address, nREG Hold after Control Inactive
nCE1 Setup to nWE Rising
nCE1 Low to Valid Data
30
9
typ
max
40
25
15
25
15
60
0
50
units
ns
ns
ns
ns
ns
ns
ns
ns
ns
FIGURE 22 - CARD CONFIGURATION REGISTERS - READ/WRITE PCMCIA MODE (A15=1)
121
t51
A0-9,A15
t52
valid
t48
t20
nREG
t49
t50
nCE1,nCE
t53
nIORD
t47
D0-15
valid
t46
t46
nINPAC
Parameter
t46
t47
t48
t20
t49
t50
t51
t52
t53
min
nIORD Delay to
nREG Low to Control
nCE1,nCE2 Setup to Control
Cycle Time (No Wait
nREG Hold after Control
nCE1,nCE2 Hold after Control
Address Setup to Control
Address Hold after Control
nIORD Active to Data
typ
0
5
5
185
0
15
25
15
0
FIGURE 23 - PCMCIA CONSECUTIVE READ CYCLES
122
max
units
35
ns
ns
ns
ns
ns
ns
ns
ns
ns
40
t51
A0-9,A15
t52
valid
t47
t49
nREG
t48
t50
nCE1,nCE2
t20
t54
t55
nIOWR
D0-15
valid
Parameter
t47
t48
t49
t50
t51
t52
t20
t54
t55
min
nREG Low Setup to Control Active
nCE1,nCE2 Setup to Control Active
nREG Hold after Control Inactive
nCE1,nCE2 Hold after Control Inactive
Address Setup to Control Active
Address Hold after Control Inactive
Cycle Time (No Wait States)
Write Data Setup to nIOWR Rising
Write Data Hold after nIOWR Rising
typ
max
5
5
0
15
25
15
185
30
9
FIGURE 24 - CONSECUTIVE PCMCIA WRITE CYCLES
123
units
ns
ns
ns
ns
ns
ns
ns
ns
ns
A0-9,A15
valid
valid
nREG
nCE1
t67
t67
t67
t67
t67
t67
t67
t67
t67
t67
t67
t67
nFCS
nWE
t66
t66
nFWE
nOE
Parameter
min
typ
max
units
t66
nWE to nFWE Delay
0
20
ns
t67
Address, nREG, nCE1 Delay to nFCS
0
25
ns
FIGURE 25 - PCMCIA ATTRIBUTE MEMORY READ/WRITE (A15=0)
124
nMPWDN]
MRINGOUTB
t2
t1
t1
t2
Parameter
MRINGOUTB Pulse Entering
Powerdown
MRINGOUTB Pulse Exiting
Powerdown
Min
Typ
Max
7.5
Units
ms
7.5
ms
FIGURE 26 - RINGOUT FOR L39/C39 ROCKWELL MODEMS ENTERING/EXITING POWERDOWN
125
A0-15
AEN, nSBHE
VALID ADDRESS
VALID ADDRESS
t4
t15
nIOCS16
t3
t20
nIORD
t5
t6
VALID DATA
OUT
D0-15
t3
t4
t5
t6
t15
t20
Z
VALID DATA
OUT
Parameter
min
Address, nSBHE, AEN Setup to Control Active
Address, nSBHE, AEN Hold after Control
Inactive
nIORD Low to Valid Data
nIORD High to Data Floating
A4-A15, AEN Low, BALE High to nIOCS16
Low
Cycle time*
25
20
typ
max
units
ns
ns
40
30
25
185
Z
ns
ns
ns
ns
BALE Tied High
IOCHRDY not used - t20 has to be met
*Note: The cycle time is defined only for consecutive accesses to the Data Register. These values assume
that IOCHRDY is not used.
