Maxim DS80C400 Network microcontroller Datasheet

19-4658; Rev 7; 6/09
EVALUATION KIT AVAILABLE
DS80C400
Network Microcontroller
www.maxim-ic.com
GENERAL DESCRIPTION
FEATURES
The DS80C400 network microcontroller offers the highest
integration available in an 8051 device. Peripherals include
a 10/100 Ethernet MAC, three serial ports, a CAN 2.0B
®
controller, 1-Wire Master, and 64 I/O pins.

To enable access to the network, a full applicationaccessible TCP IPv4/6 network stack and OS are provided
in the ROM. The network stack supports up to 32
simultaneous TCP connections and can transfer up to
5Mbps through the Ethernet MAC. Its maximum systemclock frequency of 75MHz results in a minimum instruction
cycle time of 54ns. Access to large program or data
memory areas is simplified with a 24-bit addressing
scheme that supports up to 16MB of contiguous memory.

To accelerate data transfers between the microcontroller
and memory, the DS80C400 provides four data pointers,
each of which can be configured to automatically increment
or decrement upon execution of certain data pointer-related
instructions. The DS80C400’s hardware math accelerator
further increases the speed of 32-bit and 16-bit multiply
and divide operations as well as high-speed shift,
normalization, and accumulate functions.

The High-Speed Microcontroller User’s Guide and the High-Speed
Microcontroller User’s Guide: Network Microcontroller Supplement
should be used in conjunction with this data sheet. Download
both at: www.maxim-ic.com/user_guides.

APPLICATIONS
Industrial Control/Automation
Environmental Monitoring
Network Sensors
Data Converters (Serialto-Ethernet, CAN-toEthernet)
Remote Data Collection
Equipment
Vending
Home/Office Automation

Transaction/Payment
Terminals
ORDERING INFORMATION
PART
TEMP RANGE
PIN-PACKAGE
DS80C400-FNY
-40°C to +85°C
100 LQFP
DS80C400-FNY+
-40°C to +85°C
100 LQFP

+Denotes a lead(Pb)-free/RoHS-compliant package.
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
Magic Packet is a registered trademark of Advanced Micro Devices, Inc.
DeviceNet is a trademark of Open DeviceNet Vendor Association, Inc.
High-Performance Architecture
Single 8051 Instruction Cycle in 54ns
DC to 75MHz Clock Rate
Flat 16MB Address Space
Four Data Pointers with Auto-Increment/
Decrement and Select-Accelerate Data Movement
16/32-Bit Math Accelerator
Multitiered Networking and I/O
10/100 Ethernet Media Access Controller (MAC)
CAN 2.0B Controller
1-Wire Net Controller
Three Full-Duplex Hardware Serial Ports
Up to Eight Bidirectional 8-Bit Ports (64 Digital I/O
Pins)
Robust ROM Firmware
Supports Network Boot Over Ethernet Using DHCP
and TFTP
Full, Application-Accessible TCP/IP Network Stack
Supports IPv4 and IPv6
Implements UDP, TCP, DHCP, ICMP, and IGMP
Preemptive, Priority-Based Task Scheduler
MAC Address can Optionally be Acquired from IEEERegistered DS2502-E48
10/100 Ethernet MAC
Flexible IEEE 802.3 MII (10/100Mbps) and ENDEC
(10Mbps) Interfaces Allow Selection of PHY
Low-Power Operation
®
Ultra-Low-Power Sleep Mode with Magic Packet
and Wake-Up Frame Detection
8kB On-Chip Tx/Rx Packet Data Memory with Buffer
Control Unit Reduces Load on CPU
Half- or Full-Duplex Operation with Flow Control
Multicast/Broadcast Address Filtering with VLAN
Support
Full-Function CAN 2.0B Controller
15 Message Centers
Supports Standard (11-Bit) and Extended (29-Bit)
Identifiers and Global Masks
Media Byte Filtering to Support DeviceNet™, SDS, and
Higher Layer CAN Protocols
Auto-Baud Mode and SIESTA Low-Power Mode
Integrated Primary System Logic
16 Total Interrupt Sources with Six External
Four 16-Bit Timer/Counters
2x/4x Clock Multiplier Reduces Electromagnetic
Interference (EMI)
Programmable Watchdog Timer
Oscillator-Fail Detection
Programmable IrDA Clock
Features continued on page 32.
Pin Configuration appears at end of data sheet.
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata.
1 of 97
DS80C400 Network Microcontroller
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Input Pin Relative to Ground……………....………………………………………..-0.5V to +5.5V
Voltage Range on Any Output Pin Relative to Ground……....……………………………………..-0.5V to (VCC3 + 0.5V)
Voltage Range on VCC3 Relative to Ground…………………………………………………………………..-0.5V to +3.6V
Voltage Range on VCC1 Relative to Ground…………………………………………………………………..-0.3V to +2.0V
Operating Temperature Range………………………………………………………………………………..-40°C to +85°C
Junction Temperature……………………………………………………………………………………………..+150°C max
Storage Temperature Range………………………………………………………………………………...-55°C to +160°C
Soldering Temperature………………………………………………………….See IPC/JEDEC J-STD-020 Specification
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is
not implied. Exposure to absolute maximum rating conditions for extended periods can affect device reliability.
DC ELECTRICAL CHARACTERISTICS (Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V ±10%, TA = -40°C to +85°C.)
PARAMETER
VCC1
VCC3
Supply Voltage (VCC3) (Note 2)
Power-Fail Warning (VCC3) (Note 3)
Power-Fail Reset Voltage (VCC3) (Note 3)
Active Mode Current (VCC3) (Note 4)
Idle Mode Current (VCC3) (Note 4)
Stop Mode Current (VCC3) (Not 4)
Stop Mode Current, Bandgap Enabled (VCC3) (Note 4)
Supply Voltage (VCC1) (Note 2)
Power-Fail Warning (VCC1) (Note 5)
Power-Fail Reset Voltage (VCC1) (Note 5)
Active Mode Current (VCC1) (Note 4)
Idle Mode Current (VCC1) (Note 4)
Stop Mode Current (VCC1) (Note 4)
Stop Mode Current, Bandgap Enabled (VCC1) (Note 4)
Input Low Level
Input Low Level for XTAL1, RST, OW
Input High Level
Input High Level for XTAL1, RST, OW
Output Low Current for Port 1, 3–7 at VOL = 0.4V
Output Low Current for Port 0, 2, TX_EN, TXD[3:0], MDC, MDIO,
RSTOL, ALE, PSEN, and Ports 3–7 (when used as any of the following:
A21–A0, WR, RD, CE0-7, PCE0-3) at VOL = 0.4V (Note 6)
Output Low Current for OW, OWSTP at VOL= 0.4V
Output High Current for Port 1, 3–7 at VOH = VCC3 - 0.4V (Note 7)
Output High Current for Port 1, 3–7 at VOH= VCC3 - 0.4V (Note 8)
Output High Current for Port 0, 2, TX_EN, TXD[3:0], MDC, MDIO,
RSTOL, ALE, PSEN, and Ports 3–7 (when used as any of the following:
A21–A0, WR, RD, CE0-7, PCE0-3) at VOH = VCC3 - 0.4V (Notes 6, 9)
Input Low Current for Port 1–7 at 0.4V (Note 10)
Logic 1-to-0 Transition Current for Port 1, 3–7 (Note 11)
Input Leakage Current, Port 0 Bus Mode, VIL = 0.8V (Note 12)
Input Leakage Current, Port 0 Bus Mode, VIH = 2.0V (Note 12)
Input Leakage Current, Input Mode (Note 13)
RST Pulldown Resistance
SYMBOL
MIN
TYP
MAX
UNITS
VCC3
VPFW3
VRST3
ICC3
IIDLE3
ISTOP3
ISPBG3
VCC1
VPFW1
VRST1
ICC1
IIDLE1
ISTOP1
ISPBG1
VIL1
VIL2
VIH1
VIH2
IOL1
3.0
2.85
2.76
3.3
3.00
2.90
16
7
1
100
1.8
1.60
1.55
27
20
0.2
0.2
3.6
3.15
3.05
35
15
10
150
1.98
1.68
1.63
50
40
10
10
0.8
1.0
2.0
2.4
6
10
V
V
V
mA
mA
A
A
V
V
V
mA
mA
mA
mA
V
V
V
V
mA
IOL2
12
20
mA
IOL3
IOH1
IOH2
10
16
-75
-8
-50
-4
mA
A
mA
-16
-8
mA
-20
-400
50
-50
0
100
-10
A
A
A
A
A
k
1.62
1.52
1.47
IOH3
IIL
ITL
ITH0
ITL0
IL
RRST
-50
-650
20
-200
-15
50
200
-20
15
200
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: The user should note that this part is tested and guaranteed to operate down to VCC3 = 3.0V and VCC1 = 1.62V, while the reset
thresholds for those supplies, VRST3 and VRST1 respectively, may be above or below those points. When the reset threshold for a given
supply is greater than the guaranteed minimum operating voltage, that reset threshold should be considered the minimum operating
point since execution ceases once the part enters the reset state. When the reset threshold for a given supply is lower than the
guaranteed minimum operating voltage, there exists a range of voltages for either supply, (VRST3 < VCC3 < 1.62V) or (VRST1 < VCC1 <
3.0V), where the processor’s operation is not guaranteed, and the reset trip point has not been reached. This should not be an issue in
2 of 97
DS80C400 Network Microcontroller
most applications, but should be considered when proper operation must be maintained at all times. For these applications, it may be
desirable to use a more accurate external reset.
Note 3: While the specifications for VPFW3 and VRST3 overlap, the design of the hardware makes it such that this is not possible. Within the ranges
given, there is a guaranteed separation between these two voltages.
Note 4: Current measured with 75MHz clock source on XTAL1, VCC3 = 3.6V, VCC1 = 2.0V, EA and RST = 0V, Port0 = VCC3, all other pins
disconnected.
Note 5: While the specifications for VPFW1 and VRST1 overlap, the design of the hardware makes it such that this is not possible. Within the ranges
given, there will be a guaranteed separation between these two voltages.
Note 6: Certain pins exhibit stronger drive capability when being used to address external memory. These pins and associated memory
interface function (in parentheses) are as follows: Port 3.6-3.7 (WR, RD), Port 4 (CE0-3, A16-A19), Port 5.4-5.7 (PCE0-3), Port 6.0-6.5
(CE4-7, A20, A21), Port 7 (demultiplexed mode A0-A7).
Note 7: This measurement reflects the weak I/O pullup state that persists following the momentary strong 0 to 1 port pin drive (VOH2). This I/O
pin state can be achieved by applying RST = VCC3.
Note 8: The measurement reflects the momentary strong port pin drive during a 0-to-1 transition in I/O mode. During this period, a one shot
circuit drives the ports hard for two clock cycles. A weak pullup device (VOH1) remains in effect following the strong two-clock cycle
drive. If a port 4 or 6 pin is functioning in memory mode with pin state of 0 and the SFR bit contains a 1, changing the pin to an I/O
mode (by writing to P4CNT, for example) does not enable the two-cycle strong pullup.
Note 9: Port 3 pins 3.6 (WR) and 3.7(RD) have a stronger than normal pullup drive for only one system clock period following the transition of
either WR or RD from a 0 to a 1.
Note 10: This is the current required from an external circuit to hold a logic low level on an I/O pin while the corresponding port latch bit is set to
1. This is only the current required to hold the low level; transitions from 1 to 0 on an I/O pin also have to overcome the transition
current.
Note 11: Following the 0 to 1 one-shot timeout, ports in I/O mode source transition current when being pulled down externally. It reaches a
maximum at approximately 2V.
Note 12: During external addressing mode, weak latches are used to maintain the previously driven state on the pin until such time that the Port
0 pin is driven by an external memory source.
Note 13: The OW pin (when configured to output a 1) at VIN = 5.5V, EA, MUX, and all MII inputs (TXCLk, RXCLk, RX_DV, RX_ER, RXD[3:0],
CRS, COL, MDIO) at VIN = 3.6V.
AC ELECTRICAL CHARACTERISTICS (MULTIPLEXED ADDRESS/DATA BUS)
(Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V ±10%, TA = -40°C to +85°C.)
PARAMETER
External Crystal Frequency
Clock Mutliplier 2X Mode
Clock Multiplier 4X Mode
External Clock Oscillator Frequency
Clock Mutliplier 2X Mode
Clock Multiplier 4X Mode
ALE Pulse Width
Port 0 Instruction Address Valid to ALE Low
Address Hold After ALE Low
ALE Low to Valid Instruction In
ALE Low to PSEN Low
PSEN Pulse Width
PSEN Low to Valid Instruction In
Input Instruction Hold After PSEN
Input Instruction Float After PSEN
Port 0 Address to Valid Instruction In
Port 2, 4, 6 Address or Port 4 CE to Valid
Instruction In
PSEN Low to Address Float
8.3
21.0
VARIABLE CLOCK
MIN
MAX
4
40
16
37.5
11
18.75
DC
75
16
37.5
11
18.75
tCLCL + tCHCL - 5
tCHCL - 5
tCLCH - 2
2tCLCL + tCLCH - 19
tCLCH - 3
2tCLCL - 5
2tCLCL -17
0
tCLCL - 5
3tCLCL - 19
tAVIV2
27.7
3tCLCL + tCLCH - 19
ns
tPLAZ
0
0
ns
SYMBOL
75MHz
MIN
MAX
1 / tCLK
1 / tCLK
tLHLL
tAVLL
tLLAX
tLLIV
tLLPL
tPLPH
tPLIV
tPXIX
tAVIV0
15.0
1.7
4.7
14.3
3.7
21.7
9.7
0
UNITS
MHz
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: All parameters apply to both commercial and industrial temperature operation, unless otherwise noted.
Note 3: tCLCL, tCLCH, tCHCL are time periods associated with the internal system clock and are related to the external clock (tCLK) as defined in the
External Clock Oscillator (XTAL1) Characteristics table.
Note 4: The precalculated 75MHz MIN/MAX timing specifications assume an exact 50% duty cycle.
Note 5: All signals guaranteed with load capacitance of 80pF except Port 0, Port 2, ALE, PSEN, RD, and WR with 100pF. The following signals,
when configured for memory interface, are also characterized with 100pF loading: Port 4 (CE0-3, A16–A19), Port 5.4–5.7 ( PCE0-3),
Port 6.0–6.5 (CE4-7, A20, A21), Port 7 (demultiplexed mode A0–A7).
Note 6: For high-frequency operation, special attention should be paid to the float times of the interfaced memory devices so as to avoid bus
contention.
Note 7: References to the XTAL, XTAL1 or CLK signal in timing diagrams is to assist in determining the relative occurrence of events, not for
determing absolute signal timing with respect to the external clock.
3 of 97
DS80C400 Network Microcontroller
EXTERNAL CLOCK OSCILLATOR (XTAL1) CHARACTERISTICS
PARAMETER
SYMBOL
Clock Oscillator Period
tCLK
Clock Symmetry at 0.5 x VCC3
Clock Rise Time
Clock Fall Time
tCH
tCR
tCF
MIN
MAX
See External Clock
Oscillator Frequency
0.45 tCLK
0.55 tCLK
3
3
UNITS
ns
ns
ns
EXTERNAL CLOCK DRIVE
tCF
tCR
XTAL1
tCH
tCL
tCLK
SYSTEM CLOCK TIME PERIODS (tCLCL, tCHCL, tCLCH)
SYSTEM CLOCK SELECTION
4X/2X
1
0
X
X
CD1
0
0
1
1
SYSTEM CLOCK HIGH (tCHCL ) AND
SYSTEM CLOCK LOW (tCLCH)
MIN
MAX
0.45 (tCLK / 4)
0.55 (tCLK / 4)
0.45 (tCLK / 2)
0.55 (tCLK / 2)
0.45 tCLK
0.55 tCLK
0.45 (256 tCLK)
0.55 (256 tCLK)
SYSTEM CLOCK
PERIOD tCLCL
CD0
0
0
0
1
tCLK / 4
tCLK / 2
tCLK
256 tCLK
Note 1: Figure 20 shows a detailed description and illustration of the system clock selection.
Note 2: When an external clock oscillator is used in conjunction with the default system clock selection (CD1:CD0 = 10b), the
minimum/maximum system clock high (tCHCL) and system clock low (tCLCH) periods are directly related to clock oscillator duty cycle.
MOVX CHARACTERISTICS (MULTIPLEXED ADDRESS/DATA BUS) (Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V ±10%, TA = -40 C to +85°C.)
PARAMETER
SYMBOL
MOVX ALE Pulse Width
tLHLL2
Port 0 MOVX Address Valid
to ALE Low
tAVLL2
Port 0 MOVX Address Hold
after ALE Low
tLLAX2
and tLLAX3
RD Pulse Width (P3.7 or
PSEN)
tRLRH
WR Pulse Width (P3.6)
tWLWH
RD (P3.7 or PSEN) Low to
Valid Data In
Data Hold After RD (P3.7 or
PSEN) High
MIN
MAX
tCLCL + tCHCL - 5
2tCLCL - 5
6tCLCL - 5
tCHCL - 5
tCLCL - 6
5tCLCL - 6
tCLCH - 2
tCLCL - 2
5tCLCL - 2
2tCLCL - 5
(4 x CST) tCLCL - 3
2tCLCL - 5
(4 x CST) tCLCL - 3
tRHDX
ns
ns
ns
ns
ns
2tCLCL - 17
(4 x CST) tCLCL - 17
tRLDV
-2
UNITS
ns
ns
4 of 97
STRETCH VALUES
CST (MD2:0)
CST = 0
1 CST  3
4  CST  7
CST = 0
1 CST  3
4  CST  7
CST = 0
1 CST 3
4  CST  7
CST = 0
1  CST  7
CST = 0
1  CST  7
CST = 0
1  CST  7
DS80C400 Network Microcontroller
PARAMETER
SYMBOL
Data Float After RD (P3.7 or
PSEN) High
tRHDZ
ALE Low to Valid Data In
tLLDV
Port 0 Address to Valid Data
In
tAVDV0
Port 2, 4, 6 Address, Port 4
CE, or Port 5 PCE to Valid
Data In
tAVDV2
ALE Low to (RD or PSEN) or
WR Low
tLLWL
Port 0 Address to (RD or
PSEN) or WR Low
tAVWL0
Port 2, 4 Address, Port 4 CE,
Port 5 PCE, to (RD or PSEN)
or WR Low
tAVWL2
Data Valid to WR Transition
tQVWX
Data Hold After WR High
tWHQX
RD Low to Address Float
tRLAZ
MIN
MAX
tCLCH - 3
tCLCL - 3
5tCLCL - 3
tCLCL - 5
2tCLCL - 6
10tCLCL - 6
tCLCL + tCLCH - 5
2tCLCL + tCLCH - 5
10tCLCL + tCLCH - 5
0
tCLCL - 4
2CLCL - 7
6tCLCL - 7
tCLCL - 5
2tCLCL - 5
6tCLCL - 5
2tCLCL + tCLCH - 19
(4 x CST + 1) tCLCL - 19
(4 x CST + 5) tCLCL - 19
3tCLCL - 19
(4 x CST + 2)tCLCL - 19
(4 x CST + 10)tCLCL - 19
3tCLCL + tCLCH - 19
(4 x CST + 2)tCLCL + tCLCH 19
(4 x CST + 10)tCLCL + tCLCH 20
tCLCH + 6
tCLCL + 6
5tCLCL + 6
tWHLH
(RD or PSEN) or WR High to
Port 4 CE or Port 5 PCE
High
tWHLH2
ns
ns
ns
ns
STRETCH VALUES
CST (MD2:0)
CST = 0
1 CST  3
4  CST  7
CST = 0
1 CST  3
4  CST  7
CST = 0
1 CST  3
4  CST  7
CST = 0
1 CST  3
4  CST  7
ns
ns
ns
CST = 0
1  CST  3
4  CST  7
CST = 0
1  CST  3
4  CST  7
CST = 0
1  CST  3
4  CST  7
ns
ns
(Note 2)
0
(RD or PSEN) or WR High to
ALE
UNITS
tCLCL - 3
5tCLCL - 3
tCHCL -5
tCLCL + tCHCL - 5
5tCLCL + tCHCL - 5
7
tCLCL + 4
5tCLCL + 4
tCHCL + 13
tCLCL + tCHCL + 13
5tCLCL + tCHCL + 13
ns
ns
CST = 0
1  CST  3
4  CST  7
0 CST  7
CST = 0
1  CST  3
4  CST  7
CST = 0
1  CST  3
4  CST  7
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: For a MOVX read operation, on the falling edge of ALE, Port 0 is held by a weak latch until overdriven by external memory.
Note 3: All parameters apply to both commercial and industrial temperature operation, unless otherwise noted.
Note 4: CST is the stretch cycle value as determined by the MD2, MD1, and MD0 bits of the CKCON register. tCLCL , tCLCH , tCHCL are time
periods associated with the internal system clock and are related to the external clock. See the System Clock Time Periods table.
Note 5: All signals characterized with load capacitance of 80pF except Port 0, Port 2, ALE, PSEN, RD, and WR with 100pF. The following
signals, when configured for memory interface, are also characterized with 100pF loading: Port 4 (CE0-3, A16–A19), Port 5.4–5.7
(PCE0-3), Port 6.0–6.5 (CE4-7, A20, A21), Port 7 (demultiplexed mode A0–A7).
Note 6: References to the XTAL, XTAL1, or CLK signal in timing diagrams are to assist in determining the relative occurrence of events, not for
determing absolute signal timing with respect to the external clock.
5 of 97
DS80C400 Network Microcontroller
6 of 97
DS80C400 Network Microcontroller
7 of 97
DS80C400 Network Microcontroller
MULTIPLEXED, 2-CYCLE DATA MEMORY PCE0-3 READ
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
MULTIPLEXED, 2-CYCLE DATA MEMORY CE0-7 READ
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
8 of 97
A16 -A21
A16 -A21
DS80C400 Network Microcontroller
MULTIPLEXED, 2-CYCLE DATA MEMORY CE0-7 WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
MULTIPLEXED, 3-CYCLE DATA MEMORY PCE0-3 READ OR WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
9 of 97
A16 -A21
A16 -A21
DS80C400 Network Microcontroller
MULTIPLEXED, 3-CYCLE DATA MEMORY CE0-7 READ
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
MULTIPLEXED, 3-CYCLE DATA MEMORY CE0-7 WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
10 of 97
A16 -A21
A16 -A21
DS80C400 Network Microcontroller
MULTIPLEXED, 9-CYCLE DATA MEMORY PCE0-3 READ OR WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
MULTIPLEXED, 9-CYCLE DATA MEMORY CE0-7 READ
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6
ADDRESS
A16 -A21
A16 -A21
A16 -A21
11 of 97
A16 -A21
DS80C400 Network Microcontroller
MULTIPLEXED, 9-CYCLE DATA MEMORY CE0-7 WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6
ADDRESS
A16 -A21
A16 -A21
A16 -A21
12 of 97
A16 -A21
DS80C400 Network Microcontroller
ELECTRICAL CHARACTERISTICS (NONMULTIPLEXED ADDRESS/DATA BUS)
(Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V ±10%, TA = -40°C to +85°C.)
PARAMETER
External Crystal Frequency
Clock Mutliplier 2X Mode
Clock Multiplier 4X Mode
External Oscillator Frequency
Clock Mutliplier 2X Mode
Clock Multiplier 4X Mode
PSEN Pulse Width
PSEN Low to Valid Instruction In
Input Instruction Hold After PSEN
SYMBOL
75MHz
MIN
MAX
1 / tCLK
1 / tCLK
tPLPH
tPLIV
tPXIX
21.7
9.7
0
Input Instruction Float After PSEN
tPXIZ
Port 7 Address to Valid Instruction In
Port 2, 4, 6 Address or Port 4 CE to Valid
Instruction In
tAVIV1
21.0
tAVIV2
27.7
VARIABLE CLOCK
MIN
MAX
4
40
16
37.5
11
18.75
DC
75
16
37.5
11
18.75
2tCLCL - 5
2tCLCL - 17
0
See MOVX
Characteristics
3tCLCL - 19
3tCLCL + tCLCH - 19
UNITS
MHz
MHz
ns
ns
ns
ns
ns
ns
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: All parameters apply to both commercial and industrial temperature operation, unless otherwise noted.
Note 3: tCLCL, tCLCH, tCHCL are time periods associated with the internal system clock and are related to the external clock (tCLK) as defined in the
the System Clock Time Periods table.
Note 4: The precalculated 75MHz min/max timing specifications assume an exact 50% duty cycle.
Note 5: All signals characterized with load capacitance of 80pF except Port 0, Port 2, ALE, PSEN, RD, and WR with 100pF. The following
signals, when configured for memory interface, are also characterized with 100pF loading: Port 4 (CE0-3, A16–A19), Port 5.4–5.7
(PCE0-3), Port 6.0–6.5 (CE4-7, A20, A21), Port 7 (demultiplexed mode A0–A7).
Note 6: References to the XTAL, XTAL1, or CLK signal in timing diagrams is to assist in determining the relative occurrence of events, not for
determing absolute signal timing with respect to the external clock.
13 of 97
DS80C400 Network Microcontroller
MOVX CHARACTERISTICS (NONMULTIPLEXED ADDRESS/DATA BUS) (Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V +±10%, TA = -40°C to +85°C.)
PARAMETER
SYMBOL
Input Instruction Float After PSEN
tPXIZ
PSEN High to Data Address, Port 4 CE,
Port 5 PCE Valid
tPHAV
RD Pulse Width (P3.7 or PSEN)
tRLRH
WR Pulse Width (P3.6)
tWLWH
RD (P3.7 or PSEN) Low to Valid Data In
tRLDV
Data Hold After RD (P3.7 or PSEN) High
tRHDX
Data Float After RD (P3.7 or PSEN) High
tRHDZ
PSEN High to WR Low
tPHWL
PSEN High to (RD or PSEN) Low
tPHRL
Port 7 Address to Valid Data In
Port 2, 4, 6 Address, Port 4 CE or Port 5
PCE to Valid Data In
MIN
Port 2, 4, 6 Address, Port 4 CE or Port 5
PCE to (RD or PSEN) or WR Low
tAVWL2
Data Valid to WR Transition
tQVWX
Data Hold After WR High
tWHQX
(RD or PSEN) or WR High to Port 4 CE
or Port 5 PCE High
tWHCEH
2tCLCL - 5
3tCLCL - 5
11tCLCL - 5
ns
ns
ns
2tCLCL - 17
(4 x CST)tCLCL - 17
-2
ns
CST =0
1  CST  7
CST =0
1  CST  7
CST = 0
1  CST  7
ns
tCLCL - 5
2tCLCL - 5
6tCLCL - 5
2tCLCL - 3
3tCLCL - 3
11tCLCL - 3
2tCLCL - 3
3tCLCL - 3
11tCLCL - 3
ns
ns
ns
3tCLCL - 19
(4 x CST + 2)tCLCL- 19
(4 x CST + 10)tCLCL 19
3tCLCL + tCLCH - 19
(4 x CST + 2)tCLCL +
tCLCH - 19
(4 x CST + 10)tCLCL +
tCLCH - 19
tCLCL - 5
2tCLCL - 5
10tCLCL - 5
tCLCL + tCLCH - 5
2tCLCL + tCLCH - 5
10tCLCL + tCLCH - 5
0
tCLCL - 4
2CLCL - 7
6tCLCL - 7
tCHCL - 5
tCLCL + tCHCL - 5
5tCLCL + tCHCL -5
STRETCH
VALUES
CST (MD2:0)
CST = 0
1 CST  3
4  CST  7
ns
2tCLCL - 5
(4 x CST) tCLCL - 3
2tCLCL - 5
(4 x CST)tCLCL - 3
tAVDV2
tAVWL1
UNITS
tCHCL - 3
tAVDV1
Port 7 Address to (RD or PSEN) or WR
Low
MAX
ns
CST = 0
1 CST  3
4  CST  7
CST = 0
1 CST  3
4  CST  7
CST = 0
1 CST  3
4  CST  7
CST = 0
1 CST  3
4  CST  7
CST = 0
ns
1 CST  3
4  CST  7
ns
ns
CST = 0
1  CST  3
4  CST  7
CST = 0
1  CST  3
4  CST  7
ns
ns
tCHCL + 13
tCLCL + tCHCL +12
5tCLCL + tCHCL +12
ns
CST = 0
1  CST  3
4  CST  7
CST = 0
1  CST  3
4  CST  7
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: All parameters apply to both commercial and industrial temperature operation unless otherwise noted.
Note 3: CST is the stretch cycle value as determined by the MD2, MD1, and MD0 bits of the CKCON register. tCLCL, tCLCH, tCHCL are time periods
associated with the internal system clock and are related to the external clock. See the System Clock Time Periods table.
Note 4: All signals characterized with load capacitance of 80pF except Port 0, Port 2, ALE, PSEN, RD, and WR with 100pF. The following
signals, when configured for memory interface, are also characterized with 100pF loading: Port 4 (CE0-3, A16–A19), Port 5.4–5.7
(PCE0-3), Port 6.0–6.5 (CE4-7, A20, A2), Port 7 (demultiplexed mode A0–A7).
Note 5: References to the XTAL or CLK signal in timing diagrams is to assist in determining the relative occurrence of events, not for determing
absolute signal timing with respect to the external clock.
14 of 97
DS80C400 Network Microcontroller
15 of 97
DS80C400 Network Microcontroller
l
16 of 97
DS80C400 Network Microcontroller
NONMULTIPLEXED, 2-CYCLE DATA MEMORY PCE0-3 READ OR WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
NONMULTIPLEXED, 2-CYCLE DATA MEMORY CE0-7 READ
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
PORT 7
17 of 97
A16 -A21
A16 -A21
DS80C400 Network Microcontroller
NONMULTIPLEXED, 2-CYCLE DATA MEMORY CE0-7 WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
PORT 7
NONMULTIPLEXED, 3-CYCLE DATA MEMORY PCE0-3 READ OR WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
PORT 7
18 of 97
A16 -A21
A16 -A21
DS80C400 Network Microcontroller
NONMULTIPLEXED, 3-CYCLE DATA MEMORY CE0-7 READ
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
PORT 7
NONMULTIPLEXED, 3-CYCLE DATA MEMORY CE0-7 WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
PORT 7
19 of 97
A16 -A21
DS80C400 Network Microcontroller
NONMULTIPLEXED, 9-CYCLE DATA MEMORY PCE0-3 READ OR WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
PORT 7
NONMULTIPLEXED, 9-CYCLE DATA MEMORY CE0-7 READ
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
PORT 7
20 of 97
A16 -A21
DS80C400 Network Microcontroller
NONMULTIPLEXED, 9-CYCLE DATA MEMORY CE0-7 WRITE
PORT 4 – CE0  3
PORT 6 – CE4  7
PORT 4/6 ADDRESS
A16 -A21
A16 -A21
A16 -A21
A16 -A21
PORT 7
OW PIN TIMING CHARACTERISTICS (Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V ±10%, TA = -40°C to +85°C.)
PARAMETER
Transmit Reset Pulse Low Time
(Note 2)
Transmit Reset Pulse High Time
(Note 2)
Wait Time for Transmit of Presence
Pulse (Notes 2, 3)
Wait Time for Absence of Presence
Pulse (Notes 2, 4)
Presence Pulse Width (Note 2)
Presence Pulse Sampling Time
(Note 2)
Read/Write Data Time Slot
Low Time for Write 1
Low Time for Write 0
Write Data Sampling Time
Read Data Sampling Time
SYMBOL
STANDARD
MIN
MAX
OVERDRIVE
MIN
MAX
LONGLINE
MIN
MAX
UNITS
tRSTL
500.8
626
50.4
63
500.8
626
s
tRSTH
508.8
636
59.2
74
508.8
636
s
tPDH
15
60
2
6
15
60
s
tPDHCNT
60
75
6.4
8
60
75
s
tPDL
60
240
8
24
60
240
s
tPDS
24
31
2.4
4
30.4
38
s
tSLOT
tLOW1
tLOW0
tWDV
tRDV
68.8
4.8
62.4
15
12
86
6
78
60
15
12
0.8
8
2
1.6
15
1
10
6
2
68.8
7.2
62.4
25
20
86
9
78
60
25
s
s
s
s
s
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: In PMM mode, the master pulls the line low after the first 15s for the remainder of the standard speed 1-Wire routine.
Note 3: This parameter quantifies the wait time for the slave devices to respond to the reset pulse and is dependent on the slave device timing.
Note 4: This parameter quantifies the wait time for the case when no presence pulse detected.
Note 5: The maximum timing figures shown apply only when an exact 1-Wire clock frequency can be achieved from the microcontroller input
clock.
21 of 97
DS80C400 Network Microcontroller
OW PIN TIMING
22 of 97
DS80C400 Network Microcontroller
OWSTP PIN TIMING CHARACTERISTICS (Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V ±10%, TA = -40°C to +85°C.)
PARAMETER
Active Time for Presence Detect
Active Time for Presence Detect Recovery
Active Time for Write 1 Recovery (Notes 2, 3)
Active Time for Write 0 Recovery (Notes 2, 3)
Delay Time for Presence Detect
Delay Time for Presence Detect Recovery (Note 4)
Delay Time for Write 1/Write 0 Recovery
Turn-Off Time for 1-Wire Reset
Turn-Off Time for Write 1/Write 0 (Note 5)
SYMBOL
tON1
tON2
tON3
tON4
tDLY1
tDLY2
tDLY3
tOFF1
tOFF2
STANDARD
MIN
MAX
6.4
8
8
10
51.2
64
6.4
8
0.8
1
399.2
499
0.8
1
1.6
2
0.8
1
OVERDRIVE
MIN
MAX
0.8
1
8
10
7.2
9
0.8
1
0.8
1
31.2
39
0.8
1
1.6
2
0.8
1
UNITS
s
s
s
s
s
s
s
s
s
Note 1: Specifications to -40C are guaranteed by design and not production tested.
Note 2: There is no OWSTP timing difference for sending out and receiving bits within a byte. The difference comes when the last bit of the byte
has been completely sent. At this point, the signal is either enabled continuously until the next reset or time slot begins, or enabled only
for active time write 1 or write 0.
Note 3: When performing a read versus a write time slot, the master provides the same active time for write 1 and write 0. However, the
Schmitt-triggered input from the OW line is sensed every 1s for a high value. If OW is high, the OWSTP signal is enabled. If the OW
line is low, the OWSTP signal remains disabled until a high state is sensed. In all write time slots, a high is sensed immediately.
Note 4: This parameter is the time delay until the master begins to monitor the OW pin level. If the line is already high, then OWSTP is enabled.
If not, it waits to enable OWSTP until the next state machine clock (1s or 50ns) after the OW line recovers.
Note 5: The very first bit in a byte has an extended turn-off time of 4s because of the order of states that the 1-Wire master state machine
must go through.
OWSTP PIN TIMING
23 of 97
DS80C400 Network Microcontroller
ETHERNET MII INTERFACE TIMING CHARACTERISTICS (Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V ±10%, TA = -40°C to +85°C.)
PARAMETER
TXClk Duty Cycle
TXD, TX_EN Data Setup to TXClk
TXD, TX_EN Data Hold from TXClk
RXClk Pulse Width
RXClk to RXD, RX_DV, RX_ER Valid
MDC Period
MDC to Input Data Valid
MDIO Output Data Setup to MDC
MDIO Output Data Hold from MDC
SYMBOL
tTDC
tTSU
tTHD
tRDC
tRDV
tMCLCL
tMDV
tMOS
tMOH
100Mbps
MIN
MAX
14
26
10
2
14
26
10
30
400
300
10
10
Note 1: Specifications to -40C are guaranteed by design and not production tested.
MII INTERFACE TIMING
24 of 97
MIN
140
25
2
140
190
400
10Mbps
MAX
260
260
210
300
10
10
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
DS80C400 Network Microcontroller
SERIAL PORT MODE 0 TIMING CHARACTERISTICS (Note 1)
(VCC3 = 3.0V to 3.6V, VCC1 = 1.8V ±10%, TA = -40°C to +85°C.)
PARAMETER
SYMBOL
Serial Port Clock Cycle Time
tXLXL
CONDITIONS
MIN
SM2 = 0:12 clocks per cycle
tQVXH
SM2 = 1:4 clocks per cycle
tXHQX
Input Data Hold After Clock
Rising
tXHDX
Clock Rising Edge to Input
Data Valid
tXHDV
UNITS
ns
SM2 = 0:12 clocks per cycle
Output Data Hold from Clock
Rising
MAX
12 tCLCL
SM2 = 1:4 clocks per cycle
Output Data Setup to Clock
Rising
TYP
4 tCLCL
10 tCLCL 10
3 tCLCL 10
ns
SM2 = 0:12 clocks per cycle
2 tCLCL 10
SM2 = 1:4 clocks per cycle
tCLCL 10
SM2 = 0:12 clocks per cycle
0
SM2 = 1:4 clocks per cycle
0
SM2 = 0:12 clocks per cycle
SM2 = 1:4 clocks per cycle
Note 1: Specifications to -40C are guaranteed by design and not production tested.
25 of 97
ns
ns
11 tCLCL 20
3 tCLCL 20
ns
DS80C400 Network Microcontroller
SERIAL PORT 0 (SYNCHRONOUS MODE)
HIGH-SPEED OPERATION, TXD CLK = SYSCLK/4 (SM2 = 1)
TRADITIONAL 8051 OPERATION, TXD CLOCK = XTAL/12 (SM2 = 0)
26 of 97
DS80C400 Network Microcontroller
POWER-CYCLE TIMING CHARACTERISTICS
PARAMETER
Crystal Startup Time (Note 1)
Power-On Reset Delay (Note 2)
SYMBOL
MIN
tCSU
tPOR
TYP
MAX
UNITS
65,536
ms
tCLCK
1.8
Note 1: Startup time for crystals varies with load capacitance and manufacturer. Time shown is for an 11.0592MHz crystal manufactured by Fox
Electronics.
Note 2: Reset delay is a synchronous counter of crystal oscillations during crystal startup. Counting begins when the level on the XTAL1 input
meets the VIH2 criteria. At 40MHz, this time is approximately 1.64ms.
POWER-CYCLE TIMING
27 of 97
PORT LATCH
PORT 5
28 of 97
CLOCK AND
MEMORY
CONTROL
MUX
EA
PSEN
ALE
PORT 6
P6.0–P6.7
PORT 4
P4.0– 4.7
SERIAL
PORT 2
PORT LATCH
PORT 7
P7.0–P7.7
PORT LATCH
PORT 2
P2.0–P2.7
TIMED
ACCESS
TIMER 2
PORT LATCH
ADDRESS BUS
INTERRUPT
LOGIC
STACK
POINTER
SERIAL
PORT 1
PORT LATCH
INTRUCTION
REGISTER
SFRs/ SRAM
256 x 8
ONE’S COMP.
ADDER
MATH
ACCELERATOR
B
SRAM
9kk x 8
PORT LATCH
WATCHDOG
BOOT
ROM
64k x 8
MII
MANAGEMENT
BUFFER CONTROL UNIT
MII
I/O
MDIO
PORT 1
OSCILLATOR
RESET
CONTROL
RST
RSTOL
OSCILLATORFAIL DETECT
PROGRAM
COUNTER
PSW
ACCUMULATOR
DATA BUS
PORT LATCH
PORT 3
MDC
OW
OWSTP
P1.0–P1.7
XTAL1
XTAL2
VCC POWER
MONITOR
P5.0–P5.7
CAN 0
CONTROLLER
DPTR0
DPTR1
DPTR2
DPTR3
TIMER 1
TIMER 0
SERIAL
PORT 0
MII I/O (15)
1-WIRE
CONTROLLER
VCC1 (1)
VCC3 (4)
VSS (4)
DS80C400
CAN
SRAM
256 x 8
TIMER 3
P3.0–P3.7
DS80C400 Network Microcontroller
BLOCK DIAGRAM
P0.0–P0.7
PORT 0
DS80C400 Network Microcontroller
PIN DESCRIPTION
PIN
NAME
70
VCC1
+1.8V Core Supply Voltage
VCC3
+3.3V I/O Supply Voltage
VSS
Digital Circuit Ground
12, 36, 62,
87
13, 39, 63,
88
68
ALE
67
PSEN
69
EA
40
MUX
97
RST
98
RSTOL
37
38
XTAL2
XTAL1
86
AD0/D0
85
AD1/D1
84
AD2/D2
83
AD3/D3
82
AD4/D4
81
AD5/D5
80
AD6/D6
79
AD7/D7
89
P1.0
90
P1.1
91
P1.2
92
P1.3
93
P1.4
94
P1.5
95
P1.6
96
P1.7
66
A8
65
A9
64
A10
61
A11
60
A12
FUNCTION
Address Latch Enable, Output. When the MUX pin is low, this pin outputs a clock to latch the external address
LSB from the multiplexed address/data bus on Port 0. This signal is commonly connected to the latch enable of
an external transparent latch. ALE has a pulse width of 1.5 XTAL1 cycles and a period of four XTAL1 cycles.
When the MUX pin is high, the pin toggles continuously if the ALEOFF bit is cleared. ALE is forced high when
the device is in a reset condition or if the ALEOFF bit is set while the MUX pin is high.
Program Store Enable, Output. This signal is the chip enable for external program or merged program/data
memory. PSEN provides an active-low pulse and is driven high when external memory is not being accessed.
External Access Enable, Input. Connect to GND to use external program memory. Connect to VCC to use
internal ROM.
Multiplex/Demultiplex Select, Input. This pin selects if the address/data bus operates in multiplexed (MUX =
0) or demultiplexed (MUX = 1) mode. The MUX pin is sampled only on a power-on reset.
Reset, Input. The RST input pin contains a Schmitt voltage input to recognize external active-high reset inputs.
The pin also employs an internal pulldown resistor to allow for a combination of wired-OR external-reset
sources. An RC circuit is not required for power-up, as the device provides this function internally.
Reset Output Low, Output. This active-low signal is asserted when the microcontroller has entered reset
through the RST pin; during crystal warm-up period following power-on or stop mode; during a watchdog timer
reset; during an oscillator failure (if OFDE = 1); whenever VCC1  VRST1 or VCC3  VRST3. When connecting the
DS80C400 to an external PHY, do not connect the RSTOL to the reset of the PHY. Doing so may disable the
Ethernet transmit.
XTAL1, XTAL2. Crystal oscillator pins support fundamental mode, parallel resonant, AT cut crystals. XTAL1 is
the input if an external clock source is used in place of a crystal. XTAL2 is the output of the crystal amplifier.
AD0–7 (Port 0), I/O. When the MUX pin is connected low, Port 0 is the multiplexed address/data bus. While
ALE is high, the LSB of a memory address is presented. While ALE falls, the port transitions to a bidirectional
data bus. When the MUX pin is connected high, Port 0 functions as the bidirectional data bus. Port 0 cannot be
modified by software. The reset condition of Port 0 pins is high. No pullup resistors are needed.
Port
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
Alternate Function
AD0/D0 (Address)/Data 0
AD1/D1 (Address)/Data 1
AD2/D2 (Address)/Data 2
AD3/D3 (Address)/Data 3
AD4/D4 (Address)/Data 4
AD5/D5 (Address)/Data 5
AD6/D6 (Address)/Data 6
AD7/D7 (Address)/Data 7
Port 1, I/O. Port 1 can function as either an 8-bit, bidirectional I/O port or as an alternate interface for internal
resources. The reset condition of Port 1 is all bits at logic 1 through a weak pullup. The logic 1 state also serves
as an input mode, since external circuits writing to the port can override the weak pullup. When software clears
any port pin to 0, a strong pulldown is activated that remains on until either a 1 is written to the port pin or a
reset occurs. Writing a 1 after the port has been at 0 activates a strong transition driver, followed by a weaker
sustaining pullup. Once the momentary strong driver turns off, the port once again becomes the output (and
input) high state.
Port
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Alternate Function
T2 External I/O for Timer/Counter 2
T2EX Timer/Counter 2 Capture/Reload Trigger
RXD1 Serial Port 1 Receive
TXD1 Serial Port 1 Transmit
INT2 External Interrupt 2 (Positive Edge Detect)
INT3 External Interrupt 3 (Negative Edge Detect)
INT4 External Interrupt 4 (Positive Edge Detect)
INT5 External Interrupt 5 (Negative Edge Detect)
A15–A8 (Port 2), Output. Port 2 serves as the MSB for external addressing. The port automatically asserts the
address MSB during external ROM and RAM access. Although the Port 2 SFR exists, the SFR value never
appears on the pins (due to memory access). Therefore, accessing the Port 2 SFR is only useful for MOVX A,
@Ri or MOVX @Ri, A instructions, which use the Port 2 SFR as the external address MSB.
Port
P2.0
P2.1
Alternate Function
A8 Program/Data Memory Address 8
A9 Program/Data Memory Address 9
29 of 97
DS80C400 Network Microcontroller
PIN
NAME
59
A13
58
A14
57
A15
20
P3.0
21
P3.1
22
P3.2
23
P3.3
24
P3.4
25
P3.5
26
P3.6
27
P3.7
48
P4.0
47
P4.1
46
P4.2
45
P4.3
44
P4.4
43
P4.5
42
P4.6
41
P4.7
35
P5.0
34
P5.1
33
P5.2
32
P5.3
31
P5.4
30
P5.5
29
P5.6
28
P5.7
56
P6.0
55
P6.1
54
P6.2
53
P6.3
52
P6.4
FUNCTION
P2.2
A10 Program/Data Memory Address 10
P2.3
A11 Program/Data Memory Address 11
P2.4
A12 Program/Data Memory Address 12
P2.5
A13 Program/Data Memory Address 13
P2.6
A14 Program/Data Memory Address 14
P2.7
A15 Program/Data Memory Address 15
Port 3, I/O. Port 3 functions as an 8-bit, bidirectional I/O port, and as an alternate interface for several resources
found on the traditional 8051. The reset condition of Port 3 is all bits at logic 1 through a weak pullup. The logic
1 state also serves as an input mode, since external circuits writing to the port can override the weak pullup.
When software clears any port pin to 0, the device activates a strong pulldown that remains on until either a 1 is
written to the port pin or a reset occurs. Writing a 1 after the port has been at 0 activates a strong transition
driver, followed by a weaker sustaining pullup. Once the momentary strong driver turns off, the port once again
becomes the output (and input) high state.
Port
Alternate Function
P3.0
RXD0 Serial Port 0 Receive
P3.1
TXD0 Serial Port 0 Transmit
INT0 External Interrupt 0
P3.2
P3.3
INT1 External Interrupt 1
P3.4
T0 Timer 0 External Input
P3.5
T1/CLKO Timer 1 External Input/External Clock Output
WR External Data Memory Write Strobe
P3.6
P3.7
RD External Data Memory Read Strobe
Port 4, I/O. Port 4 is composed of eight pins that are user programmable as I/O, extended program memory
chip enables, or extended address lines. The configuration of the eight pins is established through the
programming of the port 4 control register (P4CNT). Following a reset, and if EA is low, P4.3 to P4.1 are driven
high and are assigned as chip enables. Port pins P4.7 to P4.4 and P4.0 are cleared to low state and are
assigned as addresses and chip enable, respectively. Additional information on external memory interfacing is
found in the port 4 control register SFR description and other sections in the High-Speed Microcontroller User’s
Guide: Network Microcontroller Supplement.
Port
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
Alternate Function
CE0 Program Memory Chip Enable 0
CE1 Program Memory Chip Enable 1
CE2 Program Memory Chip Enable 2
CE3 Program Memory Chip Enable 3
A16 Program/Data Memory Address 16
A17 Program/Data Memory Address 17
A18 Program/Data Memory Address 18
A19 Program/Data Memory Address 19
Port 5, I/O. Port 5 can function as an 8-bit, bidirectional I/O port, the CAN interface, Timer 3 input, and/or as
peripheral-enable signals. The reset condition of Port 5 is all bits at logic 1 through a weak pullup. The logic 1
state also serves as an input mode, since external circuits writing to the port can override the weak pullup.
When software clears any port pin to 0, the device activates a strong pulldown that remains on until either a 1 is
written to the port pin or a reset occurs. Writing a 1 after the port has been at 0 activates a strong transition
driver, followed by a weaker sustaining pullup. Once the momentary strong driver turns off, the port once again
becomes the output (and input) high state.
Port
Alternate Function
P5.0
C0TX CAN0 Transmit Output
P5.1
C0RX CAN0 Receive Input
P5.2
T3 Timer 3 External Input
P5.3
None
PCE0 Peripheral Chip Enable 0
P5.4
P5.5
PCE1 Peripheral Chip Enable 1
P5.6
PCE2 Peripheral Chip Enable 2
P5.7
PCE3 Peripheral Chip Enable 3
Port 6, I/O. Port 6 can function as an 8-bit, bidirectional I/O port, as program and data memory address/chipenable signals, and/or a third serial port. The reset condition of Port 6 is all bits at logic 1 through a weak pullup.
The logic 1 state also serves as an input mode, since external circuits writing to the port can override the weak
pullup. When software clears any port pin to 0, the device activates a strong pulldown that remains on until
either a 1 is written to the port pin or a reset occurs. Writing a 1 after the port has been at 0 activates a strong
transition driver, followed by a weaker sustaining pullup. Once the momentary strong driver turns off, the port
once again becomes the output (and input) high state.