FIGURE 27 - ISA CONSECUTIVE READ CYCLES
126
A0-15
AEN, nSBHE
VALID ADDRESS
VALID ADDRESS
t4
t15
nIOCS16
t3
t20
nIOWR
t8
t7
VALID DATA IN
D0-15
VALID DATA
Parameter
t3
t4
t7
t8
t15
t20
min
Address, nSBHE, AEN Setup to Control Active
Address, nSBHE, AEN Hold after Control
Inactive
Data Setup to nIOWR Rising
Data Hold after nIOWR Rising
A4-A15, AEN Low, BALE High to nIOCS16
Low
Cycle time*
typ
max
units
25
20
ns
ns
30
9
ns
ns
ns
25
185
ns
BALE Tied High
IOCHRDY not used - t20 has to be met
*Note: The cycle time is defined only for consecutive accesses to the Data Register. These values assume
that IOCHRDY is not used.
FIGURE 28 - ISA CONSECUTIVE WRITE CYCLES
127
A0-15
AEN,
nSBHE
VALID ADDRESS
VALID ADDRESS
nIOCS16
t20
nIORD
nIOWR
t9
Z
Z
t10
IOCHRDY
D0-D15
Z
VALID DATA
Parameter
t9
t10
t20
Z
VALID DATA
min
Control Active to IOCHRDY Low
IOCHRDY Low Pulse Width*
Cycle time**
100
185
typ
max
units
15
150
ns
ns
ns
*Note: Assuming NO WAIT ST = 0 in configuration register and cycle time observed.
**Note: The cycle time is defined only for accesses to the Data Register as follows:
For Data Register Read - From nIORD falling to next nIORD falling
For Data Register Write - From nIOWR rising to next nIOWR rising
FIGURE 29 - ISA CONSECUTIVE READ AND WRITE CYCLES
128
Z
A0-15
(ISA)
AEN,
nSBHE
VALID ADDRESS
nIOCS16
nIORD
t9
Z
IOCHRDY
t18
Z
t19
VALID DATA
OUT
D0-D15
Parameter
min
typ
max
units
t9
Control Active to IOCHRDY Low
15
ns
t18
IOCHRDY Width when Data is Unavailable at
Data Register
Valid Data to IOCHRDY Inactive
575
225
ns
ns
t19
IOCHRDY is used instead of meeting t20 and t43.
"No Wait St' bit is 1 - IOCHRDY only negated if needed and only for Data Register access.
FIGURE 30 - DATA REGISTER SPECIAL READ ACCESS
129
A0-15
VALID ADDRESS
(ISA)
AEN,
nSBHE
nIOCS16
nIOWR
t9
IOCHRDY
t18
Z
D0-D15
Z
VALID DATA IN
Parameter
min
typ
max
units
t9
Control Active to IOCHRDY Low
15
ns
t18
IOCHRDY Width when Data Register is Full
425
ns
IOCHRDY is used instead of meeting t20 and t44.
'No Wait St' bit is 1 - IOCHRDY only negated if needed and only for Data Register access.
FIGURE 31 - DATA REGISTER SPECIAL WRITE ACCESS
130
A0-15
(ISA)
AEN
VALID ADDRESS
VALID ADDRESS
t3
nIOWR
t3
nIORD
t7
t8
t5
Z
D0-7
Parameter
t3
t5
t7
t8
Z
VALID DATA OUT
VALID DATA IN
min
Address, nSBHE, AEN Setup to Control Active
nIORD Low to Valid Data
Data Setup to nIOWR Rising
Data Hold after nIOWR Rising
typ
max
25
40
30
9
units
ns
ns
ns
ns
FIGURE 32 - 8 BIT MODE REGISTER CYCLES
A0-19
ADDRESS VALID
t3
t4
nMEMRD
Z
D0-15
Parameter
t3
t4
t16
t17
min
Address Setup to Control Active
Address Hold after Control Inactive
nMEMRD Low to nROM Low
nMEMRD High to nROM High
typ
25
20
0
0
BALE tied high
FIGURE 33 - EXTERNAL ROM READ ACCESS
131
max
units
25
30
ns
ns
ns
ns
t4
AEN
A0-15,
nSBHE
VALID
t1
BALE
t2
t15
nIOCS16
t3
nIORD
nIOWR
Parameter
min
typ
max
units
t1
Address, nSBHE Setup to BALE Falling
20
ns
t2
Address, nSBHE Hold after BALE Falling
20
ns
t3
t4
Address, nSBHE, AEN Setup to Control Active
AEN Hold after Control Inactive
25
20
ns
ns
t15
A4-A15, AEN Low, BALE High to nIOCS16 Low
25
t4 not needed. nIOCS16 not relevant in 8-bit mode.
FIGURE 34 - ISA REGISTER ACCESS WHEN USING BALE
132
ns
A0-19
VALID
t1
t2
BALE
t3
nMEMRD
t16
t17
nROM
Parameter
min
typ
max
units
t1
Address Setup to BALE Falling
20
ns
t2
Address Hold after BALE Falling
20
ns
t3
Address Setup to Control Active
25
ns
t16
nMEMRD Low to nROM Low
25
ns
t17
nMEMRD High to nROM High
30
ns
FIGURE 35 - EXTERNAL ROM READ ACCESS USING BALE
133
EESK
EEDO
EEDI
EECS
t21
t21
Parameter
t21
min
EESK Falling to EEDO, EECS Changing
0
9346 is typically the serial EEPROM used.
FIGURE 36 - EEPROM READ
134
typ
max
units
100
ns
EESK
EEDO
EEDI
EECS
t21
t21
Parameter
t21
min
EESK Falling to EEDO, EECS Changing
9346 is typically the serial EEPROM used.
FIGURE 37 - EEPROM WRITE
135
typ
max
units
100
ns
ADDRESS
POINTER
REGISTER
DATA
REGISTER
nIOWR
t44
nIORD
IOCHRDY/
nWAIT (Z)
Parameter
t44
min
Pointer Register Reloaded to a Word of Data
Prefetched into Data Register
typ
max
2 * t20
units
ns
Note: If t44 is not met, IOCHRDY will be negated for the required time. This parameter can be ignored if
IOCHRDY is connected to the system.
FIGURE 38 - MEMORY READ TIMING
ADDRESS
DATA
REGISTER
POINTER
REGISTER
nIOWR
t45
Parameter
t45
min
Last Access to Data Register to Pointer
Reloaded
typ
2 * t20
FIGURE 39 - MEMORY WRITE TIMING
136
max
units
ns
nTXEN
TXD
TXCLK
t22
t22
Parameter
t22
min
typ
0
TXD, nTXEN Delay from TXCLK Falling
max
units
40
ns
FIGURE 40 - EXTERNAL ENDEC INTERFACE - START OF TRANSMIT
t23
t24
RXD
RXCLK
nCRS
t23
Parameter
t23
t24
min
10
30
nCRS, RXD Setup to RXCLK Falling
nCRS, RXD Hold after RXCLK Falling
typ
max
units
ns
ns
FIGURE 41 - EXTERNAL ENDEC INTERFACE - RECEIVE DATA (RXD SAMPLED BY FALLING
RXCLK)
137
TPETXP
t31
t31
TPETXN
t32
t32
TPETXDN
t33
t33
TPETXDP
TWISTED PAIR DRIVERS
TXP
t34
t34
TXN
AUI DRIVERS
Parameter
t31
t32
t33
t34
min
TPETXP to TPETXN Skew
TPETXP(N) to TPETXDP(N) Delay
TPETXDN to TPETXDP Skew
TXP to TXN Skew
-1
47
-1
-1.5
typ
max
units
+1
53
+1
1.5
ns
ns
ns
ns
FIGURE 42 - DIFFERENTIAL OUTPUT SIGNAL TIMING (10BASE-T AND AUI)
138
1
0
1
0
1
0
1
0
1
0
1
0
1
0
RECP
RECN
t35
first bit decoded
nCRS
(internal)
t36
1
0
1
0
1
0
TPERXP(N)
t37
nCRS
(internal)
first bit decoded
t38
Parameter
t35
t36
t37
t38
min
typ
max
units
15
Noise Pulse Width Reject (AUI)
Carrier Sense Turn On Delay (AUI)
50
Noise Sense Pulse Width Reject (10BASE-T) 15
450
Carrier Sense Turn On Delay (10BASE-T)
25
70
25
500
30
100
30
550
ns
ns
ns
ns
FIGURE 43 - RECEIVE TIMING - START OF FRAME (AUI AND 10BASE-T)
139
last bit
b
a
1/0
TPERXP
TPERXN