Port
P6.0
Alternate Function
CE4 Program Memory Chip Enable 4
30 of 97
DS80C400 Network Microcontroller
PIN
NAME
51
P6.5
50
P6.6
49
P6.7
78
A0
77
A1
76
A2
75
A3
74
A4
73
A5
72
A6
71
A7
8
TXClk
7
TX_EN
3
4
5
6
TXD.3
TXD.2
TXD.1
TXD.0
10
RXClk
11
RX_DV
9
RX_ER
17
16
15
14
RXD.3
RXD.2
RXD.1
RXD.0
1
CRS
2
COL
18
MDC
FUNCTION
P6.1
CE5 Program Memory Chip Enable 5
P6.2
CE6 Program Memory Chip Enable 6
P6.3
CE7 Program Memory Chip Enable 7
P6.4
A20 Program/Data Memory Address 20
P6.5
A21 Program/Data Memory Address 21
P6.6
RXD2 Serial Port 2 Receive
P6.7
TXD2 Serial Port 2 Transmit
Port 7, I/O. Port 7 can function as either an 8-bit, bidirectional I/O port or the nonmultiplexed A0–A7 signals
(when the MUX pin = 1). The reset condition of Port 7 is all bits at logic 1 through a weak pullup. The logic 1
state also serves as an input mode, since external circuits writing to the port can override the weak pullup.
When software clears any port pin to 0, a strong pulldown is activated that remains on until either a 1 is written
to the port pin or a reset occurs. Writing a 1 after the port has been at 0 activates a strong transition driver,
followed by a weaker sustaining pullup. Once the momentary strong driver turns off, the port once again
becomes the output (and input) high state.
Port
Alternate Function
P7.0
A0 Program/Data Memory Address 0
P7.1
A1 Program/Data Memory Address 1
P7.2
A2 Program/Data Memory Address 2
P7.3
A3 Program/Data Memory Address 3
P7.4
A4 Program/Data Memory Address 4
P7.5
A5 Program/Data Memory Address 5
P7.6
A6 Program/Data Memory Address 6
P7.7
A7 Program/Data Memory Address 7
Transmit Clock, Input. The transmit clock is a continuous clock sourced from the Ethernet PHY controller. It is
used to provide timing reference for transferring of TX_EN and TXD[3:0] signals from the MAC to the external
Ethernet PHY controller. The input clock frequency of TXClk should be 25MHz for 100Mbps operation and
2.5MHz for 10Mbps operation. For ENDEC operation, TXClk serves the same function, but the input clock
frequency should be 10MHz.
Transmit Enable, Output. The transmit enable is an active-high output and is synchronous with respect to the
TXClk signal. TX_EN is used to indicate valid nibbles of data for transmission on the MII pins TXD.3–TXD.0.
TX_EN is asserted with the first nibble of the preamble and remains asserted while all nibbles to be transmitted
are presented on the TXD.3–TXD.0 pins. TX_EN negates prior to the first TXClk following the final nibble of the
frame. TX_EN serves the same function for ENDEC operation.
Transmit Data, Output. The transmit data outputs provide 4-bit nibbles of data for transmission over the MII.
The transmit data is synchronous with respect to the TXClk signal. For each TXClk period when TX_EN is
asserted, TXD.3–TXD.0 provides the data for transmission to the Ethernet PHY controller. When TX_EN is
deasserted, the TXD data should be ignored. For ENDEC operation, only TXD.0 is used for transmission of
frames.
Receive Clock, Input. The receive clock is a continuous clock sourced from the Ethernet PHY controller. It is
used to provide timing reference for transferring of RX_DV, RX_ER, and RXD[3:0] signals from the external
Ethernet PHY controller to the MAC. The input clock frequency of RXClk should be 25MHz for 100Mbps
operation and 2.5MHz for 10Mbps operation. For ENDEC operation, RXClk serves the same function, but the
input clock frequency should be 10MHz.
Receive Data Valid, Input. The receive data valid is an active-high input from the external Ethernet PHY
controller and is synchronous with respect to the RXClk signal. RX_DV is used to indicate valid nibbles of data
for reception on the MII pins RXD.3–RXD.0. RX_DV is asserted continuously from the first nibble of the frame
through the final nibble. RX_DV negates prior to the first RXClk following the final nibble. RX_DV serves the
same function for ENDEC operation.
Receive Error, Input. The receive error is an active-high input from the external Ethernet PHY controller and is
synchronous with respect to the RXClk signal. RX_ER is used to indicate to the MAC that an error (e.g., a
coding error, or any error detectable by the PHY) was detected somewhere in the frame presently being
transmitted by the PHY. RX_ER has no effect on the MAC while RX_DV is deasserted. RX_ER should be low
for ENDEC operation.
Receive Data, Input. The receive data inputs provide 4-bit nibbles of data for reception over the MII. The
receive data is synchronous with respect to the RXClk signal. For each RXClk period when RX_DV is asserted,
RXD.3–RXD.0 have the data to be received by the MAC. When RX_DV is deasserted, the RXD data should be
ignored. For ENDEC operation, only RXD.0 is used for reception of frames.
Carrier Sense, Input. The carrier sense signal is an active-high input and should be asserted by the external
Ethernet PHY controller when either the transmit or receive medium is not idle. CRS should be deasserted by
the PHY when the transmit and receive mediums are idle. The PHY should ensure that the CRS signal remains
asserted throughout the duration of a collision condition. The transitions on the CRS signal need not be
synchronous to TXClk or RXClk. CRS serves the same function for ENDEC operation.
Collision Detect, Input. The collision detect signal is an active-high input and should be asserted by the
external Ethernet PHY controller upon detection of a collision on the medium. The PHY should ensure that COL
remains asserted while the collision condition persists. The transitions on the COL signal need not be
synchronous to TXClk or RXClk. The COL signal is ignored by the MAC when operating in full-duplex mode.
COL serves the same function for ENDEC operation.
MII Management Clock, Output. The MII management clock is generated by the MAC for use by the external
Ethernet PHY controller as a timing referenced for transferring information on the MDIO pin. MDC is a periodic
31 of 97
DS80C400 Network Microcontroller
PIN
NAME
19
MDIO
99
OW
100
OWSTP
FUNCTION
signal that has no maximum high or low times. The minimum high and low times are 160ns each. The minimum
period for MDC is 400ns independent of the period of TXClk and RXClk.
MII Management Input/Output. The MII management I/O is the data pin for serial communication with the
external Ethernet PHY controller. In a read cycle, data is driven by the PHY to the MAC synchronously with
respect to the MDC clock. In a write cycle, data from the MAC is output to the external PHY synchronously with
respect to the MDC clock.
1-Wire Data, I/O. The 1-Wire data pin is an open-drain, bidirectional data bus for the 1-Wire Bus Master.
External 1-Wire slave devices are connected to this pin. This pin must be pulled high by an external resistor,
normally 2.2k.
Strong Pullup Enable, Output. This 1-Wire pin is an open-drain active-low output used to enable an external
strong pullup for the 1-Wire bus. This pin must be pulled high by an external resistor, normally 10k. This
functionality helps recovery times when the 1-Wire bus is operated in overdrive and long-line standard
communication modes. It can optionally be enabled while the bus master is in the idle state for slave devices
requiring sustained high-current operation.
FEATURES (continued)

Advanced Power Management
Energy Saving 1.8V Core
3.3V I/O Operation, 5V Tolerant
Power-Management, Idle, and Stop Mode
Operations with Switchback Feature
Ethernet and CAN Shutdown Control for Power
Conservation
Early Warning Power-Fail Interrupt
Power-Fail Reset

Enhanced Memory Architecture
Selectable 8/10-Bit Stack Pointer for High-Level
Language Support
1kB Additional On-Chip SRAM Usable as
Stack/Data Memory
16-Bit/24-Bit Paged/24-Bit Contiguous Modes
Selectable Multiplexed/Nonmultiplexed External
Memory Interface
Merged Program/Data Memory Space Allows InSystem Programming
Defaults to True 8051-Memory Compatibility
DETAILED DESCRIPTION
The DS80C400 network microcontroller offers the highest integration available in an 8051 device. Peripherals
include a 10/100 Ethernet MAC, three serial ports, a CAN 2.0B controller, 1-Wire Master, and 64 I/O pins. To
enable access to the network, a full application-accessible TCP IPv4/6 network stack and OS are provided in ROM.
The network stack supports up to 32 simultaneous TCP connections and can transfer up to 5Mbps through the
Ethernet MAC. Its maximum system-clock frequency of 75MHz results in a minimum instruction cycle time of 54ns.
Access to large program or data memory areas is simplified with a 24-bit addressing scheme that supports up to
16MB of contiguous memory. To accelerate data transfers between the microcontroller and memory, the
DS80C400 provides four data pointers, each of which can be configured to automatically increment or decrement
upon execution of certain data pointer-related instructions. The DS80C400’s hardware math accelerator further
increases the speed of 32-bit and 16-bit multiply and divide operations as well as high-speed shift, normalization,
and accumulate functions.
With extensive networking and I/O capabilities, the DS80C400 is equipped to serve as a central controller in a
multitiered network. The 10/100 Ethernet media access controller (MAC) enables the DS80C400 to access and
communicate over the Internet. While maintaining a presence on the Internet, the microcontroller can actively
control lower tier networks with dedicated on-chip hardware. These hardware resources include a full CAN 2.0B
controller, a 1-Wire net controller, three full-duplex serial ports, and eight 8-bit ports (up to 64 digital I/O pins).
Instant connectivity and networking support are provided through an embedded 64kB ROM. This ROM contains
firmware to perform a network boot over an Ethernet connection using DHCP in conjunction with TFTP. The ROM
firmware realizes a full, application-accessible TCP/IP stack, supporting both IPv4 and IPv6, and implements UDP,
TCP, DHCP, ICMP, and IGMP. In addition, a priority-based, preemptive task scheduler is also included. The
firmware has been structured so that a MAC address can optionally be acquired from an IEEE-registered DS2502E48.
The 10/100 Ethernet MAC featured on the DS80C400 complies with both the IEEE 802.3 MII and ENDEC PHY
interface standards. The MII interface supports 10/100Mbps bus operation, while the ENDEC interface supports
10Mbps operation. The MAC has been designed for low-power standard operation and can optionally be placed
into an ultra-low-power sleep mode, to be awakened manually or by detection of a Magic Packet or wake-up frame.
Incorporating a buffer control unit reduces the burden of Ethernet traffic on the CPU. This unit, after initial
32 of 97
DS80C400 Network Microcontroller
configuration through an SFR interface, manages all Tx/Rx packet activity and status reporting through an on-chip
8kB SRAM. To further reduce host (DS80C400) software intervention, the MAC can be set up to generate a
hardware interrupt following each transmit or receive status report. The DS80C400 MAC can be operated in halfduplex or full-duplex mode with flow control, and provides multicast/broadcast-address filtering modes as well as
VLAN tag-recognition capability.
The DS80C400 features a full-function CAN 2.0B controller. This controller provides 15 total message centers, 14
of which can be configured as either transmit or receive buffers and one that can serve as a receive double buffer.
The device supports standard 11-bit or 29-extended message identifiers, and offers two separate 8-bit media
masks and media arbitration fields to support the use of higher-level CAN protocols such as DeviceNet and SDS. A
special auto-baud mode allows the CAN controller to quickly determine required bus timing when inserted into a
new network. A SIESTA sleep mode has been made available for times when the CAN controller can be placed
into a power-saving mode.
The DS80C400 has resources that far exceed those normally provided on a standard 8-bit microcontroller. Many
functions, which might exist as peripheral circuits to a microcontroller, have been integrated into the DS80C400.
Some of the integrated functions of the DS80C400 include 16 interrupt sources (six external), four timer/counters, a
programmable watchdog timer, a programmable IrDA output clock, an oscillator-fail detection circuit, and an
internal 2X/4X clock multiplier. This frequency multiplier allows the microcontroller to operate at full speed with a
reduced crystal frequency, reducing EMI.
Advanced power-management support positions the DS80C400 for portable and power-conscious applications.
The low-voltage microcontroller core runs from a 1.8V supply while the I/O remains 5V tolerant, operating from a
3.3V supply. A power-management mode (PMM) allows software to switch from the standard machine cycle rate of
4 clocks per cycle to 1024 clocks per cycle. For example, 40MHz standard operation has a machine cycle rate of
10MHz. In PMM, at the same external clock speed, software can select a 39kHz machine cycle rate, considerably
reducing power consumption. The microcontroller can be configured to automatically switch back from PMM to the
faster mode in response to external interrupts or serial port activity. The DS80C400 provides the ability to place the
CPU into an idle state or an ultra-low-power stop-mode state. As protection against brownout and power-fail
conditions, the microcontroller is capable of issuing an early warning power-fail interrupt and can generate a powerfail reset.
Defaulting to true 8051-memory compatibility (when the ROM is disabled), the microcontroller is most powerful
when taking advantage of its enhanced memory architecture. The DS80C400 has a selectable 10-bit stack pointer
that can address up to 1kB of on-chip SRAM stack space for increased code efficiency. It can be operated in a 24bit paged or 24-bit contiguous address mode, giving access to a much larger address range than the standard 16bit address mode. Support for merged program and data memory access allows in-system programming, and it can
be configured to internally demultiplex data and the lowest address byte, thereby eliminating the need for an
external latch and potentially allowing the use of slower memory devices.
80C32 COMPATIBILITY
The DS80C400 is a CMOS 80C32-compatible microcontroller designed for high performance. Every effort has
been made to keep the core device familiar to 80C32 users while adding many enhanced features. The DS80C400
provides the same timer/counter resources, full duplex serial port, 256 Bytes of scratchpad RAM, and I/O ports as
the standard 80C32. Timers default to 12 oscillator clocks per tick operation to keep timing compatible with original
8051 systems. New hardware functions are accessed using special function registers (SFRs) that do not overlap
with standard 80C32 locations. All instructions perform exactly the same functions as their 8051 counterparts. Their
effect on bits, flags, and other status functions is identical. Because the device runs the standard 8051 instruction
set, in general, software written for existing 80C32-based systems work on the DS80C400. The primary exceptions
are related to timing-critical issues, since the high-performance core of the microcontroller executes instructions
much faster than the original, both in absolute and relative number of clocks.
The relative time of two DS80C400 instructions might differ from the traditional 8051. For example, in the original
architecture the “MOVX A, @DPTR” instruction and the “MOV direct, direct” instruction required the same amount
of time: two machine cycles or 24 oscillator cycles. In its default configuration (machine cycle = 4 oscillator cycles),
the DS80C400 executes the “MOVX A, @DPTR” instruction in as little as two machine cycles or 8 oscillator cycles,
but the “MOV direct, direct” uses three machine cycles or 12 oscillator cycles. While both are faster than their
original counterparts, they now have different execution times. Examine the timing of each instruction for familiarity
33 of 97
DS80C400 Network Microcontroller
with the changes. Note that a machine cycle now requires just 4 clocks, and provides one ALE pulse per cycle.
Most instructions require only one or two cycles, but some require as many as four or five. Refer to the High-Speed
Microcontroller User’s Guide and High-Speed Microcontroller User’s Guide: Network Microcontroller Supplement
for individual instruction-timing details and for calculating the absolute timing of software loops. Also remember that
the counter/timers default to run at the traditional 12 clocks per increment. This means that timer-based events still
occur at the standard intervals, but that code now executes at a higher speed relative to the timers. Timers
optionally can be configured to run at the faster 4 clocks per increment to take advantage of faster controller
operation.
Memory interfacing can be performed identically to the standard 80C32. The high-speed nature of the DS80C400
core slightly changes the interface timing, and designers are advised to consult the timing diagrams in this data
sheet for more information.
This data sheet provides only a summary and overview of the DS80C400. Detailed descriptions are available in the
corresponding user’s guide. This data sheet assumes a familiarity with the architecture of the standard 80C32. In
addition to the basic features of that device, the DS80C400 incorporates many new features.
PERFORMANCE OVERVIEW
The DS80C400’s higher performance comes not just from increasing the clock frequency but from a more efficient
design. This updated core removes the dummy memory cycles that are present in a standard, 12 clock-permachine cycle 8051. In the DS80C400, a machine cycle requires only 4 clocks. Thus the fastest instruction, 1
machine cycle in duration, executes three times faster for the same crystal frequency. The majority of instructions
on the DS80C400 experience a 3-to-1 speed improvement, while a few execute between 1.5 and 2.4 times faster.
One instruction, INC DPTR, actually executes in fewer machine cycles (1 machine cycle vs. 2 machine cycles
originally required), thus it sees a 6X throughput improvement over the original 8051. Regardless of specific
performance improvements, all instructions are faster than the original 8051.
Improvement of individual programs depend on the actual mix of instructions used. Speed-sensitive applications
should make the most use of instructions that are at least three times faster. However, given the large number of 3to-1 improved op codes, dramatic speed improvements are likely for any arbitrary combination of instructions. The
core architectural improvements and the submicron-CMOS design result in a peak instruction cycle of 54ns (18.75
million instructions per second, i.e., MIPS). To further increase performance, auto-increment/decrement and autotoggle enhancements have been implemented for the quad data pointer to allow the user to eliminate wasted
instructions when moving blocks of memory.
SPECIAL FUNCTION REGISTERS (SFRS)
SFRs control most special features of the microcontroller. They allow the device to have many new features but
use the standard 8051 instruction set. When writing software to use a new feature, an equate statement defines the
SFR to the assembler or compiler. This is the only change needed to access the new function. The DS80C400
duplicates the SFRs contained in the standard 80C32. Table 1 shows the register addresses and bit locations. The
High-Speed Microcontroller User’s Guide: Network Microcontroller Supplement contains a full description of all
SFRs.
34 of 97
DS80C400 Network Microcontroller
Table 1. SFR Addresses and Bit Locations
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
ADDRESS
P4
P4.7/A19
P4.6/A18
P4.5/A17
P4.4/A16
P4.3/CE3
P4.2/CE2
P4.1/CE1
P4.0/CE0
80h
SP
81h
DPL
82h
DPH
83h
DPL1
84h
DPH1
85h
DPS
ID1
ID0
TSL
AID
SEL1
—
—
SEL0
PCON
SMOD_0
SMOD0
OFDF
OFDE
GF1
GF0
STOP
IDLE
87h
TCON
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
88h
TMOD
GATE
C/T
M1
M0
GATE
C/T
M1
M0
TL0
86h
89h
8Ah
TL1
8Bh
TH0
8Ch
TH1
8Dh
CKCON
WD1
WD0
T2M
T1M
T0M
MD2
MD1
MD0
P1
P1.7/INT5
P1.6/INT4
P1.5/INT3
P1.4/INT2
P1.3/TXD
P1.2/RXD1
P1.1/T2EX
P1.0/T2
90h
EXIF
IE5
IE4
IE3
IE2
CKRY
RGMD
RGSL
BGS
91h
P4CNT
—
—
P4CNT.5
P4CNT.4
P4CNT.3
P4CNT.2
P4CNT.1
P4CNT.0
DPX
8Eh
92h
93h
DPX1
95h
C0RMS0
96h
C0RMS1
SCON0
97h
SM0/FE_0
SM1_0
SM2_0
REN_0
TB8_0
RB8_0
TI_0
RI_0
98h
—
—
—
—
—
—
ESP.1
ESP.0
9Bh
—
—
MROM
BPME
BROM
SA
AM1
AM0
9Dh
SBUF0
ESP
99h
AP
ACON
9Ch
C0TMA0
9Eh
C0TMA1
9Fh
P2
P2.7/A15
P2.6/A14
P2.5/A13
P2.4/A12
P2.3/A11
P2.2/A10
P2.1/A9
P2.0/A8
A0h
A1h
P5
P5.7/PCE3
P5.6/PCE2
P5.5/PCE1
P5.4/PCE0
P5.3
P5.2/T3
P5.1/C0RX
P5.0/C0TX
P5CNT
—
CAN0BA
—
—
C0_I/O
P5CNT.2
P5CNT.1
P5CNT.0
A2h
C0C
ERIE
STIE
PDE
SIESTA
CRST
AUTOB
ERCS
SWINT
A3h
C0S
BSS
EC96/128
WKS
RXS
TXS
ER2
ER1
ER0
A4h
C0IR
INTIN7
INTIN6
INTIN5
INTIN4
INTIN3
INTIN2
INTIN1
INTIN0
C0TE
C0RE
IE
A5h
A6h
A7h
EA
ES1
ET2
ES0
ET1
EX1
ET0
EX0
A8h
SADDR0
A9h
SADDR1
AAh
C0M1C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
ABh
C0M2C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
ACh
C0M3C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
ADh
C0M4C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
AEh
C0M5C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
AFh
P3
P3.7/RD
P3.6/WR
P3.5/T1
P3.4/T0
P3.3/INT1
P3.2/INT0
P3.1/TXD0
P3.0/RXD0
B0h
P6
P6.7/TXD2
P6.6/RXD2
P6.5/A21
P6.4/A20
P6.3/CE7
P6.2/CE6
P6.1/CE5
P6.0/CE4
B1h
P6CNT
—
—
P6CNT.5
P6CNT.4
P6CNT.3
P6CNT.2
P6CNT.1
P6CNT.0
B2h
C0M6C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
B3h
C0M7C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
B4h
C0M8C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
B5h
35 of 97
DS80C400 Network Microcontroller
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
C0M9C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
B6h
C0M10C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
B7h
IP
—
PS1
PT2
PS0
PT1
PX1
PT0
PX0
B8h
SADEN0
ADDRESS
B9h
SADEN1
BAh
C0M11C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
BBh
C0M12C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
BCh
C0M13C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
BDh
C0M14C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
BEh
C0M15C
MSRDY
ETI
ERI
INTRQ
EXTRQ
MTRQ
ROW/TIH
DTUP
BFh
SCON1
SM0/FE_1
SM1_1
SM2_1
REN_1
TB8_1
RB8_1
TI_1
RI_1
C0h
SBUF1
C1h
PMR
CD1
CD0
SWB
CTM
4X/2X
ALEOFF
—
—
STATUS
PIP
HIP
LIP
—
SPTA1
SPRA1
SPTA0
SPRA0
C5h
MCON
IDM1
IDM0
CMA
—
PDCE3
PDCE2
PDCE1
PDCE0
C6h
T2CON
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
C8h
T2MOD
—
—
—
D13T1
D13T2
—
T2OE
DCEN
TA
C4h
C7h
RCAP2L
C9h
CAh
RCAP2H
CBh
TL2
CCh
TH2
CDh
COR
IRDACK
—
—
C0BPR7
C0BPR6
COD1
COD0
CLKOE
PSW
CY
AC
F0
RS1
RS0
OV
F1
P
D0h
MCNT0
LSHIFT
CSE
SCE
MAS4
MAS3
MAS2
MAS1
MAS0
D1h
MCNT1
MST
MOF
SCB
CLM
—
—
—
—
D2h
MA
CEh
D3h
MB
D4h
MC
D5h
MCON1
—
—
—
—
PDCE7
PDCE6
PDCE5
PDCE4
D6h
MCON2
WPIF
WPR2
WPR1
WPR0
WPE3
WPE2
WPE1
WPE0
D7h
WDCON
SMOD_1
POR
EPFI
PFI
WDIF
WTRF
EWT
RWT
D8h
SADDR2
D9h
BPA1
DAh
BPA2
DBh
BPA3
DCh
ACC
E0h
OCAD
E1h
CSRD
E3h
CSRA
E4h
EBS
FPE
RBF
—
BS4
BS3
BS2
BS1
BS0
E5h
BCUC
BUSY
EPMF
TIF
RIF
BC3
BC2
BC1
BC0
E7h
EIE
EPMIE
C0IE
EAIE
EWDI
EWPI
ES2
ET3
EX2-5
BCUD
E6h
MXAX
E8h
EAh
DPX2
EBh
DPX3
EDh
OWMAD
—
—
—
—
—
OWMDR
A2
A1
A0
EEh
EFh
B
F0h
SADEN2
F1h
DPL2
F2h
36 of 97
DS80C400 Network Microcontroller
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
DPH2
ADDRESS
F3h
DPL3
F4h
DPH3
F5h
DPS1
ID3
ID2
—
—
—
—
—
—
F6h
F7h
STATUS1
—
—
—
—
V1PF
V3PF
SPTA2
SPRA2
EIP
EPMIP
C0IP
EAIP
PWDI
PWPI
PS2
PT3
PX2-5
F8h
P7
P7.7/A7
P7.6/A6
P7.5/A5
P7.4/A4
P7.3/A3
P7.2/A2
P7.1/A1
P7.0/A0
F9h
TL3
FBh
TH3
FCh
T3CM
TF3
TR3
T3M
SMOD_2
GATE
C/T3
M1
M0
FDh
SCON2
SM0/FE_2
SM1_2
SM2_2
REN_2
TB8_2
RB8_2
TI_2
RI_2
FEh
SBUF2
FFh
Note: Shaded bits are timed-access protected.