RECP
RECN
t39
nCRS
(internal)
Parameter
t39
min
200
Receiver Turn Off Delay
typ
max
units
300
ns
FIGURE 44 - RECEIVE TIMING - END OF FRAME (AUI AND 10BASE-T)
140
t40
t41
TPETXP
TPETXN
last bit
b
a
1/0
TXP
TXN
Parameter
min
t40
Transmit Output High to Idle in Half-Step Mode
t41
Transmit Output High before Idle in Half-Step
Mode
typ
max
units
800
ns
200
FIGURE 45 - TRANSMIT TIMING - END OF FRAME (AUI AND 10BASE-T)
141
ns
COLLP
COLLN
t42
t43
COL
(internal)
Parameter
min
typ
max
units
t42
Collision Turn On Delay
50
ns
t43
Collision Turn Off Delay
350
ns
FIGURE 46 - COLLISION TIMING (AUI)
142
A2 A1
He
E
Y
Hd D
L1
c
e
0.08(0.003) M
b
0
GAGE PLANE
0.25
L
MILLIMETER
INCH
SYMBOL
MIN. NOM. MAX.
MIN.
NOM.
MAX.
A1
0.05
0.10
0.15
0.002 0.004
0.006
A2
b
c
D
0.95
1.00
1.05
0.037 0.039
0.041
0.13
0.18
0.23
0.005 0.007
0.009
0.20
E
e
Hd
He
L
0.09
0.004
0.008
13.90 14.00 14.10
0.547 0.551
0.555
13.90 14.00 14.10
0.547 0.551
0.555
0.40
15.90 16.00 16.10
0.626 0.630
0.634
15.90 16.00 16.10
0.626 0.630
0.634
0.45
0.018 0.024
0.030
L1
Y
0
0.016
0.60
0.75
1.00
0.039
0.08
0
7
0.003
0
7
FIGURE 47 - TQFP PACKAGE OUTLINE
143
LAN91C95 ERRATA SHEET
PAGE
24
35-40
63
112
SECTION/FIGURE/ENTRY
Modem Interface
Tables 6A - 8B
Refer to table/STSCHG_SLCT
Paragraph
DC Electrical Characteristics
CORRECTION
Section added to data sheet
Tables added to data sheet
See Italicized Text
DATE
REVISED
7/4/97
7/4/97
7/4/97
See Italicized Text
7/4/97
©1997 STANDARD MICROSYSTEMS CORPORATION (SMSC)
Circuit diagrams utilizing SMSC products are included as a means of illustrating typical applications; consequently complete
information sufficient for construction purposes is not necessarily given. The information has been carefully checked and is believed
to be entirely reliable. However, no responsibility is assumed for inaccuracies. Furthermore, such information does not convey to the
purchaser of the semiconductor devices described any licenses under the patent rights of SMSC or others. SMSC reserves the right
to make changes at any time in order to improve design and supply the best product possible. SMSC products are not designed,
intended, authorized or warranted for use in any life support or other application where product failure could cause or contribute to
personal injury or severe property damage. Any and all such uses without prior written approval of an Officer of SMSC and further
testing and/or modification will be fully at the risk of the customer.
LAN91C95 Rev. 07/04/97