37 of 97
DS80C400 Network Microcontroller
Table 2. SFR Reset Values
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
ADDRESS
P4
SP
DPL
DPH
DPL1
DPH1
DPS
PCON
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON
P1
EXIF
P4CNT
DPX
DPX1
C0RMS0
C0RMS1
SCON0
SBUF0
ESP
AP
ACON
C0TMA0
C0TMA1
P2
P5
P5CNT
C0C
C0S
C0IR
C0TE
C0RE
IE
SADDR0
SADDR1
C0M1C
C0M2C
C0M3C
C0M4C
C0M5C
P3
P6
P6CNT
C0M6C
C0M7C
C0M8C
C0M9C
C0M10C
IP
SADEN0
SADEN1
C0M11C
C0M12C
C0M13C
C0M14C
C0M15C
SCON1
SBUF1
PMR
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
1
0
1
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
Special
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
1
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
1
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
Special
1
0
0
0
0
0
0
1
0
Special
0
0
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
Special
1
0
0
0
0
0
0
1
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
Special
1
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
80h
81h
82h
83h
84h
85h
86h
87h
88h
89h
8Ah
8Bh
8Ch
8Dh
8Eh
90h
91h
92h
93h
95h
96h
97h
98h
99h
9Bh
9Ch
9Dh
9Eh
9Fh
A0h
A1h
A2h
A3h
A4h
A5h
A6h
A7h
A8h
A9h
AAh
ABh
ACh
ADh
AEh
AFh
B0h
B1h
B2h
B3h
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
BCh
BDh
BEh
BFh
C0h
C1h
C4h
38 of 97
DS80C400 Network Microcontroller
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
ADDRESS
STATUS
MCON
TA
T2CON
T2MOD
RCAP2L
RCAP2H
TL2
TH2
COR
PSW
MCNT0
MCNT1
MA
MB
MC
MCON1
MCON2
WDCON
SADDR2
BPA1
BPA2
BPA3
ACC
OCAD
CSRD
CSRA
EBS
BCUD
BCUC
EIE
MXAX
DPX2
DPX3
OWMAD
OWMDR
B
SADEN2
DPL2
DPH2
DPL3
DPH3
DPS1
STATUS1
EIP
P7
TL3
TH3
T3CM
SCON2
SBUF2
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
1
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
1
0
1
0
0
0
0
0
0
0
1
0
1
0
0
0
0
1
0
0
0
0
0
0
1
0
Special
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
0
0
0
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
Special
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
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
0
0
0
1
1
0
1
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
Special
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
1
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
1
0
0
0
0
0
C5h
C6h
C7h
C8h
C9h
CAh
CBh
CCh
CDh
CEh
D0h
D1h
D2h
D3h
D4h
D5h
D6h
D7h
D8h
D9h
DAh
DBh
DCh
E0h
E1h
E3h
E4h
E5h
E6h
E7h
E8h
EAh
EBh
EDh
EEh
EFh
F0h
F1h
F2h
F3h
F4h
F5h
F6h
F7h
F8h
F9h
FBh
FCh
FDh
FEh
FFh
Note: Shaded bits are timed-access protected. “Special” bits are affected only by certain types of reset. Refer to the user’s guide for details.
39 of 97
DS80C400 Network Microcontroller
TIMED-ACCESS PROTECTION
Selected SFR bits are critical to operation, making it desirable to protect them against an accidental write
operation. The timed-access procedure prevents errant behavior from accidentally altering bits that would seriously
affect microcontroller operation. The timed-access procedure requires that the write of a protected bit be
immediately preceded by the following two instructions:
MOV
MOV
0C7h, #0AAh
0C7h, #55h
Writing an AAh followed by a 55h to the timed access register (location C7h), opens a three-cycle window that
allows software to modify one of the protected bits. The protected bits are:
SFR
BIT(S)
NAME
EXIF (91h)
EXIF.0
BGS
P4CNT (92h)
P4CNT.5–0
—
ACON (9Dh)
ACON.5
MROM
Merge ROM
—
ACON.4
BPME
Breakpoint Mode Enable
—
ACON.3
BROM
By-Pass ROM
—
ACON.2
SA
—
ACON.1–0
AM1–AM0
P5CNT (A2h)
P5CNT.2–0
—
C0C (A3h)
C0C.3
CRST
P6CNT (B2h)
P6CNT.5–0
—
MCON (C6h)
MCON.7–6
IDM1–IDM0
—
MCON.5
CAN
—
MCON.3–0
PDCE3–PDCE0
FUNCTION
Bandgap Select
Port 4 Pin Configuration Control Bits
Stack Address Mode
Address Mode Select Bits
Port 5 Pin Configuration Control Bits
CAN 0 Reset
Port 6 Pin Configuration Control Bits
Internal Memory Configuration Bits
CMA Data Memory Assignment
Program/Data-Chip Enables
COR (CEh)
COR.7
IRDACK
—
COR.4–3
C0BPR7–C0BPR6
IRDA Clock-Output Enable
—
COR.2–1
COD1–COD0
—
COR.0
CLKOE
CAN Clock-Output Enable
MCON1 (D6h)
MCON1.3–0
PDCE7–PDCE4
Program/Data Chip Enable
MCON2 (D7h)
MCON2.6–4
WPR2–WPR0
CAN 0 Baud Rate Prescale Bits
CAN Clock-Output Divide Bits
Write-Protect Range Bits
MCON2.3–0
WPE3–WPE0
WDCON (D8h)
WDCON.6
POR
Power-On Reset Flag
Write-Protect Enable Bits
—
WDCON.3
WDIF
Watchdog Interrupt Flag
—
WDCON.1
EWT
Watchdog Reset Enable
—
WDCON.0
RWT
Reset Watchdog Timer
EBS (E5h)
EBS.7
FPE
Flush Filter Failed-Packet Enable
—
EBS.4–0
BS4-BS0
Buffer Size Configuration Bits
MEMORY ARCHITECTURE
The DS80C400 incorporates four internal memory areas:
 256 Bytes of scratchpad (or direct) RAM
 8kB of SRAM for Ethernet MAC transmit/receive buffer memory
 1kB of SRAM configurable as various combinations of data memory and stack memory
 256 Bytes of RAM reserved for the CAN message centers
 64kB embedded ROM firmware
Up to 16MB of external code memory can be addressed through a multiplexed or demultiplexed 22-bit address
bus/8-bit data bus through eight available chip enables. Up to 4MB of external data memory can be accessed over
the same address/data buses through peripheral-enable signals. The DS80C400 also permits a 16MB merged
program/data memory map.
40 of 97
DS80C400 Network Microcontroller
ADDRESSING MODES
Three different addressing modes are supported, as selected by the AM1, AM0 bits in the address control (ACON;
9Dh) SFR.
AM1:0
ADDRESS MODE
00b
01b
1xb
16-bit (default when ROM disabled)
24-bit paged
24-bit contiguous (default when ROM enabled)
16-Bit Address Mode
The 16-bit address mode accesses memory in a similar manner as a traditional 8051. It is op-code compatible with
the 8051 microprocessor and identical to the byte and cycle count of the Maxim high-speed microcontroller family.
A device operating in this mode can access up to 64kB of program and data memory. The DS80C400 defaults to
this mode following any reset.
24-Bit Paged Address Mode
The 24-bit paged address mode retains binary-code compatibility with the 8051 instruction set, but adds one
machine cycle to the ACALL, LCALL, RET, and RETI instructions with respect to the Maxim high-speed
microcontroller family timing. This is transparent to standard 8051 compilers. Interrupt latency is also increased by
one machine cycle. In this mode, interrupt vectors are fetched from 0000xxh.
24-Bit Contiguous Address Mode
The 24-bit contiguous addressing mode uses a full 24-bit program counter, and all modified branching instructions
automatically save and restore the entire program counter. The 24-bit branching instructions such as ACALL,
AJMP, LCALL, LJMP, MOV DPTR, RET, and RETI instructions require an assembler, compiler, and linker that
specifically supports these features. The INC DPTR is lengthened by one cycle but remains byte-count compatible
with the standard 8051 instruction set.
Visit www.maxim-ic.com/microcontrollers for a list of tools that support the DS80C400.
Extended Address Generation
FUNCTION
ADDRESS BITS 23–16
ADDRESS BITS 15–8
ADDRESS BITS 7–0
DPXn
DPHn
DPLn
MXAX;EAh
P2;A0h
Ri
AP;9Ch
—
—
—
ESP;9Bh
SP;81h
MOVX Instructions Using DPTRn
MOVX Instructions Using @Ri
Addressing Program Memory In 24-Bit
Paged Mode
10-Bit Stack Pointer Mode
External Program Memory Addressing
Since the DS80C400 is not bound to the 8051’s traditional 16-bit address mode, on-chip hardware enhancements
were made to accommodate the larger memory interfaces associated with 24-bit addressing. The DS80C400
provides SFR bits to configure certain port pins as upper address lines and chip enables. The Port 4 control
register (P4CNT; 92h) and Port 6 control register (P6CNT; B2h) control the number of chip enables that are used
and the maximum amount of program memory that can be accessed per chip enable. Tables 3 and 4 illustrate
which port pins are converted to address lines or chip enables as a result of the P4CNT and P6CNT bit settings.
41 of 97
DS80C400 Network Microcontroller
Table 3. Extended Address Generation
P4CNT.5–3
P6.5
P6.4
P4.7
P4.6
P4.5
P4.4
000
001
010
011
100
101
110 or 111 (default)
I/O
I/O
I/O
I/O
I/O
I/O
A21
I/O
I/O
I/O
I/O
I/O
A20
A20
I/O
I/O
I/O
I/O
A19
A19
A19
I/O
I/O
I/O
A18
A18
A18
A18
I/O
I/O
A17
A17
A17
A17
A17
I/O
A16
A16
A16
A16
A16
A16
MAX MEMORY ACCESSIBLE
per CE
32kB (Note 1)
128kB
256kB
512kB
1MB
2MB (Note 2)
4MB (Note 3)
Table 4. Chip-Enable Generation
P6CNT.2–0
000 (default)
(Note 2)
100
101
110
111 (Note 2)
P6.3
PORT 6 PIN FUNCTION
P6.2
P6.1
P6.0
P4CNT.2–0
P4.3
PORT 4 PIN FUNCTION
P4.2
P4.1
P4.0
I/O
I/O
I/O
I/O
000
I/O
I/O
I/O
I/O
I/O
I/O
I/O
CE7
I/O
I/O
CE6
CE6
I/O
CE5
CE5
CE5
CE4
CE4
CE4
CE4
100
101
110
111 (default)
I/O
I/O
I/O
CE3
I/O
I/O
CE2
CE2
I/O
CE1
CE1
CE1
CE0
CE0
CE0
CE0
Note 1: Only 32kB of memory is accessible per chip enable for the P4CNT.5-3 = 000b setting, which means at least two chip enables are
needed to address the standard 16-bit (0–FFFFh) address range.
Note 2: When the ROM is enabled, the default memory map is reconfigured to 2MB per CE, P4CNT.5-3 = 101b, and CE4–CE7 are enabled,
P6CNT.2-0 = 111b.
Note 3: The default P4CNT.5-3 = 111b setting (4MB accessible per CE) requires only four chip enables to access the maximum 24-bit (0–
FFFFFFh) address range.
External Data Memory Addressing
Using a similar implementation as was used to expand program memory access, the DS80C400 allows up to 4MB
of data memory access through four peripheral chip enables (PCE). The Port 5 control register (P5CNT; A2h) and
Port 6 control register (P6CNT; B2h) designate the number of peripheral chip enables and the maximum amount of
addressable data memory per peripheral chip enable. Table 5 shows which port pins are converted to peripheral
chip enables, along with the maximum memory accessible through each peripheral chip enable for P5CNT, P6CNT
bit settings.
Table 5. Peripheral Chip-Enable Generation
P5CNT.2–0
000 (default)
100
101
110
111
P5.7
I/O
I/O
I/O
I/O
PCE3
P5.6
I/O
I/O
I/O
PCE2
PCE2
P5.5
I/O
I/O
PCE1
PCE1
PCE1
P5.4
I/O
PCE0
PCE0
PCE0
PCE0
P6CNT.5–3
000 (default)
001
010
011
100
MAX MEMORY ACSESSIBLE per PCE
32kB
128kB
256kB
512kB
1MB
Demultiplexed External Memory Addressing
On power-up or following any reset, the DS80C400 defaults to the traditional 8051 external memory interface, with
the address MSB presented on Port 2 and the address LSB and data multiplexed on Port 0. The multiplexed mode
requires an external latch to demultiplex the address LSB and data. The DS80C400 provides an external pin (MUX)
that, when pulled high during a power-on reset, demultiplexes the address LSB and data. If demultiplexed mode is
enabled, the address LSB is provided on Port 7 and the data on Port 0. At the expense of consuming Port 7,
demultiplexed mode eliminates the external demultiplexing latch and the delay element associated with the latch. In
some cases, the removal of this timing delay allows use of slower, less expensive external memory devices.
Table 6 shows pin assignments for the multiplexed (traditional 8051) and demultiplexed external addressing
modes.
42 of 97
DS80C400 Network Microcontroller
Table 6. External Memory Addressing Pin Assignments
ADDRESS
SIGNAL
A21
A20
A19
A18
A17
A16
A15–A8
A7–A0
MULTIPLEXED (MUX = 0)
P6.5
P6.4
P4.7
P4.6
P4.5
P4.4
P2.7–P2.0
P0.7–P0.0
DEMULTIPLEXED (MUX = 1)
P6.5
P6.4
P4.7
P4.6
P4.5
P4.4
P2.7–P2.0
P7.7–P7.0
DATA
D7–D0
P0.7–P0.0
P0.7–P0.0
CE7
CE6
CE5
CE4
CE3
CE2
CE1
CE0
PCE3
PCE2
PCE1
PCE0
P6.3
P6.2
P6.1
P6.0
P4.3
P4.2
P4.1
P4.0
P5.7
P5.6
P5.5
P5.4
P6.3
P6.2
P6.1
P6.0
P4.3
P4.2
P4.1
P4.0
P5.7
P5.6
P5.5
P5.4
CHIP ENABLES
PERIPHERAL CHIP
ENABLES
Combined Program/Data Memory Access
The DS80C400 can be configured to allow data memory access (MOVX) to the program memory area. This feature
might be useful, for example, when modifying lookup tables or supporting in-application programming of code
space. Setting any of the PDCE7-4 (MCON1.3-0) or PDCE3-0 (MCON.3-0) bits enables combined program/data
memory access and causes the corresponding chip-enable (CE) signal to function for both MOVC and MOVX
operations. When combined program/data memory access is enabled, the peripheral chip-enable (PCE) signals
previously assigned to that data memory space are disabled. Write access to combined program and data memory
blocks is controlled by the WR signal, and read access is controlled by the PSEN signal. This feature is especially
useful if the design achieves in-system reprogrammability through external flash memory, in which a single device
is accessed through both MOVC instructions (program fetch) and MOVX write operations (updates to code
memory). Figure 1 demonstrates how setting PDCE bits can alter external memory data access.
When combined program/data memory access is enabled, there is the potential to inadvertently modify code that a
user meant to leave fixed. For this reason, the DS80C400 provides the ability to write protect the first 0–16kB of
memory accessible through each of the chip enables CE3, CE2, CE1, and CE0. The write-protection feature for
each chip enable is invoked by setting the appropriate WPE3–0 (MCON2.3-0) bit. The protected range is defined
by the WPR2–0 (MCON2.6–4) bit settings as shown in Table 7. Any MOVX instructions attempting to write to a
protected area are disallowed and set the write-protected interrupt flag (WPIF–MCON2.7), causing a write-protect
interrupt if enabled.
Table 7. Write-Protection Range
MCON2.6–4
000
001
010
011
100
101
110
111
RANGE PROTECTED (kB)
0 to 2
0 to 4
0 to 6
0 to 8
0 to 10
0 to 12
0 to 14
0 to 16
43 of 97
DS80C400 Network Microcontroller
Figure 1. Example External Memory Map—Merged Program/Data
= 2M x 8
CE6
= 2M x 8
CE5
= 2M x 8
CE4
= 2M x 8
CE3
= 2M x 8
CE2
=2M x 8
CE1
=2M x 8
CE0
PROGRAM
MEMORY
CE7
NONADDRESSABLE
CE7
DATA
MEMORY
= 1M x 8
PCE2
= 1M x 8
PCE1
= 1M x 8
PCE0
= 1M x 8
PDCE0 = 1
=2M x 8
BEFORE
DATA
MEMORY
= 2M x 8
CE6
= 2M x 8
CE5
= 2M x 8
CE4
= 2M x 8
PDCE3 = 1
PCE3
PROGRAM/
DATA
MEMORY
NONADDRESSABLE
PROGRAM
MEMORY
CE3
CE2
= 2M x 8
CE1
= 2M x 8
CE0
= 2M x 8
PCE3
= 1M x 8
PCE2
= 1M x 8
= 2M x 8
AFTER
Enhanced Quad Data Pointers
The DS80C400 offers enhanced features for accelerating the access and movement of data. It contains four data
pointers (DPTR0, DPTR1, DPTR2, and DPTR3), in comparison to the single data pointer offered on the original
8051, and allows the user to define, for each data pointer, whether the INC DPTR instruction increments or
decrements the selected pointer. Also, realizing that many data accesses occur in large contiguous blocks, the
DS80C400 can be configured to automatically increment or decrement a data pointer on execution of certain
instructions. This improvement greatly speeds access to consecutive pieces of data since hardware can now
accomplish a task (advancing the data pointer) that previously required software execution time. Finally, each pair
of data pointers (DPTR0, DPTR1 or DPTR2, DPTR3) can be configured for an auto-toggle mode. When placed into
this mode, certain data pointer-related instructions toggle the active data-pointer selection to the other pointer in the
pair. Enabling the auto-toggle feature, with one pointer to source data and a second pointer to destination data,
greatly speeds the copying of large data blocks.
DPTR0 is located at the same address as the original 8051 data pointer, allowing the DS80C400 to execute
standard 8051 code with no modifications. The registers making up the second, third, and fourth data pointers are
located at SFR address locations not used in the original 8051. To access the extended 24-bit address range
supported by the DS80C400, a third, high-order byte (DPXn) has been added to each pointer so that each data
pointer is now composed of the SFR combination DPXn+DPHn+DPLn. Table 8 summarizes the SFRs that make
up each data pointer.
44 of 97
DS80C400 Network Microcontroller
Table 8. Data Pointer SFR Locations
DATA POINTER
DPTR0
DPTR1
DPTR2
DPTR3
DPX+DPH+DPL COMBINATION
DPX (93h) + DPH (83h) + DPL (82h)
DPX1 (95h) + DPH1 (85h) + DPL1 (84h)
DPX2 (EBh) + DPH2 (F3h) + DPL2 (F2h)
DPX3 (EDh) + DPH3 (F5h) + DPL3 (F4h)
The active data pointer is selected with the data pointer select bits SEL1 (DPS.3) and SEL (DPS.0). For the SEL1
and SEL bits, the 00b state selects DPTR0, 01b selects DPTR1, 10b selects DPTR2, and 11b selects DPTR3. Any
instructions that reference the DPTR (i.e., MOVX A, @DPTR) use the data pointer selected by the SEL1, SEL bitpair combination. To allow for code compatibility with previous dual data pointer microcontrollers, the bits adjacent
to SEL are not implemented so that the INC DPS instruction can still be used to quickly toggle between DPTR0 and
DPTR1 or between DPTR2 and DPTR3.
Unlike the standard 8051, the DS80C400 has the ability to decrement as well as increment the data pointers
without additional instructions. Each data pointer (DPTR0, DPTR1, DPTR2, DPTR3) has an associated control bit
(ID0, ID1, ID2, ID3) that determines whether the INC DPTR operation results in an increment or decrement of the
pointer. When the active data pointer ID (increment/decrement) control bit is clear, the INC DPTR instruction
increments the pointer, whereas a decrement occurs if the active pointer’s ID bit is set when the INC DPTR
instruction is performed.
ID0 = DPS.6
ID1 = DPS.7
ID2 = DPS1.6
ID3 = DPS1.7
Another useful feature of the device is its ability to automatically switch the active data pointer after certain DPTRbased instructions are executed. This feature can greatly reduce the software overhead associated with data
memory block moves, which toggle between the source and destination registers. The auto-toggle feature does not
toggle between all four data pointers, nor does it allow the user to select which data pointers to toggle between.
When the toggle select bit (TSL;DPS.5) is set to 1, the SEL bit (DPS.0) is automatically toggled every time one of
the DPTR instructions below is executed. Thus, depending upon the state of the SEL1 bit (DPS.3), the active data
pointer toggles the DPTR0, DPTR1 pair or the DPTR2, DPTR3 pair.
Auto-Toggle (if TSL = 1)
INC DPTR
MOV DPTR, #data16
MOV DPTR, #data24
MOVC A, @A+DPTR
MOVX A, @DPTR
MOVX @DPTR, A
As a brief example, if TSL is set to 1, then both data pointers can be updated with two INC DPTR instructions.
Assume that SEL1 = 0 and SEL = 0, making DPTR0 the active data pointer. The first INC DPTR increments
DPTR0 and toggles SEL to 1. The second instruction increments DPTR1 and toggles SEL back to 0.
INC DPTR
INC DPTR
As a further enhancement, the DS80C400 provides the ability to automatically increment/decrement the active data
pointer after certain DPTR-based instructions are executed. Copying large blocks of data generally requires that
the source and destination pointers index byte-by-byte through their respective data ranges. The traditional method
for incrementing each pointer is by using the INC DPTR instruction. When the auto-increment/decrement bit
(AID:DPS.4) is set to 1, the active data pointer is automatically incremented or decremented every time one of the
DPTR instructions below is executed.
45 of 97
DS80C400 Network Microcontroller
Auto-Increment/Decrement (if AID = 1)
MOVC A, @A+DPTR
MOVX A, @DPTR
MOVX @DPTR, A
When used in conjunction, the auto-toggle and auto-increment/decrement features can produce very fast and
efficient routines for copying or moving data. For example, suppose you want to copy three bytes of data from a
source location (pointed to by DPTR2) to a destination location (pointed to by DPTR3). Assuming that DPTR2 is
the active pointer (SEL1 = 1, SEL = 0), with TSL = 1 and AID = 1, the instruction sequence below copies the three
bytes:
MOVX
MOVX
MOVX
MOVX
MOVX
MOVX
A, @DPTR
@DPTR, A
A, @DPTR
@DPTR, A
A, @DPTR
@DPTR, A
Stretch Memory Cycles
The DS80C400 allows user-application software to select the number of machine cycles it takes to execute a
MOVX instruction, allowing access to both fast and slow off-chip data memory and/or peripherals without glue
logic. High-speed systems often include memory-mapped peripherals such as LCDs or UARTs with slow access
times, so it may not be necessary or desirable to access external devices at full speed. The microprocessor can
perform a MOVX instruction in as little as two machine cycles or as many as 12 machine cycles. Accesses to
internal MOVX SRAM always use two cycles. Note that stretch cycle settings affect external MOVX memory
operations only and there is no way to slow the accesses to program memory other than to use a slower crystal (or
external clock).
External MOVX timing is governed by the selection of 0-to-7 stretch cycles, controlled by the MD2–MD0 SFR bits in
the clock control register (CKCON.2–0). A stretch of 0 results in a 2-machine cycle MOVX instruction. A stretch of 7
results in a MOVX of 12 machine cycles. Software can dynamically change the stretch value depending on the
particular memory or peripheral being accessed. The default of one stretch cycle allows the use of commonly
available SRAMs without dramatically lengthening the memory access times.
Stretch cycle settings affect external MOVX timing in three gradations. Changing the stretch value from 0 to 1 adds
an additional clock cycle each to the data setup and hold times. Stretch values of 2 and 3 each stretch the WR or
RD signal by an additional machine cycle. When a stretch value of 4 or above is selected, the interface timing
changes dramatically to allow for very slow peripherals. First, the ALE signal is lengthened by one machine cycle.
This increases the address setup time into the peripheral by this amount. Next, the address is held on the bus for
one additional machine cycle, increasing the address hold time by this amount. The WR and RD signals are then
lengthened by a machine cycle. Finally, during a MOVX write the data is held on the bus for one additional machine
cycle, thereby increasing the data hold time by this amount. For every stretch value greater than 4, the setup and
hold times remain constant, and only the width of the read or write signal is increased. These three gradations are
reflected in the AC Electrical Characteristics section, where the eight MOVX timing specifications are represented
by only three timing diagrams.
The reset default of one stretch cycle results in a three-cycle MOVX for any external access. Therefore, the default
off-chip RAM access is not at full speed. This is a convenience to existing designs that use slower RAM. When
maximum speed is desired, software should select a stretch value of 0. When using very slow RAM or peripherals,
the application software can select a larger stretch value.
The specific timing of MOVX instructions as a function of stretch settings is provided in the Electrical Specifications
section of this data sheet. As an example, Table 9 shows the read and write strobe widths corresponding to each
stretch value.
46 of 97
DS80C400 Network Microcontroller
Table 9. Data Memory Cycle Stretch Values
MD2
MD1
MD0
STRETCH
VALUE
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0 (Note 1)
1 (Note 2)
2
3
4
5
6
7
MOVX
MACHINE
CYCLES
2
3
4
5
9
10
11
12
APPROXIMATE RD, WR PULSE WIDTH
(IN OSCILLATOR CLOCKS)
(4X/2X = 1
(4X/2X = 0
(4X/2X = X
(4X/2X = X
CD1:0 = 00)
CD1:0 = 00)
CD1:0 = 10)
CD1:0 = 11)
0.5 tCLK
1 tCLK
2 tCLK
512 tCLK
1 tCLK
2 tCLK
4 tCLK
1024 tCLK
2 tCLK
4 tCLK
8 tCLK
2048 tCLK
3 tCLK
6 tCLK
12 tCLK
3072 tCLK
4 tCLK
8 tCLK
16 tCLK
4096 tCLK
5 tCLK
10 tCLK
20 tCLK
5120 tCLK
6 tCLK
12 tCLK
24 tCLK
6144 tCLK
7 tCLK
14 tCLK
28 tCLK
7168 tCLK
Note 1: All internal MOVX operations execute at the 0 stretch setting.
Note 2: Default stretch setting for external MOVX operations following reset, but reset before execution of ROM startup code.
Internal MOVX SRAM
The DS80C400 contains 9kB of SRAM that is physically divided into a 1kB block and an 8kB block. The 1kB block
can be used to support the extended stack-pointer function or can be used as general-purpose MOVX data
memory. The 8kB block is used by the Ethernet MAC as frame-buffer memory for incoming or outgoing packet data
and can, at the same time, be accessed by the DS80C400 as MOVX data memory. While the MAC is in use,
special care should be taken by user software to prevent undesirable MOVX writes from corrupting frame-buffer
memory. The address mapping of the 1kB block and the 8kB block are governed by the internal data-memory
configuration bits (IDM1, IDM0) in the memory control register (MCON;C6h). Note that when the SA bit (ACON.2)
is set, 1kB of the MOVX data memory is accessed by the 10-bit expanded stack pointer. Changing the IDM1:0
configuration bits while SA = 1 does not disrupt the extended stack-pointer function. Internal MOVX memory
accesses do not generate WR or RD strobes.
The DS80C400 contains an additional 256 Bytes of internal SRAM that is used to configure and operate the 15
CAN-controller message centers. The address location of this 256-Byte block is determined by the CAN datamemory assignment bit (CMA) in the memory control register (MCON; C6h).
Table 10. Internal MOVX SRAM Configuration
IDM1
IDM0
CMA
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
8kB BLOCK
(MAC/MOVX DATA)
00E000h–00FFFFh
00E000h–00FFFFh
000000h–001FFFh
000000h–001FFFh
FFE000h–FFFFFFh
FFE000h–FFFFFFh
1kB BLOCK
(STACK/MOVX DATA)
00DC00h–00DFFFh
00DC00h–00DFFFh
002000h–0023FFh
002000h–0023FFh
FFDC00h–FFDFFFh
FFDC00h–FFDFFFh
256-BYTE
(CAN DATA MEMORY)
00DB00h–00DBFFh
FFDB00h–FFDBFFh
00DB00h–00DBFFh
FFDB00h–FFDBFFh
00DB00h–00DBFFh
FFDB00h–FFDBFFh
Extended Stack Pointer
The DS80C400 supports both the traditional 8-bit and an extended 10-bit stack pointer that improves the
performance of large programs written in high-level languages such as C. To enable the 10-bit stack pointer, set
the stack-address mode bit, SA (ACON.2). The bit is cleared following a reset, forcing the device to use an 8-bit
stack located in the scratchpad RAM area. When the SA bit is set, the device addresses up to 1kB of internal
MOVX memory for stack purposes. The 10-bit stack pointer address is generated by concatenating the lower two
bits of the extended stack pointer (ESP;9Bh) and the traditional 8051 stack pointer (SP;81h).
On-Chip Arithmetic Accelerator
An on-chip math accelerator allows the microcontroller to perform 32-bit and 16-bit multiplication, division, shifting,
and normalization using dedicated hardware. Math operations are performed by sequentially loading three special
registers. The mathematical operation is determined by the sequence in which three dedicated SFRs (MA, MB, and
MCNT0) are accessed, eliminating the need for a special step to choose the operation. The normalize function
47 of 97
DS80C400 Network Microcontroller
facilitates the conversion of 4-Byte unsigned binary integers into floating point format. Table 11 shows the
operations supported by the math accelerator and their time of execution.
Table 11. Arithmetic Accelerator Execution Times
OPERATION
32-Bit/16-Bit Divide
16-Bit/16-Bit Divide
16-Bit/16-Bit Multiply
32-Bit Shift Left/Right
32-Bit Normalize
RESULT
32-Bit Quotient, 16-Bit Remainder
16-Bit Quotient, 16-Bit Remainder
32-Bit Product
32-Bit Result
32-Bit Mantissa, 5-Bit Exponent
EXECUTION TIME
36 tCLCL
24 tCLCL
24 tCLCL
36 tCLCL
36 tCLCL
Table 12 demonstrates the procedure to perform mathematical operations using the hardware math accelerator.
The MA and MB registers must be loaded and read in the order shown for proper operation, although accesses to
any other registers can be performed between accesses to the MA or MB registers. An access to the MA, MB, or
MC registers out of sequence corrupt the operation, requiring the software to clear the MST bit to restart the math
accelerator state machine. See the descriptions of the MCNT0 and MCNT1 SFRs for details about how the shift
and normalize functions operate.
Table 12. Arithmetic Accelerator Sequencing
DIVIDE (32/16 or 16/16)
Load MA with dividend LSB.
Load MA with dividend LSB + 1*.
*
Load MA with dividend LSB + 2 .
Load MA with dividend MSB.
Load MB with divisor LSB.
Load MB with divisor MSB.
Poll the MST bit until cleared.
(9 machine cycles for 32-bit numerator)
(6 machine cycles for 16-bit numerator)
Read MA to retrieve the quotient MSB.
Read MA to retrieve the quotient LSB + 2*
Read MA to retrieve the quotient LSB + 1*
Read MA to retrieve the quotient LSB.
Read MB to retrieve the remainder MSB.
Read MB to retrieve the remainder LSB.
MULTIPLY (16 x 16)
Load MB with multiplier LSB.
Load MB with multiplier MSB.
Load MA with multiplicand LSB.
Load MA with multiplicand MSB.
Poll the MST bit until cleared (6 machine cycles).
Read MA for product MSB.
Read MA for product LSB + 2.
Read MA for product LSB + 1.
Read MA for product LSB.
SHIFT RIGHT/LEFT
Load MA with data LSB.
Load MA with data LSB + 1.
Load MA with data LSB + 2.
Load MA with data MSB.
Configure MCNT0/MCNT1 registers as required.
Poll the MST bit until cleared (9 machine cycles).
Read MA for result MSB.
Read MA for result LSB + 2.
Read MA for result LSB + 1.
Read MA for result LSB.
NORMALIZE
Load MA with data LSB.
Load MA with data LSB + 1.
Load MA with data LSB + 2.
Load MA with data MSB.
Configure MCNT0.4–0 = 00000b.
Poll the MST bit until cleared (9 machine cycles).
Read MA for mantissa MSB.
Read MA for mantissa LSB + 2.
Read MA for mantissa LSB + 1.
Read MA for mantissa LSB.
Read MCNT0.4–MCNT0.0 for exponent.
*Not performed for 16-bit numerator.
48 of 97
DS80C400 Network Microcontroller
40-Bit Accumulator
The accelerator also incorporates an automatic accumulator function, permitting the implementation of multiplyand-accumulate and divide-and-accumulate functions without any additional delay. Each time the accelerator is
used for a multiply or divide operation, the result is transparently added to a 40-bit accumulator. This can greatly
increase speed of DSP and other high-level math operations.
The accumulator can be accessed any time the multiply/accumulate status flag (MCNT1;D2h) is cleared. The
accumulator is initialized by performing five writes to the multiplier C register (MC;D5h), LSB first. The 40-bit
accumulator can be read by performing five reads of the multiplier C register, MSB first.
Ethernet Controller
The DS80C400 incorporates a 10/100Mbps Ethernet controller, which supports the protocol requirements for
operating an Ethernet/IEEE 802.3-compliant PHY device. It provides receive, transmit, and flow control
mechanisms through a media-independent interface (MII), which includes a serial management bus for configuring
external PHY devices. The MII can be configured to operate in half-duplex or full-duplex mode at either 10Mbps or
100Mbps, or can support 10Mbps ENDEC mode operation. The system clock (external clock source after internal
multiplication or division) must be a minimum of 25MHz for use of the Ethernet 100Mbps mode.
For half-duplex mode operation, the DS80C400 shares the Ethernet physical media with other stations on the
network. The DS80C400 follows the IEEE 802.3 carrier-sense multiple-access with collision detection (CSMA/CD)
method for accessing the physical media. The MAC waits until the physical carrier is idle before attempting a
transmission. Having multiple stations on the network results in the possibility of transmissions from different
stations colliding. When a collision is detected, the MAC waits some number of time slots (according to an internal
back-off timer) before attempting retransmission. Unless instructed otherwise, the MAC automatically attempts to
retransmit collided frames up to 16 times before aborting the transmit frame. As a means of flow control when
receiving data, the MAC uses a back-pressure scheme, transmitting a jamming signal to force collisions on
incoming frames transmitted by other stations. Using this back-pressure scheme gives the DS80C400 control of
the network or time to free up needed receive data buffers.
For full-duplex mode operation, the physical media connects the DS80C400 directly to only one other station,
allowing simultaneous transmit and receive activity between the two without risk of collision. Hence, no mediaaccess method (i.e., CSMA/CD) needs to be used. For full-duplex operation, the flow control mechanism is the
PAUSE control frame. When needing time to free additional receive data buffers, the DS80C400 can initiate a
PAUSE control frame, requesting that the other station suspend transmission attempts for a specified number of
time slots.
Figure 2. Ethernet Controller Block Diagram
POWER MANAGEMENT
BLOCK
CSR REGISTERS
EXTERNAL
PHY(s)
MII I/O BLOCK
(TRANSMIT,
RECEIVE, AND
FLOW CONTROL)
ADDRESS CHECK
BLOCK
Tx/Rx BUFFER
MEMORY
(8kB)
MAC HOST INTERFACE
MII MANAGEMENT
BLOCK
<SERIAL
INTERFACE BUS TO
EXTERNAL PHY(s)>
DS80C400
CPU
BCU
DS80C400 ON-CHIP ETHERNET CONTROLLER
NOTE: WHEN CONNECTING THE DS80C400 TO AN EXTERNAL PHY, DO NOT CONNECT THE RSTOL TO THE RESET OF THE PHY. DOING SO MAY
DISABLE THE ETHERNET TRANSMIT.
49 of 97
DS80C400 Network Microcontroller
Buffer Control Unit
The buffer control unit (BCU) serves as the central controller of all DS80C400 Ethernet activity. The BCU regulates
CPU read/write activity to the Ethernet controller blocks through a series of SFRs: BCU control (BCUC; E7h), BCU
data (BCUD; E6h), CSR address (CSRA; E4h), and CSR data (CSRD; E3h). These SFRs allows the CPU to issue
commands to the BCU, exchange packet size/location information with the BCU, configure the on-chip Ethernet
MAC, and even communicate with external PHYs through the MII serial-management bus.
Table 13 outlines the commands that can be issued through the BCUC register. Prior to issuing a write (1000b) or
read (1001b) CSR register command, the CSRA SFR must be configured to address a valid CSR register. For
each CSR register write, the CSRD SFR must be loaded with the data to be written prior to issuing the write
command, whereas on a read, CSRD returns the CSR register data following the read command. Table 14 lists the
CSR register addresses and functions.
Table 13. Buffer Control Unit Commands
COMMAND
(BCUC.3:BCUC.0)
0000
0010
0011
0100
0101
0110
1000
1001
1100
1101
Other
OPERATION
No Operation (default)
Invalidate Current Receive Packet
Flush Receive Buffer
Transmit Request (normal)
Transmit Request (disable padding)
Transmit Request (disable CRC)
Write CSR Register
Read CSR Register
Enable Sleep Mode
Disable Sleep Mode
Reserved
Table 14. CSR Registers
CSR REGISTER ADDRESS
(CSRA)
00h
04h
08h
0Ch
10h
14h
18h
1Ch
20h
24h
28h
2Ch
Other
FUNCTION
MAC Control
Ethernet MAC Physical Address [47:32]
Ethernet MAC Physical Address [31:0]
Multicast Address Hash Table [63:32]
Multicast Address Hash Table [31:0]
MII Address
MII Data
Flow Control
VLAN1 Tag
VLAN2 Tag
Wake-Up Frame Filter
Wake-Up Events Control and Status
Reserved
The BCU is responsible for coordinating and reporting status for all data-packet transactions between the Ethernet
MAC and the 8kB packet-buffer memory. The size of the transmit and receive buffers within the 8kB packet-buffer
memory is user-configurable through the EBS (E5h) register. During transmit and receive operations, the BCU
operates according to the user-defined buffer allocation and tracks consumption of receive buffer memory so that a
receive-buffer-full condition can be signaled.
For a receive operation, the BCU first must assess whether there are any open pages in receive buffer memory to
accommodate an incoming packet. If there are not open pages, the receive-buffer-full (RBF; EBS.6) flag is set.
Until the RBF condition is cleared, all incoming frames are missed. If receive buffer memory has open pages, the
received data is stored in the first open page starting at byte offset 4, leaving the first 4 bytes open for packet status
reporting. Receive packets requiring multiple pages are stored in consecutive pages. Note that the receive buffer
operates as a circular queue, with page 0 being the consecutive page to follow the final (n - 1) receive buffer page.
The BCU stores incoming data to receive buffer memory until the transaction is complete or until the reception is
50 of 97
DS80C400 Network Microcontroller
aborted. The BCU incorporates a 31 x 8 first-in-first-out receive packet register (receive FIFO) so that the CPU can
access information for the next receive packet in queue. Upon reception of each valid packet into receive buffer
memory, the BCU writes a receive status word into the first word of the receive packet starting page, updates the
receive FIFO, and notifies the CPU by setting an interrupt flag. The CPU can access the receive FIFO by reading
the BCUD SFR. Bits 4–0 of the data read from BCUD contain the starting page address and bits 7, 6, 5 reflect the
number of pages occupied by the packet.
For a transmit operation, the tasks performed by the BCU are similar. The CPU first provides size/location
information of the transmit packet to the BCU. This is accomplished by three consecutive writes to the BCUD SFR.
The first write specifies the MSB of the 11-bit byte count for the transmit packet, the second gives the LSB of the
11-bit byte count, and the third provides the starting page address for the packet. Note that at page 31 of the
transmit buffer, the next consecutive page is page (n). The CPU issues a transmit request to the BCU, which then
communicates this request to the MAC. Once started, the BCU reads data from transmit buffer memory and feeds
the data to the MAC for presentation on the MII. This process continues until the transaction is complete or the
transmission is aborted. The BCU then writes a transmit status word back to transmit buffer memory and notifies
the CPU by setting the interrupt flag. Transmit buffer management should be handled by the application code.
Command/Status (CSR) Registers
The CSR registers are essential in defining the operational characteristics of the Ethernet controller. The CSR
registers contain the following key items:







MAC physical address
Transmit, receive, and flow control settings for the MAC
Multicast hash table used by the address check block
Filter mode and good/bad frame controls for the address check block
VLAN tag identifiers
Wake-up frame filter
Register interface for serial MII PHY management bus
Each CSR register is 32-bits wide and is accessible using the BCUC, CSRA, CSRD SFR interface described in the
Buffer Control Unit section. To program a CSR register, the application code must provide data (CSRD) and
address (CSRA) for the target register before issuing the ‘Write CSR Register’ command to the BCU. When
performing a CSR register read, the application code provides the address (CSRA), issues the ‘Read CSR
Register’ command to the BCU, and then may unload the data (CSRD). The sequences below illustrate the correct
procedures for writing and reading the CSR registers.
CSR Register Write
Load CSRD with MSB of 32-bit word to be written.
Load CSRD with LSB + 2 of the 32-bit word to be written.
Load CSRD with LSB + 1 of the 32-bit word to be written.
Load CSRD with LSB of the 32-bit word to be written.
Load CSRA with address of the CSR register to be written.
Issue the ‘Write CSR Register’ command to the BCU by writing BCUC.3–BCUC.0 = 1000b.
CSR Register Read
Load CSRA with address of the CSR register to be read.
Issue the ‘Read CSR Register’ command to the BCU by writing BCUC.3–BCUC.0 = 1001b.
Wait until the BCU busy bit (BCUC.7) = 0.
Unload CSRD for the MSB of the 32-bit word.
Unload CSRD for the LSB + 2 of the 32-bit word.
Unload CSRD for the LSB + 1 of the 32-bit word.
Unload CSRD for the LSB of the 32-bit word.
51 of 97
DS80C400 Network Microcontroller
Each CSR register is documented as follows:
CSR Register:
Register Address:
MAC Control
00h
Bit Names:
31
23
15
7
—
RA
BLE
DRO
OM[1:0]
HO
—
HP
BLOMT[1:0]
DC
HBD
F
LCC
—
PS
PM
DBF
TE
—
PR
DRTY
RE
—
IF
—
—
—
PB
ASTP
—
24
16
8
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
24
16
8
0
Reset State:
31
23
15
7
0
0
0
0
0
0
0
0
0
0
0
0
RA, Receive All. This bit overrides the flush-filter failed-packet function if that function has been enabled
(EBS.7 = 1).
0 = default frame handling (default)
1 = all error-free frames are received with packet filter bit set (= 1) in the receive status word
BLE, Big-/Little-Endian Mode
0 = data buffers are operated in little-endian mode (default)
1 = data buffers are operated in big-endian mode
HBD, Heart-Beat Disable. This bit is only useful in ENDEC mode and has no effect on MII mode operation.
0 = heart-beat signal quality-generator function enabled (default)
1 = heart-beat signal quality-generator function is disabled
PS, Port Select
0 = MII mode (default)
1 = ENDEC mode
DRO, Disable Receive Own. This bit should always be cleared to a logic 0 for full-duplex operation and any
loopback operating modes other than “normal mode.”
0 = MAC receives all packets given by the PHY (default)
1 = MAC disables reception of frames during frame transmission (TX_EN = 1)
OM[1:0], Loopback Operating Mode
00 = normal mode, no loopback (default)
01 = internal loopback through MII
10 = external loopback through PHY
11 = reserved
F, Full-Duplex Mode
0 = half-duplex mode (default)
1 = full-duplex mode
PM, Pass All Multicast
0 = multicast frames filtered according to current multicast filter mode (default)
1 = pass all multicast frames; filter-fail bit is reset (= 0) for all multicast frames received
PR, Promiscuous Mode
0 = promiscuous mode disabled
1 = promiscuous mode enabled (default)
52 of 97
DS80C400 Network Microcontroller
IF, Inverse Filtering
0 = inverse filtering disabled (default)
1 = inverse filtering by the address check block enabled
PB, Pass Bad Frames
0 = packet filter bit in the receive status word is set (= 1) only when error-free frames received (default)
1 = packet filter bit in the receive status word is set (= 1) for frames that pass the destination address filter even
when they contain errors. Promiscuous mode should always be used when this bit is set.
HO, Hash-Only Filtering Mode
This bit should only be set when HP = 1.
0 = filter unicast frames according to filter mode configuration (default)
1 = hash filtering of unicast and multicast frames by the address check block
HP, Hash/Perfect Filtering Mode
0 = perfect filtering by the address check block for unicast and multicast frames (default)
1 = hash filtering by the address check block for multicast frames and perfect filtering of unicast frames
LCC, Late Collision Control
0 = transmission is aborted if a late collision is encountered (default)
1 = allows frame retransmission attempts even when a late collision is encountered
DBF, Disable Broadcast Frames
0 = packet filter bit in the receive status word is set (= 1) for each broadcast frame received (default)
1 = packet filter bit in the receive status word is reset (= 0) for each broadcast frame received
DRTY, Disable Retry
0 = MAC attempts to transmit a frame 16 times before signaling a retry error (default)
1 = MAC attempts to transmit a frame only once before signaling a retry error
ASTP, Automatic Pad Stripping
0 = receive frames are transferred to the BCU without modification (default)
1 = zero padding and CRC are stripped for receive frames, which specify a data length less than 46 Bytes
BOLMT[1:0], Back-Off Limit. The back-off protocol requires that the MAC wait some number of time slots (512bits
/ time slot) before rescheduling a transmission attempt. A 10-bit free-running counter is used to generate this backoff delay. The BOLMT[1:0] bits select the number of bits to be used from the 10-bit counter.
00 = 10 bits (0 to 1024 time slots, default)
01 = 8 bits (0 to 256 time slots)
10 = 4 bits (0 to 16 time slots)
11 = 1 bit (none or 1 time slot)
DC, Deferral Check
0 = MAC can defer indefinitely while waiting to transmit (default)
1 = MAC aborts a transmission attempt if it has deferred for more than 24,288 consecutive bit times
TE, Transmitter Enable
0 = transmitter disabled (default)
1 = transmitter enabled
RE, Receiver Enable
0 = receiver disabled (default)
1 = receiver enabled
53 of 97
DS80C400 Network Microcontroller
CSR Register:
Register Address:
MAC Address High
04h
Bit Names:
31
23
15
7
—
—
—
—
—
—
—
—
—
—
PADR [47:40]
PADR [39:32]
—
—
—
—
—
—
24
16
8
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
24
16
8
0
Reset State:
31
23
15
7
0
0
1
1
0
0
1
1
PADR [47:32]m MAC Physical Address [47:32]. These two bytes represent the 16 most significant bits of the
MAC physical address.
CSR Register:
Register Address:
MAC Address Low
08h
Bit Names:
31
23
15
7
PADR [31:24]
PADR [23:16]
PADR [15:8]
PADR [7:0]
24
16
8
0
Reset State:
31
23
15
7
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
24
16
8
0
PADR [31:0], MAC Physical Address [31:0]. These four bytes represent the 32 least significant bits of the MAC
physical address.
54 of 97
DS80C400 Network Microcontroller
CSR Register:
Register Address:
Multicast Address High
0Ch
Bit Names:
31
23
15
7
HT[63]
HT[55]
HT[47]
HT[39]
HT[62]
HT[54]
HT[46]
HT[38]
HT[61]
HT[53]
HT[45]
HT[37]
HT[60]
HT[52]
HT[44]
HT[36]
HT[59]
HT[51]
HT[43]
HT[35]
HT[58]
HT[50]
HT[42]
HT[34]
HT[57]
HT[49]
HT[41]
HT[33]
HT[56]
HT[48]
HT[40]
HT[32]
24
16
8
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
0
0
0
24
16
8
0
Reset State:
31
23
15
7
0
0
0
0
HT [63:32], Hash Table [63:32]. These bits represent the upper 32 bits of the 64-bit hash table that are used for
hash table filtering. The multicast hash-filtering mode is detailed later in the data sheet.
CSR Register:
Register Address:
Multicast Address Low
10h
Bit Names:
31
23
15
7
HT[31]
HT[23]
HT[15]
HT[7]
HT[30]
HT[22]
HT[14]
HT[6]
HT[29]
HT[21]
HT[13]
HT[5]
HT[28]
HT[20]
HT[12]
HT[4]
HT[27]
HT[19]
HT[11]
HT[3]
HT[26]
HT[18]
HT[10]
HT[2]
HT[25]
HT[17]
HT[9]
HT[1]
HT[24]
HT[16]
HT[8]
HT[0]
24
16
8
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
0
0
0
24
16
8
0
Reset State:
31
23
15
7
0
0
0
0
HT [31:0], Hash Table [31:0]. These bits represent the lower 32 bits of the 64-bit hash table that are used for hash
table filtering. The multicast hash-filtering mode is detailed later in the data sheet.
55 of 97
DS80C400 Network Microcontroller
CSR Register:
Register Address:
MII Address
14h
Bit Names:
31
23
15
7
—
—
—
—
PHYR [1:0]
—
—
PHYA [4:0]
—
—
—
—
—
—
—
—
—
PHYR [4:2]
—
—
—
—
—
W/ R
BUSY
24
16
8
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
24
16
8
0
Reset State:
0
0
0
0
31
23
15
7
0
0
0
0
PHYA[4:0], PHY Address [4:0]. This 5-bit address specifies the PHY address for 2-wire MII serial-management
bus communication.
PHYR[4:0], PHY Register Select [4:0]. This 5-bit field specifies the PHY register to be accessed in 2-wire MII
serial-management bus communication.
W/R, Write/Read. This bit is used to indicate whether a write or read operation is to be requested of the addressed
PHY/PHY register.
0 = read
1 = write
BUSY, Busy. This status bit indicates when PHY communication is currently taking place on the MII serialmanagement bus. The application must wait until BUSY = 0 before modifying the MII address and MII data
registers prior to each read/write operation.
0 = MII serial-management bus idle
1 = MII serial-management bus busy (write/read in progress)
CSR Register:
Register Address:
MII Data
18h
Bit Names:
31
23
15
7
—
—
—
—
—
—
—
—
—
—
PHYD [15:8]
PHYD [7:0]
—
—
—
—
—
—
24
16
8
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
24
16
8
0
Reset State:
31
23
15
7
0
0
0
0
0
0
0
0
PHYD[15:0], PHY Data [15:0]. These 16 bits contain the data read from the PHY register following a read
operation, or the data to be written to the PHY register prior to a write operation.
56 of 97
DS80C400 Network Microcontroller
CSR Register:
Register Address:
Flow Control
1Ch
Bit Names:
31
23
15
7
—
—
—
—
—
—
PAUSE [15:8]
PAUSE [7:0]
—
—
—
—
0
0
0
0
0
0
0
0
0
0
0
0
—
PCF
—
FCE
—
BUSY
24
16
8
0
0
0
0
0
0
0
0
0
0
0
0
0
24
16
8
0
Reset State:
31
23
15
7
0
0
0
0
0
0
0
0
PAUSE[15:0], Pause Time [15:0]. These bits are only valid in full-duplex mode. These 16 bits contain the value
that is passed in the pause time field when a pause-control frame is generated. The format for the pause-control
frame is shown in Figure 3.
PCF, Pass Pause-Control Frame. This bit is valid for full-duplex mode only. This bit instructs the MAC whether or
not to set the packet filter bit for pause-control frames.
0 = MAC decodes (if FCE = 1) but does not set the receive status word packet-filter bit (default)
1 = MAC decodes (if FCE = 1) and sets the packet-filter bit = 1 for pause-control frames
FCE, Flow Control Enable
0 = MAC flow control is disabled (default)
1 = MAC flow control enabled; pause-control frame for full-duplex, back-pressure for half-duplex
BUSY, Flow Control Busy. The BUSY bit is only valid in full-duplex mode. The BUSY bit should read logic 0
before initiating a pause-control frame. The BUSY bit should be set to logic 1 to initiate a pause-control frame.
Upon successful transmission of a pause-control frame, the BUSY bit returns to logic 0.
0 = no pause-control frame currently being transmitted (default)
1 = initiate a pause-control frame
Figure 3. Pause-Control Frame
ETHERNET FRAME
PREAMBLE
SFD
01 80 C2 00 00 01
(7)
(1)
(6)
SOURCE ADDRESS
(6)
88 08
(2)
57 of 97
00 01
PAUSE TIME (2)
(46)
PAD (42)
CRC-32
(4)
DS80C400 Network Microcontroller
VLAN1 Tag
20h
CSR Register:
Register Address:
Bit Names:
—
—
31
23
15
7
—
—
—
—
—
—
—
—
VLAN1 [15:8]
VLAN1 [7:0]
—
—
—
—
—
—
24
16
8
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
24
16
8
0
Reset State:
0
0
1
1
31
23
15
7
0
0
1
1
VLAN1 [15:0], VLAN1 Tag Identifier [15:0]. These 16 bits contain the VLAN1 tag that is compared against the
13th and 14th bytes of the incoming frame to determine whether it is a VLAN1 frame. If a non-zero match occurs,
the max frame length is extended from 1518 Bytes to 1522 Bytes.
VLAN2 Tag
24h
CSR Register:
Register Address:
Bit Names:
—
—
31
23
15
7
—
—
—
—
—
—
—
—
VLAN2 [15:8]
VLAN2 [7:0]
—
—
—
—
—
—
24
16
8
0
Reset State:
31
23
15
7
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
24
16
8
0
VLAN2 [15:0], VLAN2 Tag Identifier [15:0]. These 16 bits contain the VLAN2 tag that is compared against the
13th and 14th bytes of the incoming frame to determine whether it is a VLAN2 frame. If a non-zero match occurs,
the max frame length is extended from 1518 Bytes to 1538 Bytes.
58 of 97
DS80C400 Network Microcontroller
CSR Register:
Register Address:
Wake-Up Frame Filter
28h
Bit Names:
31
23
15
7
WUFD [31:24]
WUFD [23:16]
WUFD [15:8]
WUFD [7:0]
24
16
8
0
Reset State:
31
23
15
7
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
0
0
0
0
0
0
24
16
8
0
WUFD [31:0], Wake-Up Frame Filter Data [31:0]. These 32 bits are used to access the four available network
wake-up frame filters. Eight accesses to the wake-up frame filter register are needed to read or write all four wakeup frame filters.
CSR Register:
Register Address:
Wake-Up Events Control and Status
2Ch
Bit Names:
31
23
15
7
—
—
—
—
—
—
—
WUFF
—
—
—
MPF
—
—
—
—
—
—
—
—
—
—
—
WUFE
—
—
GU
MPE
—
—
—
—
24
16
8
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
0
0
0
24
16
8
0
Reset State:
31
23
15
7
0
0
0
0
*Power-on reset only. Unaffected by other reset sources.
GU, Global Unicast
0 = frames must pass the destination address filter as well as the wake-up frame filter criteria in order to generate a
wake-up event (default)
1 = frames must pass only the wake-up frame filter criteria to generate a wake-up event
WUFF, Wake-Up Frame Received Flag. This bit is set to logic 1 to indicate when a wake-up event was generated
due to the reception of a network wake-up frame. Application software must clear this flag by writing a 1 to this bit.
MPF, Magic Packet Received Flag. This bit is set to logic 1 to indicate when a wake-up event was generated due
to the reception of a Magic Packet. Application software must clear this flag by writing a 1 to this bit.
WUFE, Wake-Up Frame Enable. Setting this bit to logic 1 invokes sleep mode and allows the reception of network
wake-up frame to generate a wake-up event.
MPE, Magic Packet Enable. Setting this bit to logic 1 invokes sleep mode and allows the reception of a Magic
Packet to generate a wake-up event.
59 of 97
DS80C400 Network Microcontroller
Media Independent Interface (MII)
The DS80C400 contains an IEEE 802.3 MII-compliant PHY interface. This interface contains two basic blocks. The
MII I/O block provides independent transmit and receive data-path I/O and PHY network-status signal inputs. The
MII management block implements a 2-wire serial communication bus to facilitate PHY register access. The block
diagram in Figure 4 shows the signals associated with the DS80C400 MII.
Figure 4. MII Block Diagram
TXCLK
TX_EN
TXD[3:0]
MII I/O BLOCK
RXCLK
(TRANSMIT,
RECEIVE, AND FLOW
CONTROL)
RX_DV
RX_ER
EXTERNAL
PHY
DEVICE
RXD[3:0]
CRS
DS80C400
COL
MII
MANAGEMENT
BLOCK
MDC
MDIO
(SERIAL INTERFACE
BUS TO PHY)
NOTE: WHEN CONNECTING THE DS80C400 TO AN EXTERNAL PHY, DO NOT CONNECT THE RSTOL TO THE RESET OF THE PHY. DOING SO
MAY DISABLE THE ETHERNET TRANSMIT.
MII Management Block
The MII management block allows the host to write control data to and read status from any of 32 registers in any
of 32 PHY controllers. The MII management block communicates with external PHY(s) over a 2-wire serial
interface composed of the MDC serial-clock output pin and the MDIO pin that serves as the I/O line for all address
and data transactions. Data (MDIO) is valid on the rising edge of clock (MDC). The MII address (14h) and MII data
(18h) CSR registers, outlined previously in the CSR Register section, are used by the CPU to monitor and control
the 2-wire MII serial bus. A write to the CSR register MII address triggers the read or write operation. Figure 5
shows the MII management frame format.
Figure 5. MII Management Frame Format
PREAMBLE
(32 bits)
START
(2 bits)
OP CODE
(2 bits)
PHY ADDRESS
(5 bits)
PHY
REGISTER
(5 bits)
TURN
AROUND
(2 bits)
DATA
(16 bits)
IDLE
(1 bit)
READ
111…111
01
10
PHYA [4:0]
PHYR[4:0]
ZZ*
ZZ….ZZ*
Z
WRITE
111…111
01
01
PHYA [4:0]
PHYR[4:0]
10
PHYD[15:0]
Z
*During a read operation, the external PHY drives the MDIO line low for the second bit of the turnaround field to indicate proper synchronization,
and then drives the 16-bits of read data requested.
60 of 97
DS80C400 Network Microcontroller
MII I/O Block
The MII I/O block supports all of the transmit and receive data transactions between the DS80C400 MAC and the
external PHY device as well as monitoring network status signals provided by the PHY.
The transmit interface is composed of TXCLK, TX_EN, and TXD[3:0]. The TXCLK input is the transmit clock
provided by the PHY. For 10Mbps operation, the transmit clock (TXCLK) should be run at 2.5MHz. For 100Mbps,
TXCLK should be run at 25MHz. The TXD[3:0] outputs provide the 4-bit (nibble) data bus for transmitting frame
data to the external PHY. Each transmission begins when the TX_EN output is driven active high, indicating to the
PHY that valid data is present on the TXD[3:0] bus.
The receive interface is composed of RXCLK, RX_DV, RX_ER, and RXD[3:0]. The RXCLK input is the receive
clock provided by the external PHY. This clock (RXCLK) should be run at 2.5MHz for 10Mbps operation and at
25MHz for 100Mbps operation. The RXD[3:0] inputs serve as the 4-bit (nibble) data bus for receiving frame data
from the external PHY. The reception begins when the external PHY drives the RX_DV input high, signaling that
valid data is present on the RXD[3:0] bus. During reception of a frame (RX_DV = 1), the RX_ER input indicates
whether the external PHY has detected an error in the current frame. The RX_ER input is ignored when not
receiving a frame (RX_DV = 0).
The MII also monitors two network status signals that are provided by the external PHY. The CRS (carrier sense)
input is used to assess when the physical media is idle. The COL (collision detect) input is required for half-duplex
operation to signal when a collision has occurred on the physical media.
Ethernet Frames
The basic purpose of the MII I/O block is to deliver and receive Ethernet frames to and from an external PHY,
which controls the physical carrier. The format of the IEEE 802.3 Ethernet frame is shown in Figure 6.
The preamble (7 Bytes) and start-of-frame delimiter (1 Byte) precede the Ethernet frame as a means of
synchronizing to the start of the frame. The first two fields of the Ethernet frame are the destination address and the
source address, each made up of 6 octets (bytes). The destination address field is the field examined by the
address check block to determine whether the applied address filter criteria is met or not. The two bytes following
the source address contain the Length or Type of frame. For Ethernet II (DIX) frames, these two bytes contain the
Type field and the protocol for that specific frame type is embedded in the Data field. For frames where Length is
specified in these two bytes, a header would typically follow in the Data field to convey type/protocol information for
the frame (i.e., 802.2 or SNAP). Since the maximum Data field length for an Ethernet frame is 1500 Bytes, and all
assigned frame types are greater than this value (1500d = 05DCh), one can easily distinguish whether the field
holds Type or Length, allowing both kinds of frames to co-exist on the network. A special case occurs when the
VLAN tag protocol ID (= 8100h) is encountered where the Length or Type is normally expected. The frame is then
considered to be VLAN tagged. The VLAN frame format is described later.
Figure 6. IEEE 802.3 Ethernet Frame
ETHERNET FRAME
PREAMBLE
SFD
DESTINATION ADDRESS
SOURCE ADDRESS
TYPE/LENGTH
DATA
(7)
(1)
(6)
(6)
(2)
(46-1500)
61 of 97
CRC-32
(4)
DS80C400 Network Microcontroller
Address Check Block
The address check block of the Ethernet controller monitors the destination address of all incoming packets and
determines whether the address passes or fails the filter criteria configured by CPU. The outcome of this address
filter test, along with bits signaling whether the frame is a broadcast or multicast frame, is reported by the BCU in a
packet’s receive status word.
All incoming frames can be classified as one of three types: unicast, multicast, or broadcast (a special type of
multicast). A unicast frame contains a 0 in the first received bit of the destination address and is intended for a
single node on the network. A multicast frame contains a 1 in the first received bit of the destination address and is
intended for multiple devices on the network. A broadcast frame is a multicast frame containing all 1’s in the
destination address field and is intended for all network devices. Unless specifically disabled through the disable
broadcast frame (DBF) bit in the CSR MAC control register (00h), broadcast frames are always received by the
DS80C400 MAC.
The address filter criteria is established using five bits found in the CSR MAC control register (00h). Three basic
filter possibilities exist: perfect, inverse, and hash. Perfect filtering requires that the destination address perfectly
match the MAC physical address that has been assigned in CSR registers MAC address high (04h) and MAC
address low (08h). Inverse filtering requires that the destination address be anything other than the assigned MAC
physical address. Perfect and inverse filtering are only applied to unicast frames. Hash filtering uses a user-defined
hash table contained in CSR registers multicast address high (0Ch) and multicast address low (10h) to detect a
successful address match. Figure 7 shows the five bits controlling the destination address filter. Table 15 gives the
valid bit combinations and resultant filter modes. Note that some of the address filter mode control bits can instruct
the address check block to automatically pass or fail certain types of frames.
Figure 7. Address Filter Mode Control Bits
CSR Register MAC Control (00h)
31
0
HP (MAC Control.13) Hash/Perfect Filtering Mode
HO (MAC Control.15) Hash-Only Filtering Mode
IF (MAC Control.17) Inverse Filtering
PR (MAC Control.18) Promiscuous Mode
PM (MAC Control.19) Pass All Multicast
Table 15. Address Filter Modes
PM
0
0
0
1
0
1
x
FILTER MODE CONTROL BITS
PR
IF
HO
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
x
HP
0
0
1
x
1
1
x
DESTINATION ADDRESS FILTER CRITERIA
UNICAST
MULTICAST
PERFECT
FAIL
INVERSE
FAIL
PERFECT
HASH
PERFECT
PASS
HASH
HASH
HASH
PASS
PASS (reset default state = 01000b)
62 of 97
DS80C400 Network Microcontroller
Multicast Hash Filter
Hash filtering of destination addresses requires that a hash table be established. The hash table must be
programmed into the CSR multicast address low and multicast address high registers. When hash filtering has
been selected, the 6 bytes of the destination address are passed through the internal CRC-32 logic. The most
significant 6 bits of the resultant CRC-32 are used to index into the hash table. From those 6 bits, the most
significant bit determines whether multicast address high or low is used, while the lower 5 bits provide the bit index
into the selected CSR register. If the multicast address high or low register bit indexed by the upper 6 bits of the
CRC-32 is programmed to 1, then the destination address passes. Figure 8 shows the hash filtering process.
Figure 8. Hash Table Index Generation
ETHERNET FRAME
PREAMBLE SFD
DESTINATION ADDRESS
SOURCE ADDRESS
TYPE/LENGTH
DATA
CRC-32
CRC-32 OF DESTINATION ADDRESS BYTES
CRC-32 GENERATOR
POLYNOMIAL
. . .
. . .
BIT INDEX
00000b: bit 0
00001b: bit 1
.
.
11110b: bit 30
11111b: bit 31
MULTICAST REGISTER SELECT
0: Multicast Address Low
1: Multicast Address High
VLAN Support
The DS80C400 offers VLAN support through recognition of frames that are tagged as such. Each VLAN tag
provides tag control information (TCI) containing a tag protocol ID (TPID) and VLAN ID. The incoming TPID occupy
the 13th and 14th byte positions, those that would normally contain either the length or type field for the frame. The
TPID is compared against the VLAN1 (20h) and VLAN2 (24h) CSR registers.
If a non-zero match occurs between the TPID and VLAN1 register setting, the frame is recognized as having a
VLAN1 tag. For VLAN1 tagged frames, the TPID is followed by 2 Bytes containing the VLAN ID; therefore, the
MAC extends the maximum legal frame length by a total of 4 Bytes (TPID = 2 Bytes, VLAN ID = 2 Bytes).
If a non-zero match occurs between the TPID and VLAN2 register setting, the frame is recognized as having a
VLAN2 tag. For VLAN2 tagged frames, the TPID is followed by 18 Bytes containing the VLAN ID; therefore, the
MAC extends the maximum legal frame length by a total of 20 Bytes (TPID = 2 Bytes, VLAN ID = 18 Bytes).
Figure 9. VLAN Tagged Frame
ETHERNET FRAME
PREAMBLE SFD DESTINATION ADDRESS
(7)
(1)
(6)
SOURCE ADDRESS TYPE/LENGTH
(6)
(2)
TCI
TPID
VLAN ID
(2)
(2: VLAN1)
(18: VLAN2)
63 of 97
DATA
(46-1500)
CRC-32
(4)
DS80C400 Network Microcontroller
Transmit/Receive Packet Buffer Memory (8kB)
The DS80C400 Ethernet controller uses 8kB of internal SRAM as transmit/receive packet buffer memory. This
SRAM is read/write accessible as data memory by the CPU using the MOVX instruction. The BCU also has access
to this SRAM, and automatically writes/reads packet buffer memory whenever it needs to store or retrieve Ethernet
packet information. The logical MOVX address range of the 8kB SRAM is determined by the IDM1:0 bits of the
MCON (C6h) SFR. Table 16 shows the available address range settings.
When used for Ethernet packet buffer memory, the 8kB SRAM is logically configured into (32) pages of 64 words
each, where a word consists of 4 Bytes. These 32 pages can be dynamically allocated between Ethernet transmit
and receive buffer memory. The five least significant bits of the Ethernet buffer size (EBS; E5h) SFR specify how
many pages are allocated for receive buffer memory. The remaining pages of the 32 are used as transmit buffer
memory. Note that transmit and receive data packets can span multiple pages. The reset default state of the
Ethernet buffer size select bits (EBS.4–EBS.0) is 00000b, which configures all 32 pages as transmit buffer
memory. As an example, setting EBS.4–EBS.0 = 10000b would result in pages 0–15 (16 pages) being configured
as receive buffer memory and pages 16–31 (16 pages) being configured as transmit buffer memory. A setting of
11111b leaves a single page (page 31) for transmit buffer memory and configures pages 0–30 (31 pages) as
receive buffer memory. Changing the transmit/receive buffer-size settings flush the contents of the receive buffer
and the receive FIFO. Figure 10 is an illustration of the 8kB buffer memory map and addressing scheme.
Table 16. Packet Buffer Memory Location
IDM1:0
(MCON.7, MCON.6)
00
01
10
11
INTERNAL 8kB SRAM LOCATION
(ETHERNET PACKET BUFFER MEMORY)
00E000h–00FFFFh
000000h–001FFFh
FFE000h–FFFFFFh
Reserved
Figure 10. Transmit/Receive Data Buffer Memory
8kB INTERNAL SRAM
PAGE 1
PAGE 0
STATUS WORD (WORD 0)
WORD 1
WORD 2
PAGE 1
RECEIVE
BUFFER
(n PAGES)
.
.
.
.
.
.
.
.
.
.
WORD 63
PAGE (n - 2)
BUFFER SIZE
SETTING
(EBS.4–EBS.0)
TRANSMIT
BUFFER
(32 - n PAGES)
PAGE (n - 1)
BUFFER MEMORY ADDRESS (24-Bit)
PAGE n
(Per IDM1:0)
.
.
.
PAGE
WORD
BYTE
EXAMPLE: PAGE 1, WORD 2, BYTE 3
xxxxxxxx xxx
PAGE 31
64 of 97
00001
000010
11
DS80C400 Network Microcontroller
Transmit/Receive Status Words
For each attempt made by the MAC to receive or transmit packet data, the BCU writes a 32-bit transmit or receive
status word back to the first word of the starting page for the packet. This word provides status information needed
by the CPU to determine when and what action should be taken.
Transmit Status Word
Bit Names:
31
RETRY
23
—
15
—
7
NODAT
—
—
HBF
XCOL
—
—
LTCOL
—
—
—
—
COL_CNT [3:0]
XDFR
LSCRS
—
—
NOCRS
—
—
OLTCOL
JABTO
—
—
DFR
ABORT
24
16
8
0
RETRY, Packet Retry. This bit indicates that the current transmit packet has to be retried because of a collision on
the bus. The application has to restart the transmission of the frame when this bit is set to 1. When this bit is reset,
it indicates that the transmission of the current frame is completed. The success or failure to transmit a frame is
indicated by the framed aborted (ABORT) bit.
HBF, Heart-Beat Fail. This bit is only meaningful for ENDEC mode. This bit is not valid if the NODAT or XFDR bit
is set.
0 = heart-beat collision check successful
1 = heart-beat collision check failed
COL_CNT [3:0], Collision Count. These four bits indicate the number of collisions that occurred before the frame
was transmitted. Collision count is valid only in half-duplex mode and it is not valid when the excessive collisions
(XCOL) bit is set.
OLTCOL, Late Collision Observed. This bit is only valid in half-duplex mode and is always set if the late collision
abort (LTCOL) bit is set in the status word.
0 = no late collisions observed
1 = late collision (collision after the first time slot) observed.
DFR, Deferred. This bit is only valid in half-duplex mode.
0 = no deferral required for the frame transmission attempt
1 = MAC had to defer while waiting to transmit because the carrier was not idle
NODAT, Underrun
0 = transmit frame was not aborted due to data underrun
1 = transmit frame aborted because the MAC did not have sufficient data to complete the current frame
transmission
XCOL, Excessive Collisions. This bit is only valid in half-duplex mode.
0 = transmit frame was not aborted due to excessive collisions
1 = transmit frame aborted because of excessive collisions (16 transmit attempts unless DRTY = 1)
LTCOL, Late Collision. This bit is only valid in half-duplex mode.
0 = transmit frame was not aborted due to a late collision
1 = transmit frame aborted due to collision occurring after the collision window of 64 Bytes. This bit is not valid if the
NODAT bit is set.
XDFR, Excessive Deferral. This bit is only valid in half-duplex mode when the MAC control register bit DFR is set.
0 = transmit frame was not aborted due to excessive deferral
1 = transmit frame aborted due to deferral of over 24,288 bit times
LSCRS, Loss of Carrier. This bit is only valid in half-duplex mode.
0 = transmit frame was not aborted due to loss of carrier
1 = transmit frame aborted due to loss of carrier (CRS = 0 during the frame transmission)
65 of 97
DS80C400 Network Microcontroller
NOCRS, No Carrier. This bit is only valid in half-duplex mode.
0 = transmit frame was not aborted due to lack of carrier
1 = transmit frame aborted due to lack of carrier (CRS = 0 when transmit frame initiated)
JABTO, Jabber Timeout
0 = transmit frame was not aborted due to jabber timeout
1 = transmit frame aborted due to jabber timeout (MAC transmitter has been active for twice the Ethernet max
frame length)
ABORT, Frame Aborted
0 = transmit frame was not aborted
1 = transmit frame was aborted by the MAC due to one of the following conditions: jabber timeout, no carrier, loss
of carrier, excessive deferral, late collision, retry count exceeds the attempt limit, and data underrun
Receive Status Word
Bit Names:
31
23
15
7
MF
VLAN2
RUNT
PF
VLAN1
WDOG
FF
CRC
BCF
DRIB
MCF
UCTRL
MII_ER
TYPE
FLEN [13:8]
FLEN [7:0]
CTRL
COL
LEN
LONG
24
16
8
0
MF, Missed Frame
0 = receive frame was not missed
1 = receive frame missed
PF, Packet Filter
0 = current frame failed the packet filter
1 = current frame passed the packet filter
FF, Filter Fail
0 = destination address of the current receive frame passed the applied address filter
1 = destination address of the current receive frame failed the applied address filter
BCF, Broadcast Frame
0 = receive frame is not a broadcast frame
1 = receive frame is a broadcast frame (i.e., destination address is all ones)
MCF, Multicast Frame
0 = receive frame is not a multicast frame
1 = receive frame is a multicast frame (i.e., first bit of the destination address is a 1)
UCTRL, Unsupported Control Frame. This bit is only valid in full-duplex mode.
0 = receive frame is not an unsupported control frame
1 = receive frame is a control frame that is not supported (i.e., one that contains an op code field that is not
supported or one that is not equal to the 64-Byte minimum frame size)
CTRL, Control Frame. This bit is only valid in full-duplex mode.
0 = receive frame is not a control frame
1 = receive frame is a control frame
LEN, Length Error. The frame length check is performed only when type/length field contains frame length (TYPE
= 0). When the data field contains more bytes than specified in the length field, these bytes are assumed to be pad
bytes.
0 = receive frame passed the frame length check
1 = receive frame contained fewer bytes than specified in the length field
66 of 97
DS80C400 Network Microcontroller
VLAN2, Two_Level VLAN Frame
0 = receive frame did not contain a VLAN tag that matched the VLAN2 register
1 = receive frame 13th and 14th bytes matched the two-level VLAN tag register (VLAN2)
VLAN1, One_Level VLAN Frame
0 = receive frame did not contain a VLAN tag that matched the VLAN1 register
1 = receive frame 13th and 14th bytes matched the one-level VLAN tag register (VLAN1)
CRC, CRC Error. This bit is also set to 1 if the RX_ER pin is asserted by the PHY during a reception, even if the
CRC-32 for the frame is correct.
0 = CRC-32 error was not detected for the receive frame
1 = CRC-32 error was detected for the receive frame
DRIB, Dribbling Bit. This bit is not valid if the COL or RUNT bits are set to 1. If DRIB = 1 and CRC = 0, then the
packet is valid.
0 = receive frame did not contain any dribbling bits
1 = receive frame contained dribbling bits (a noninteger multiple of 8 bits)
MII_ER, MII Error
0 = PHY did not assert the RX_ER signal during reception of the frame
1 = PHY asserted the RX_ER signal (indicating an error was detected) during the receive frame
TYPE, Frame Type. This bit is not valid for runt frames less than 14 Bytes.
0 = length specified in the length/type field (i.e., value equal or less than 1500)
1 = type specified in the length/type field (i.e., value greater than 1500)
COL, Collision Seen
0 = receive frame did not incur any collisions
1 = receive frame is damaged by a late collision (one that occurred after the first 64 bytes)
LONG, Frame Too Long. This bit only serves as a status indicator and does not cause frame truncation.
0 = receive frame did not exceed the maximum frame length check
1 = receive frame exceeded the maximum frame length (1518 Bytes, unless VLAN tagged)
RUNT, Runt Frame
0 = receive frame is not a runt frame (<64 Bytes)
1 = receive frame does not meet the minimum required frame size (64 Bytes = 1 time slot) due to a collision or
premature frame termination
WDOG, Watchdog Timeout. The FLEN[13:0] field is not valid when this bit is set.
0 = MAC watchdog timer did not timeout during the receive frame
1 = MAC watchdog timer timed out during the receive frame. The watchdog timer is programmed to twice the
maximum frame length (3036 bit times).
FLEN [13:0], Frame Length [13:0]. This field indicates the receive frame length in bytes, including zero padding
pad (if applicable) and the CRC-32 field, unless automatic pad stripping has been enabled (ASTP = 1). When
ASTP = 1, the frame length includes only the data field.
67 of 97
DS80C400 Network Microcontroller
Ethernet Interrupts
The DS80C400 Ethernet controller supports two interrupt sources: Ethernet power-mode interrupt and the Ethernet
activity interrupt. Each interrupt source has its own enable, priority, and flag bits. The locations of these bits are
documented in the interrupt vector table later in the data sheet (Table 28). Both interrupt sources are globally
enabled or disabled by the EA bit in the IE SFR and both require that the interrupt flags be manually cleared by
application software. The Ethernet power-mode interrupt source, if enabled, can be generated on the reception of a
Magic Packet or network wake-up frame while the Ethernet controller is in sleep mode. The Ethernet activity
interrupt can be triggered when the BCU reports the status of either a transmit or receive packet.
Power Management Block
The DS80C400 Ethernet controller contains a power management block that allows it to be put into a sleep mode
by the CPU, thus conserving power when not actively handling Ethernet traffic.
Sleep mode can be invoked in two different ways. The CPU can issue the ‘Enable Sleep Mode’ command to the
BCU by simply writing the BCUC SFR = 1100b. Alternatively, the Ethernet controller is put into sleep mode when
one or both of the possible wake-up frame sources are enabled. The enable bits for these two wake-up sources,
network wake-up frame and Magic Packet frame, are located in the CSR wake-up frame control and status register
(2Ch). If the network wake-up frame is intended as a wake-up source, the CSR wake-up frame filter register (28h)
should be programmed accordingly prior to invoking sleep mode.
If sleep mode is invoked using the ‘Enable Sleep Mode’ command, the Ethernet controller can be awakened by the
‘Disable Sleep Mode’ command or by either of the two special wake-up frames. If sleep mode is invoked by
enabling one or both wake-up frame sources, only the enabled wake-up frame(s) can remove the condition. To
resume normal Ethernet operation, all enable bits and flag bits (including EPMF of the BCUC SFR) should be
cleared and if the ‘Enable Sleep Mode’ command was used to invoke sleep mode, then the ‘Disable Sleep Mode’
command must be issued.
Magic Packet and Network Wake-Up Frame
The power management block recognizes two types of frames, Magic Packet and network wake-up frame, as
capable of awakening the Ethernet controller from sleep mode. In order for either type of frame to serve as a wakeup source, it must be programmed to do so.
A Magic Packet is an error-free frame that passes the current destination address filter and that, anywhere after the
source address, contains a data sequence of FFFF_FFFF_FFFFh immediately followed by 16 iterations of the
MAC physical address. When a Magic Packet is detected by the power management block, the Magic Packetreceived bit (bit 5 of CSR wake-up events control and status register) is set, and an interrupt request to the CPU is
generated if enabled (EPMI = 1).
A network wake-up frame is one that passes any of the four user-defined frame filters that have been programmed
into the CSR wake-up frame filter register (28h) and passes the destination address filter (if GU = 0). Each filter is
composed of a command, an offset, a byte mask, and a CRC. The command nibble contains a bit (MSB of
command) to select whether unicast (= 0) or multicast (= 1) frames are to be checked and a bit (LSB of command)
used to disable (= 0) or enable (= 1) that individual frame filter. The offset defines the location of the first byte to be
checked in each potential wake-up frame. Since the destination address is checked by the address check block,
the offset should always be greater than 12. The byte mask is used to define which of the 31 bytes, beginning at
the offset, are to be used for the CRC calculation. Bit 31 of the byte mask is always 0, but for each bit j of the byte
mask that is set to a logic 1, byte (offset + j) is included in the CRC-16 calculation. The CRC contains the CRC-16
of the pattern bytes needed to cause a wake-up event. When a network wake-up frame is recognized, the wake-up
frame received bit (bit 6 of CSR wake-up events control and status register) becomes set and an interrupt request
to the CPU is generated if enabled (EPMI = 1). The wake-up frame-filter register structure is shown in Figure 11.
68 of 97
DS80C400 Network Microcontroller
Figure 11. Wake-Up Frame-Filter Structure
31
0
FILTER 0 BYTE MASK
FILTER 1 BYTE MASK
FILTER 2 BYTE MASK
FILTER 3 BYTE MASK
FILTER 3
FILTER 2
FILTER 1
FILTER 0
RESERVED
RESERVED
RESERVED
RESERVED
COMMAND
COMMAND
COMMAND
COMMAND
FILTER 3 OFFSET
FILTER 2 OFFSET
FILTER 1 OFFSET
FILTER 0 OFFSET
FILTER 1 CRC-16
FILTER 0 CRC-16
FILTER 3 CRC-16
FILTER 2 CRC-16
Embedded TINI ROM Firmware
The DS80C400 incorporates an embedded ROM specifically designed for hosting the TINI® runtime environment
and the TINI C libraries. The ROM firmware implements three major components: a full TCP/IPv4/6 stack with
industry-standard Berkeley socket interface, a preemptive task scheduler, and NetBoot functionality. The NetBoot
component uses the TCP/IP stack, socket layer, and task scheduler to provide automatic network boot capability.
NetBoot allows an application to be downloaded from the network and executed by the microcontroller.
To use the ROM firmware, the system is required to have the following hardware components:
 64kB SRAM external memory, mapped (Note 1) at address locations 000000h–00FFFFh
 Memory (SRAM or flash) to store user-application code
 DS2502(-E48) 1-Wire chip (to hold physical MAC address) (Note 2)
 External crystal or oscillator (Note 3)
Note 1: Merged program/data memory configuration is required.
Note 2: Java applications and NetBoot require a DS2502(-E48). Applications written in C can program the MAC address.
Note 3: NetBoot functionality requires the external clock frequency to be at least 7MHz. The clock doubleris not turned on until after NetBoot,
thus 100Mbps NetBoot is not possible unless the external clock source is at least 25MHz. When not in NetBoot, the system clock (external clock
source after internal multiplication or division) must be a minimum of 25MHz for use of the Ethernet 100Mbps mode.
Selecting TINI ROM Code Execution
The DS80C400, following each reset, begins execution of program code at address location 000000h. Since the
DS80C400 contains internal ROM and supports external program code, the user must select which of these two
program memory spaces should be accessed for initial program fetching. There are two mechanisms that control
selection of the internal DS80C400 ROM code. These two controls are the EA pin and the bypass ROM (BROM)
SFR bit. No matter the state of the BROM bit, if the EA pin is held at a logic low level, the ROM code is not entered
and is not accessible to the user code. If the EA pin is at a logic high level, the BROM bit is then examined to
determine whether the internal ROM firmware should be executed or bypassed. If BROM = 0, the ROM code is
executed. Otherwise (BROM = 1), the ROM is bypassed and execution is transferred to external user code at
address 000000h. The BROM bit defaults to 0 on a power-on reset, but is unaffected by other reset sources. This
code selection process can be seen in Figure 12.
DS80C400 ROM Code Execution Flow
Once the internal DS80C400 ROM code has been selected (EA = 1, BROM = 0), it must first execute some basic
configuration code to provide functionality to subsequent ROM operations. Next, the ROM code reads the state of
port pin P1.7. The ROM associates the logic state of P1.7 with the user desire to invoke the serial loader function. If
the serial loader pin (P1.7) is a logic 1, the ROM monitors for activity on serial port 0 and tries to respond to the
external host with its own serial banner. Once serial communication has been established at a supported baud
rate, signified by correct reception of the DS80C400 loader banner and prompt, the user can issue commands. The
serial loader commands are described later in the data sheet. If the serial loader pin is pulled to a logic 0, the ROM
reads the state of port pin P5.3. Much like the association made between P1.7 and invocation of the serial loader,
the ROM links the logic state of P5.3 with the user desire to begin the NetBoot process. If the NetBoot pin (P5.3) is
asserted (logic 0), the ROM initiates the NetBoot process. If the NetBoot pin is not asserted (logic 1), the ROM
executes the find-user-code routine to identify executable user code. Figure 12 illustrates the ROM decisions
described above.
TINI is a registered trademark of Maxim Integrated Products, Inc.
69 of 97
DS80C400 Network Microcontroller
Figure 12. ROM Code Boot Sequence
ANY RESET SOURCE
ACTIVE EXCEPT
RST PIN
RESET SOURCE
ACTIVE?
RST PIN = 1
Y
N
0
N
0
EA PIN?
EA PIN?
1
1
Y
RST PIN = 1?
1
1
BROM BIT?
BROM BIT?
0
0
0
SERIAL
LOADER (P1.7)
PIN?
1
SERIAL LOADER
N
E
N
0
NETBOOT
(P5.3) PIN?
Y
AUTO-BAUD
SUCCESS?
0
NETBOOT
1
SEARCH FOR USER CODE
USER CODE
FOUND?
NO
NETBOOT
(P5.3) PIN?
1
YES
PC = 000000h
PC = LOCATION OF FIRST
TINI TAG FOUND
ENTER STOP MODE AND
HALT OPERATION
RUN USER CODE
70 of 97
0
GENERATE
WATCHDOG RESET
DS80C400 Network Microcontroller
DS80C400 ROM Initialization Code
The 80C400 firmware automatically executes Initialization Code (ROM_Init) to generate the memory map as shown
in Figure 13 and configure the DS80C400 hardware as follows:
Enables 24-bit contiguous address mode
Logically relocates ROM to addresses FF0000h–FF7FFFh
Enables CE0–3, 2MB/chip enable
Enables PCE0–3
Enables CE4–7, 1M/peripheral chip enable
Merged program/data CE0–3, relocate internal XRAM
Enables extended 1kB stack option
Configure to maximum MOVX stretch value
Configure UARTs for Mode 1 serial operation
(ACON.1:0 = 11b)
(ACON.5 =1)
(P4CNT = 2Fh)
(P5CNT = 07h)
(P6CNT = 27h)
(MCON = AFh)
(ACON.2 = 1)
(CKCON.2:0 = 111b)
Figure 13. Memory Map Following Execution of ROM_Init
EXTERNAL MEMORY
merged program/data space
INTERNAL MEMORY
program
data
ROM
CAN/BCU XRAM
FFFFFFh FFDB00h
DATA INACCESSIBLE
PROGRAM
INACCESSIBLE
FF0000h
CE7
E00000h -
CE6
C00000h A00000h -
CE5
CE4
800000h -
CE3
600000h -
CE2
400000h -
CE1
200000h 00FFFFh
CE0
64kB SRAM REQUIRED
000000h -
71 of 97
DS80C400 Network Microcontroller
Serial Loader
The serial loader function implemented by the firmware can be invoked by leaving the serial loader pin (P1.7) at
logic 1 during the boot sequence. When this condition is found, the ROM monitors the RXD0 pin for reception of
the <CR> character (0Dh) at a supported baud rate. The serial loader function uses hardware serial port 0 in mode
1 (asynchronous, one start bit, eight data bits, no parity, and one stop bit in full duplex). The serial loader can
automatically detect certain baud rates and configure itself to that speed. The equation below is used to calculate
the nearest integer-reload value for Timer 2 (used for serial port 0 baud rate generation) based on the external
clock frequency and desired baud rate. The calculated (nearest integer) RCAP2H, RCAP2L reload value may not
result in an exact baud rate match. The calculated reload value and clock frequency can be used in the equation to
solve for the baud rate configurable by the DS80C400. It is advised that the baud rate mismatch be no greater than
±2.5% to maintain reliable communication. The functionality was designed to work for clock rates from 3.680MHz to
75.000MHz and baud rates from 2400 to 115,200.
RCAP2H, RCAP2L = 65,536 -
Oscillator Clock Frequency
32 x Baud Rate
For example, suppose an 18MHz crystal is being used and a 19,200 baud rate is desired. The above equation
yields a nearest integer reload value of FFE3h. This reload value results in a true baud rate of 19396.6 (+1% error).
Once a supported baud rate has been detected, the DS80C400 transmits an ASCII text banner containing
copyright information and prompt for command entry. At this point, the user can issue any of the supported serial
loader commands. A summary of the supported serial loader commands can be seen in Table 17. A detailed
description of each command and further information pertaining to the serial loader can be found in the High-Speed
Microcontroller User’s Guide: Network Microcontroller Supplement.
Table 17. Serial Loader Command Summary
COMMAND
FUNCTION
B
C
D
E
F
G
H, ?
L
N
V
X
Z
Bank select
CRC-16 of memory range
Dump Intel hex data from selected bank
Exit the loader and try to execute code
Fill selected bank memory with hex data
Go: Start executing code at offset 0 in the current bank
Help: Display ROM version and current bank
Load Intel hex into memory
NetBoot
Verify memory against incoming hex
Execute code at a given offset in the current bank
Zap: Erase/clear the current bank.
NetBoot
The NetBoot process affords the user flexibility to download or update code remotely over the network. This
capability is quite powerful. Not only does it make firmware revisions trivial, but it also makes remote diagnostics
very practical. Also, since NetBoot can automatically reload the latest version of the user application code, the
system designer now has the option to select volatile SRAM for code storage.
For the NetBoot function to work, the DS80C400 ROM firmware must initialize certain hardware components and
create the environment needed to support the process. The NetBoot initialization code implements a primitive
memory manager, kicks off the task scheduler, and initializes the 1-Wire hardware, Ethernet driver, TCP/IP stack,
and socket layer.
Once the NetBoot initialization code has completed, the true network boot process can begin. The DS80C400
Ethernet MAC first must be assigned a physical address. Within the NetBoot process, the physical MAC address
can only be acquired through an external DS2502-E48 1-Wire chip. Hence, this 1-Wire chip, containing the MAC
address, is required for successful NetBoot operation. Figure 14 shows the NetBoot code flow chart.
72 of 97
DS80C400 Network Microcontroller
Figure 14. NetBoot Code Flow Chart
NETBOOT
INITIALIZATION CODE
NetBoot PROCESS
ACQUIRE MAC
ADDRESS FROM DS2502
1-WIRE DEVICE
WITH IP
ADDRESS
Y
GET IP ADDRESS FROM
1-WIRE DEVICE
N
DHCP
TFTP/FLASH WRITE
FIND USER CODE
Next, the DS80C400 ROM searches the 1-Wire bus for an external device (separate from the device containing the
MAC address) that contains an IP address and TFTP server IP address. In order to correctly acquire the IP and
TFTP server addresses from an external 1-Wire device, the data read from the device must conform to a specific
format. This format is shown in Figure 15.
Figure 15. 1-Wire IP and TFTP Server IP Address Format
1Dh
54h,49h,4Eh,49h
Address(4)
Gateway(4)
‘TINI’
IPv4
IPv4
29 (LENGTH)
PrefixLength(1)
IPV4
(BYTE
CONVERTED TO
SUBNET MASK)
TFTP Server Address(16)
IPv4 or IPv6
Checksum(2)
1’S COMPLEMENT
OF CRC-16 (LSB
FIRST)
If the IP and TFTP server addresses cannot be acquired from a 1-Wire device, the NetBoot process uses DHCP to
get this information. The DS80C400 broadcasts its MAC address in a DHCP Discover packet. A DHCP server, if
available, should then respond with an IP address offering. The DS80C400 subsequently requests the IP address,
to which the DHCP server must acknowledge. In the DHCP acknowledge packet, the TFTP server IP address is
then read from the “next server IP” field. Because some DHCP servers do not allow configuration of the “next
server IP” field, the DS80C400 recognizes the site-specific option 150 (also used on Cisco IP phones to get TFTP
server IP addresses). When option 150 is present in the acknowledge packet, it will take precedence over the “next
server IP” field.
73 of 97
DS80C400 Network Microcontroller
Now armed with an IP address and TFTP server IP address, the DS80C400 tries to find code to be loaded into
external program memory. The ROM first requests to read the file from the TFTP server coinciding with its unique
physical MAC address (e.g., 006035AB9811). If the request is denied, it issues a second, less specific, request to
read the filename associated with the DS80C400 ROM revision (e.g. TINI400-1.0.1). If this request is denied, then
lastly it attempts to read from the TFTP server the file ‘TINI400.’ Using this strategy, the TFTP server operator can
distinguish between different devices and/or different releases of the DS80C400 ROM firmware.
After successfully locating the desired file on the TFTP server, the DS80C400 must transfer and program the file
into external memory. Currently, the DS80C400 only offers programming support for SRAM and AMD compatible
flash memory devices. The NetBoot code expects the transferred file to be in the Maxim tbin2 format. The tbin2
format consists of one or more records, allowing binary concatenation of multiple images into one file. Figure 16
illustrates the tbin2 file format.
For each 64kB bank to be programmed, the ROM first performs a CRC-16 of the current memory bank contents. If
the CRC-16 of the current memory matches the data to be programmed, the bank is left alone. If the CRC-16
differs, it performs a couple of write/read-back operations to assess whether the bank is flash or SRAM and then
executes the erasure (if flash) and programming.
After completion of the TFTP server file transfer and programming of external memory, the NetBoot process
concludes by updating a ‘previous TFTP success’ flag and executing the ROM find-user-code routine.
If either DHCP or the TFTP transfer fail, the NetBoot code checks whether the TFTP transfer has been successful
in a previous attempt. (Note that this feature requires cooperation by the user application.) If so, the DS80C400
ROM exits NetBoot and transfers execution to the find-user-code routine. If the TFTP transfer has not been
successful in the past, the DS80C400 ROM allows the watchdog timer to reset the DS80C400.
Figure 16. Maxim tbin2 Record and File Format
tbin2 file
tbin2 record
tbin2 record
tbin2 record
VERSION
TARGET ADDRESS (3)
LENGTH-1 (2)
CRC-16 (2)
tbin2 record
BINARY DATA (LENGTH)
tbin2 record
.
.
.
tbin2 record
FIELD
Version:
Target Address:
Length-1:
CRC-16:
FORMAT (NOTES)
01h (versions other than 01h reserved for future use)
LSB, MSB, XSB (target addresses > FF0000h reserved)
LSB, MSB
LSB, MSB
Find-User Code
The DS80C400 ROM firmware attempts to find valid user code by searching for specific signature bytes at the
beginning of each 64kB block of memory. The search begins at address location C00000h and continues
downward through memory in decrements of 64kB until executable code is located or failure occurs (search
terminates at 000000h). For the find-user-code routine to judge a block of memory as valid executable code, it
must be tagged with the signature bytes shown in Figure 17.
74 of 97
DS80C400 Network Microcontroller
Figure 17. User Code Signature (Required by Find-User Code)
SIGNATURE BYTES
80h,xxh
54h,49h,4Eh,49h
SJMP xx
USER CODE
Segment Address(1)
‘TINI’
Once a valid signature is found, the signature byte at offset 6, referred to in Figure 17 as the segment address, is
examined to determine whether execution control should be transferred immediately or whether the search should
continue. If the segment address byte equals 00h or matches the most significant address byte for the 64kB block
being examined, execution is transferred to the user code. If the segment address byte does not match, that
segment address byte is used to determine the next memory block examined for a valid signature.
Exported ROM Functions
The DS80C400 ROM firmware implements many functions that are made accessible to the user application code.
For user application code to call a specific function, the location of that function must be known. The absolute
address location of each DS80C400 ROM function must be read from an export table (also found in the ROM). To
allow flexibility for future ROM firmware structural changes and improvements, the export table itself is not
connected to a specific address range, but instead a 3-Byte pointer to the start of the export table is fixed at
addresses FF0002h (XSB), FF0003h (MSB), and FF0004h (LSB). The first three bytes of the export table contain
the quantity of function entries in the export table. In 3-Byte increments, following the first three bytes, the rest of
the table contains absolute address locations for the exported ROM functions. Thus, once the export table location
has been discovered, the index for a given function/structure (Table 18) can be used to find its absolute address
(Function address = ExportTable[Index x 3]). Figure 18 illustrates the method for locating the export table and a
specific ROM function. Table 18 shows the contents of the ROM export table. Brief descriptions of the functionality
provided by the TCP/IP stack, socket layer, and task manager are included after the table, while the full details for
these and other exported ROM functions are covered in the High-Speed Microcontroller User’s Guide: Network
Microcontroller Supplement.
Figure 18. Finding the Location of an Exported ROM Function
TINI400 ROM
(LOGICALLY LOCATED FF0000h–
FFFFFFh WHEN MROM = 1)
FF0000h
Export Table
Address
ROM FUNCTION EXPORT TABLE
FFxxxxh
FFxxxxh +03h
ROM Exported Function [3]
Number of Functions Exported (n)
2
Function [index=1] Address
FFxxxxh +06h
Function [2] Address
FFxxxxh +09h
Function [3] Address
1
FFxxxxh
.
.
.
FFxxxxh +(n x 3)h
Function [n] Address
FFFFFFh
75 of 97
ROM Export Table
DS80C400 Network Microcontroller
Table 18. ROM Export Table
INDEX
0
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
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
FUNCTION
Num_Fn,0,0
crc16
mem_clear
mem_copy
mem_compare
add_dptr0
add_dptr1
sub_dptr0
sub_dptr1
getpseudorandom
rom_kernelmalloc
rom_kernelfree
rom_malloc
rom_malloc_dirty
rom_free
rom_deref
rom_getfreeram
socket
closesocket
sendto
recvfrom
connect
bind
listen
accept
recv
send
getsockopt
setsockopt
getsockname
getpeername
cleanup
avail
join
leave
ping
getnetworkparams
setnetworkparams
getipv6params
getethernetstatus
gettftpserver
settftpserver
eth_processinterrupt
arp_generaterequest
MAC_ID
dhcp_init
dhcp_setup
dhcp_startup
dhcp_run
dhcp_status
dhcp_stop
rom_dhcp_notify
tftp_init
tftp_first
tftp_next
TFTP_MSG
task_genesis
task_getcurrent
task_getpriority
task_setpriority
task_fork
DESCRIPTION/GROUP
Number of functions following in the table
Utility functions
Memory manager
Socket functions
Ethernet interrupt handler
Generates ARP request
Pointer to MAC ID
DHCP functions
TFTP functions
Task scheduler functions
76 of 97
DS80C400 Network Microcontroller
INDEX
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
FUNCTION
task_kill
task_suspend
task_sleep
task_signal
rom_task_switch_in
rom_task_switch_out
EnterCritSection
LeaveCritSection
rom_init
rom_copyivt
rom_redirect_init
mm_init
km_init
ow_init
network_init
eth_init
init_sockets
tick_init
WOS_Tick
BLOB
WOS_IOPoll
IP_ProcessReceiveQueues
IP_ProcessOutput
TCP_RetryTop
ETH_ProcessOutput
IGMP_GroupMaintenance
IP6_ProcessReceiveQueues
IP6_ProcessOutput
PARAMBUFFER
RAM_TOP
BOOT_MEMBEGIN
BOOT_MEMEND
OWM_First
OWM_Next
OWM_Reset
OWM_Byte
OWM_Search
OWM_ROMID
Autobaud
tftp_close
DESCRIPTION/GROUP
Enter/Leave critical section
Initialization functions
Timer interrupt handler
Start address of the memory area ignored by NetBoot
Asynchronous TCP/IP maintenance functions
Pointer to parameter buffer
Address of pointer to end of RAM used by NetBoot
1-Wire master functions
Serial port 0 baud rate detection
77 of 97
DS80C400 Network Microcontroller
TCP/IP Stack and Berkeley Sockets
The ROM firmware implements TCP/IP Ethernet networking over an industry-standard/Berkeley socket interface.
The stack supports TCP and UDP transport protocols, allowing a maximum of 24 client/server sockets for either
IPv4 or IPv6. Table 19 lists the socket functions implemented and accessible in the ROM firmware. The full details
of each socket function are contained in the High-Speed Microcontroller User’s Guide: Network Microcontroller
Supplement.
Figure 19 illustrates the typical sequences for using TCP/UDP client/server sockets. The IPv4 implementation
supports multicasting, ICMP echo request (“ping”), DHCP client, and TFTP client. It does not, however, allow IP
packet fragmentation or reassembly, and it ignores the extended IP options field. The IPv6 implementation
supports ICMP and the TFTP client protocols.
Table 19. Socket Functions
FUNCTION
socket
closesocket
sendto
recvfrom
connect
bind
listen
accept
recv
send
getsockopt
setsockopt
getsockname
getpeername
cleanup
avail
join
leave
ping
setnetworkparams
getnetworkparams
getipv6params
getethernetstatus
gettftpserver
settftpserver
DESCRIPTION
Creates the specified TCP or UDP network socket
Closes the specified socket
Sends a UDP datagram to the specified address
Receives a UDP datagram
Connects a TCP socket to the specified address
Binds a socket to the specified address, port
Listens for connections on the specified socket
Accepts a TCP connection on the specified socket
Reads data from the specified TCP socket connection
Sends data to the specified TCP socket connection
Gets options for the specified socket
Sets options for the specified socket
Gets current local address for the specified socket
Gets current remote address for the specified TCP socket
Closes all sockets associated with the specified task ID
Returns the number of bytes available for reading on the specified TCP socket
Adds the specified UDP socket to a specified multicast group
Removes the specified UDP socket from a specified multicast group
Sends ICMP echo request to the specified address
Sets the IPv4 address and configuration parameters
Gets the IPv4 address and configuration parameters
Gets the IPv6 address
Gets the status of the Ethernet link
Gets the IP address of the TFTP server
Sets the IP address of the TFTP server
Figure 19. Typical TCP/UDP Sockets
TCP
Server
TCP
Client
UDP
Unicast
UDP
Multicast
socket
bind, getsockopt, setsockopt (optional)
listen (max. 16)
accept
join
connect
sendto, recvfrom
leave
avail, send, recv
closesocket
78 of 97
DS80C400 Network Microcontroller
Task Scheduler
The DS80C400 ROM firmware implements a priority based preemptive task scheduler. Each task created is
represented in a task ring by a corresponding task control block (TCB). The TCB holds critical information specific
to the task, such as the ID, priority, event bit mask, wake-up time, and pointers to state information and next task.
Using a timer, the scheduler is run approximately every 4ms (at 18.432MHz crystal frequency) unless deferred
because another interrupt is in progress. The scheduler supports an unlimited number of tasks and allows addition,
deletion, or modification on the fly. However, one should realize that increasing the number of tasks increases the
time needed by the scheduler to search and prioritize the ring. The High-Speed Microcontroller User’s Guide:
Network Microcontroller Supplement provides greater detail about the task scheduler and its functionality.
Controller Area Network (CAN) Module
The DS80C400 incorporates one CAN controller that is fully compliant with the CAN 2.0B specification. CAN is a
highly robust, high-performance communication protocol for serial communications. Popular in a wide range of
applications including automotive, medical, heating, ventilation, and industrial control, the CAN architecture allows
for the construction of sophisticated networks with a minimum of external hardware.
The CAN controller supports the use of 11-bit standard or 29-bit extended acceptance identifiers for up to 15
messages, with the standard 8-Byte data field, in each message. Fourteen of the 15 message centers are
programmable in either transmit or receive modes, with the 15th designated as an FIFO-buffered, receive-only
message center to help prevent data overruns. All message centers have two separate 8-bit media masks and
media arbitration fields for incoming message verification. This feature supports the use of higher-level protocols
that use the first and/or second byte of data as a part of the acceptance layer for storing incoming messages. Each
message center can also be programmed independently to test incoming data with or without the use of the global
masks.
Global controls and status registers in the CAN unit allow the microcontroller to evaluate error messages, generate
interrupts, locate and validate new data, establish the CAN bus timing, establish identification mask bits, and verify
the source of individual messages. Each message center is individually equipped with the necessary status and
control bits to establish direction, identification mode (standard or extended), data field size, data status, automatic
remote frame request and acknowledgment, and perform masked or nonmasked identification-acceptance testing.
Communicating with the CAN Module
The microcontroller interface to the CAN modules is divided into two groups of registers. All the global CAN status
and control bits as well as the individual message center control/status registers are located in the SFR map. The
remaining registers associated with the message centers (data identification, identification/arbitration masks, format
and data) are located in MOVX data space. The CMA bit (MCON.5) allows the message centers to be mapped to
either 00DB00h–00DBFFh (CMA = 0) or FFDB00h–FFDBFFh (CMA = 1), reducing the possibility of a memory
conflict with application software. The internal architecture of the DS80C400 requires that the device be in one of
the two 24-bit addressing modes when the CMA bit is set to correctly access the CAN MOVX memory. A special
lockout feature prevents the accidental software corruption of the control, status, and mask registers while a CAN
operation is in progress. Each CAN controller uses a total of 15 message centers. Each message center is
composed of four specific areas that include the following:
1) Four arbitration registers (C0MxAR0-3) that store either the 11-bit or 29-bit arbitration value. These registers
are located in the MOVX memory map.
2) A format register (C0MxF) that informs the CAN controller as to the direction (transmit or receive), the number
of data bytes in the message, the identification format (standard or extended), and the optional use of the
identification mask or media mask during message evaluation. This register is located in the MOVX memory
map.
3) Eight data bytes for storage of 0 to 8 Bytes of data (C0MxD0–7) are located in the MOVX memory map.
4) Message control registers (C0MxC) are located in the SFR memory for fast access.
Each of the message centers is identical with the exception of message center 15. Message center 15 has been
designed as a receive-only center and is also buffered through the use of a two-message FIFO to help prevent
message loss in a message-overrun situation. The receipt of a third message before either of the first two are read
overwrites the second message, leaving the first message undisturbed.
79 of 97
DS80C400 Network Microcontroller
Modification of the CAN registers located in MOVX memory is protected through the SWINT bit. Consult the
description of this bit in the High-Speed Microcontroller User’s Guide: Network Microcontroller Supplement for more
information. The CAN module contains a block of control/status/mask registers, 14 functionally identical message
centers, plus a 15th message center that is receive-only and incorporates a buffered FIFO. Table 20 describes the
organization of the message centers located in MOVX space.
Table 20. CAN Controller MOVX Memory Map
CONTROL/STATUS/MASK REGISTERS
REGISTER
7
6
C0MID0
MID07
MID06
C0MA0
M0AA7
M0AA6
C0MID1
MID17
MID16
C0MA1
M1AA7
M1AA6
C0BT0
SJW1
SJW0
C0BT1
SMP
TSEG26
C0SGM0
ID28
ID27
C0SGM1
ID20
ID19
C0EGM0
ID28
ID27
C0EGM1
ID20
ID19
C0EGM2
ID12
ID11
C0EGM3
ID4
ID3
C0M15M0
ID28
ID27
C0M15M1
ID20
ID19
C0M15M2
ID12
ID11
C0M15M3
ID4
ID3
CAN 0 MESSAGE CENTER 1
C0M1AR0
C0M1AR1
C0M1AR2
C0M1AR3
C0M1F
C0M1D0–7
DTBYC3
5
4
3
2
1
0
MID05
M0AA5
MID15
M1AA5
BPR5
TSEG25
ID26
ID18
ID26
ID18
ID10
ID2
ID26
ID18
ID10
ID2
MID04
M0AA4
MID14
M1AA4
BPR4
TSEG24
ID25
0
ID25
ID17
ID9
ID1
ID25
ID17
ID9
ID1
MID03
M0AA3
MID13
M1AA3
BPR3
TSEG13
ID24
0
ID24
ID16
ID8
ID0
ID24
ID16
ID8
ID0
MID02
M0AA2
MID12
M1AA2
BPR2
TSEG12
ID23
0
ID23
ID15
ID7
0
ID23
ID15
ID7
0
MID01
M0AA1
MID11
M1AA1
BPR1
TSEG11
ID22
0
ID22
ID14
ID6
0
ID22
ID14
ID6
0
MID00
M0AA0
MID10
M1AA0
BPR0
TSEG10
ID21
0
ID21
ID13
ID5
0
ID21
ID13
ID5
0
RESERVED
CAN 0 MESSAGE 1 ARBITRATION REGISTER 0
CAN 0 MESSAGE 1 ARBITRATION REGISTER 1
CAN 0 MESSAGE 1 ARBITRATION REGISTER 2
CAN 0 MESSAGE 1 ARBITRATION REGISTER 3
DTBYC2
DTBYC1
DTBYC0
MEME
T/R
EX/ST
CAN 0 MESSAGE 1 DATA BYTES 0 to 7
RESERVED
WTOE
MDME
MOVX DATA
ADDRESS*
xxDB00h
xxDB01h
xxDB02h
xxDB03h
xxDB04h
xxDB05h
xxDB06h
xxDB07h
xxDB08h
xxDB09h
xxDB0Ah
xxDB0Bh
xxDB0Ch
xxDB0Dh
xxDB0Eh
xxDB0Fh
xxDB10h–11h
xxDB12h
xxDB13h
xxDB14h
xxDB15h
xxDB16h
xxDB17h–1Eh
xxDB1Fh
CAN 0 MESSAGE CENTERS 2 to 14
MESSAGE CENTER 2 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 3 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 4 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 5 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 6 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 7 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 8 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 9 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 10 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 11 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 12 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 13 REGISTERS (similar to Message Center 1)
MESSAGE CENTER 14 REGISTERS (similar to Message Center 1)
xxDB20h–2Fh
xxDB30h–3Fh
xxDB40h–4Fh
xxDB50h–5Fh
xxDB60h–6Fh
xxDB70h–7Fh
xxDB80h–8Fh
xxDB90h–9Fh
xxDBA0h–AFh
xxDBB0h–BFh
xxDBC0h–CFh
xxDBD0h–DFh
xxDBE0h–EFh
CAN 0 MESSAGE CENTER 15
—
C0M15AR0
C0M15AR1
C0M15AR2
C0M15AR3
C0M15F
C0M15D0—
C0M15D7
Reserved
CAN 0 MESSAGE 15 ARBITRATION REGISTER 0
CAN 0 MESSAGE 15 ARBITRATION REGISTER 1
CAN 0 MESSAGE 15 ARBITRATION REGISTER 2
CAN 0 MESSAGE 15 ARBITRATION REGISTER 3
DTBYC3
DTBYC2
DTBYC1
DTBYC0
0
EX/ST
MEME
WTOE
xxDBF0h–F1h
xxDBF2h
xxDBF3h
xxDBF4h
xxDBF5h
MDME
xxDBF6h
CAN 0 MESSAGE 15 DATA BYTE 0 to 7
xxDBF7h–FEh
Reserved
xxDBFFh
*The first byte of the CAN 0 MOVX memory address is dependent on the setting of the CMA bit (MCON.5) CMA = 0, xx = 00; CMA = 1, xx = FF.
80 of 97
DS80C400 Network Microcontroller
CAN Interrupts
The DS80C400 provides one interrupt source for the CAN controller. The CAN interrupt source can be triggered by
a receive/transmit acknowledgment from one of the 15 message centers or an error condition.
Each message center has individual ETI (transmit) and ERI (receive) interrupt enable bits and INTRQ flag bits that
are found in the corresponding message control (C0MxC) SFR. If the ETI or ERI bits have been set for a message
center, the successful transmission or receipt of a message, respectively, sets the INTRQ bit for that message
center. The INTRQ bit can only be cleared through software. All message center interrupt flags (INTRQ) of the
CAN module are ORed together to produce a single interrupt source for the CAN controller. For the microcontroller
to acknowledge any individual message center interrupt request, the global interrupt enable bit (IE.7) and the CAN
0 interrupt enable bit, EIE.6, must both be set.
Interrupt assertion of error and status conditions associated with the CAN module is controlled by the ERIE and
STIE bits located in the CAN 0 control (C0C) SFR. These interrupt sources also require that the global interrupt
enable (EA = IE.7) and the CAN 0 interrupt enable (C0IE = EIE.6) bits be set in order to be acknowledged by the
microcontroller.
Arbitration and Masking
After the CAN module has ascertained that an incoming message is bit error-free, the identification field of that
message is then compared against one or more arbitration values to determine if they are loaded into a message
center. Each enabled message center (see the MSRDY bit in the CAN message control register) is tested in order
from 1 to 15. The first message center to successfully pass the test receives the incoming message and ends the
testing. The use of masking registers allows the use of more complex identification schemes, as tests can be made
based on bit patterns rather than an exact match between all bits in the identification field and arbitration values.
The CAN controller also incorporates a set of five masks to allow messages with different IDs to be grouped and
successfully loaded into a message center; note that some of these masks are optional as per the bits shown in
Table 21.
There are several possible arbitration tests, varying according to which message center is involved. If all of the
enabled tests succeed, the message is loaded into the respective message center. The most basic test, performed
on all messages, compares either 11 (CAN 2.0A) or 29 (CAN 2.0B) bits of the identification field to the appropriate
arbitration register, based on the EX/ST bit in the CAN 0 format register. The MEME bit (C0MxF.1) controls whether
the arbitration and ID registers are compared directly or through a mask register. A special set of arbitration
registers dedicated to message center 15 allows added flexibility in filtering this location.
If desired, further arbitration can be performed by comparing the first two bytes of the data field in each message
against two 8-bit media arbitration register bytes. The MDME bit in the CAN message center format registers
(C0MxF.0) either disables (MDME = 0) arbitration, or enables (MDME = 1) arbitration using the media ID mask
registers 0–1.
If the 11-bit or 29-bit arbitration and the optional media-byte arbitration are successful, the message is loaded into
the respective message center. The format register also allows the microcontroller to program each message
center to function in a receive or transmit mode through the T/R bit and to use from 0 to 8 data bytes within the data
field of a message. Note that message center 15 can only be used in a receive mode. To avoid a priority inversion,
the DS80C400 CAN controller is configured to reload the transmit buffer with the message of the highest priority
(lowest message center number) whenever an arbitration is lost or an error condition occurs.
81 of 97
DS80C400 Network Microcontroller
Table 21. Arbitration/Masking Feature Summary
TEST NAME
ARBITRATION
REGISTERS
MASK REGISTERS
CONTROL BITS
AND CONDITIONS
Standard 11-bit
Arbitration
(CAN 2.0A)
Message Center
Arbitration Registers 0–1
(Located in each message
center, MOVX memory)
Standard Global Mask
Registers 0–1 (Located in
CAN control/status/mask
register bank, MOVX
memory)
EX/ST = 0
MEME = 0: Mask register ignored. ID and
arbitration register must match exactly.
MEME = 1: Only bits corresponding to 1 in
mask register are compared in ID and
arbitration registers.
Extended 29-bit
Arbitration
(CAN 2.0B)
Message Center
Arbitration Registers 0–3
(Located in each message
center, MOVX memory)
Extended Global Mask
Registers 0–3 (Located in
CAN control/status/mask
register bank, MOVX
memory)
EX/ST = 1
MEME = 0: Mask register ignored. ID and
arbitration register must match exactly.
MEME = 1: Only bits corresponding to 1 in
mask register are compared in ID and
arbitration registers.
Media Byte
Arbitration
Media Arbitration Registers
0–3 (Located in CAN
control/status/mask
register bank, MOVX
memory)
Media ID Mask Registers
0–1 (Located in CAN
control/status/mask
register bank, MOVX
memory)
MDME = 0: Media byte arbitration disabled.
MDME = 1: Only bits corresponding to 1 in
Media ID mask register are compared
between data bytes 1 and 2 and Media
arbitration registers.
Message Center 15
Arbitration Registers 0–1
(Located in message
center 15, MOVX memory)
Message Center 15 Mask
Registers 0–1 (Located in
CAN control/status/mask
register bank, MOVX
memory)
EX/ST = 0
MEME = 0: Mask register ignored. ID and
arbitration register must match exactly.
MEME = 1: Message center 15 mask
registers are ANDed with Global Mask
register. Only bits corresponding to 1 in
resulting value are compared in ID and
arbitration registers.
Message Center 15
Arbitration Registers 0–3
(Located in message
center 15, MOVX memory)
Message Center 15 Mask
Registers 0–3 (Located in
CAN control/status/mask
register bank, MOVX
memory)
EX/ST = 1
MEME = 0: Mask register ignored. ID and
arbitration register must match exactly.
MEME = 1: Message center 15 mask
registers are ANDed with Global Mask
register. Only bits corresponding to 1 in
resulting value are compared in ID and
arbitration registers.
Message Center
15, Standard 11bit Arbitration
(CAN 2.0A)
Message Center
15, Extended
29-bit Arbitration
(CAN 2.0B)
Message Buffering/Overwrite
If a message center is configured for reception (T/R = 0) and the previous message has not been read (DTUP = 1),
then the disposition of an incoming message to that message center is controlled by the WTOE bit (located in CAN
arbitration register 3 of each message center). When WTOE = 0, the incoming message is discarded and the
current message untouched.
If the WTOE bit is set, the incoming message is received and written over the existing data bytes in that message
center. The receiver overwrite bit (ROW) also is set in the corresponding message center control register, located
in SFR memory.
Message center 15 is unique in that it incorporates a buffer that can receive up to two messages without loss. If a
message is received by message center 15 while it contains an unread message, the new incoming message is
held in an internal buffer. When the CAN controller reads the message center 15 memory location and then clears
DTUP = INTRQ = EXTRQ = 0, the contents of the internal buffer are automatically loaded into the message center
15 MOVX memory location.
The message center 15 WTOE bit controls what happens if a third message is received when both the message
center 15 MOVX memory location and the buffer contain unread messages. If WTOE = 0, the new message is
discarded, leaving the message center 15 MOVX memory location and the buffer untouched. If WTOE = 1, then
the third message writes over the buffered message but leaves the message center 15 MOVX memory location
untouched.
82 of 97
DS80C400 Network Microcontroller
Error Counter Interrupt Generation
The CAN module can be configured to alert the microcontroller when either 96 or 128 errors have been detected by
the transmit or receive error counters. The error-count select bit, ERCS (C0C.1), selects whether the limit is 96
(ERCS = 0) or 128 (ERCS = 1) errors. When the error limit is exceeded, the CAN error-count exceeded bit CECE
(C0S.6) is set. If the ERIE, C0IE, and EA SFR bits are configured, an interrupt is generated. If the ERCS bit is set,
the device generates an interrupt when the CECE bit is set or cleared, if the interrupt is enabled.
Bit Timing
Bit timing of the CAN transmission can be adjusted per the CAN 2.0B specification. The CAN 0 bus timing register
zero (C0BT0), located in the control/status/mask register block in MOVX memory, controls the PHASE_SEG1 and
PHASE_SEG2 time segments and the baud rate prescaler (BPR5–BPR0). The CAN 0 bus timing register one
(C0BT1) contains the controls for the sampling rate and the number of clock cycles assigned to the Phase
Segment 1 and 2 portions of the nominal bit time. The values of both of the bus timing registers are automatically
loaded into the CAN controller following each software change of the SWINT bit from a 1 to a 0 by the
microcontroller. The bit timing parameters must be set before starting operation of the CAN controller. These
registers are modifiable only during a software initialization, (SWINT = 1), when the CAN controller is not in a busoff mode, and after the removal of a system reset or a CAN reset. To avoid unpredictable behavior of the CAN
controller, the software cannot clear the SWINT bit when TSEG1 and TSEG2 are both cleared to 0.
1-Wire Bus Master
The DS80C400 incorporates a 1-Wire bus master to support communication to external 1-Wire devices. The bus
master provides complete control of the 1-Wire bus and coordinates transmit (Tx)/receive (Rx) activities with
minimal supervision by the CPU. All timing and control sequences for the bus are generated within the bus master.
Communication between the CPU and the bus master is accomplished through read/write access of the 1-Wire
master address (OWMAD; EEh) and 1-Wire master data (OWMDR; EFh) SFRs. When 1-Wire bus activity
generates a condition that requires servicing by the CPU, the bus master sets the appropriate status bit to create
an interrupt request to the CPU. If the 1-Wire bus master interrupt source has been enabled, the CPU services the
request according to the priority that has been assigned. The 1-Wire bus master supports bit banging, search ROM
accelerator, and overdrive modes. Detailed operation of the 1-Wire bus is described in The Book of iButton
Standards (www.maxim-ic.com/iButtonBook).
Communicating with the Bus Master
The microcontroller interface to the 1-Wire bus master is through two SFRs, 1-Wire master address (OWMAD;
EEh), and 1-Wire master data (OWMDR; EFh). These two registers allow read/write access of the six internal
registers of the 1-Wire bus master. The internal registers provide a means for the CPU to configure and control
transmit/receive activity through the bus master.
The three least significant bits (A2:A0) of the OWMAD SFR specify the address of the internal register to be
accessed. The OWMDR SFR is used for read/write access to the implemented bits of the specified internal
register. All internal registers are read/write accessible except the interrupt flag register (xxxxx010b), which allows
only read access to interrupt status flags. It should also be noted that all writes to the Tx/Rx buffer register
(xxxxx001b) are directed to the Tx buffer and all reads retrieve data from the Rx buffer. The 1-Wire bus master
internal register map is shown in Table 22.
Table 22. 1-Wire Bus Master Internal Register Map
REGISTER ADDRESS*/
FUNCTION
000
Command
001
Tx/Rx Buffer
010
Interrupt Flag
011
Interrupt Enable
100
Clock Divisor
101
Control
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
—
D7
OW_LOW
EOWL
CLK_EN
EOWMI
—
D6
OW_SHORT
EOWSH
—
OD
—
D5
RSRF
ERSF
—
BIT_CTL
—
D4
RBF
ERBF
DIV2
STP_SPLY
OW_IN
D3
TEMT
ETMT
DIV1
STPEN
FOW
D2
TBE
ETBE
DIV0
EN_FOW
SRA
D1
PDR
—
PRE1
PPM
1WR
D0
PD
EPD
PRE0
LLM
*Logic states represented by A2:A0 other than those listed in the table are considered to be invalid addresses and are not supported by the bus
master. When OWMAD contains an invalid address, reads of OWMDR return invalid data, and writes to OWMDR do not change the internal
register contents.
83 of 97
DS80C400 Network Microcontroller
Clock Control
All 1-Wire timing patterns are generated using a base clock of 1.0MHz. To create this base clock frequency for the
1-Wire bus master, the microcontroller system clock must be internally divided down. The clock divisor internal
register implements bits to control this clock division and generation. The prescaler bits (PRE1:PRE0) divide the
microcontroller system clock by 1, 3, 5, or 7 for settings of 00b, 01b, 10b, and 11b respectively. The divider bits
(DIV2:DIV0) control the circuitry, which then divides the prescaler output clock by 1, 2, 4, 8, 16, 32, 64, or 128. The
CLK_EN bit (bit 7 of the clock divisor register) enables or disables the clock generation circuitry. Setting CLK_EN to
a logic 1 enables the clock generation circuitry while clearing the bit disables the clock generation circuitry. The
clock divisor register must be configured properly before any 1-Wire communication can take place. Table 23
shows the proper selections for the PRE1:PRE0 and DIV2:DIV0 register bits for a given microcontroller system
clock. Note that the clock generation circuitry requires that the microcontroller system clock be between 3.2MHz
and 75MHz, preferably with 50% duty cycle.
Table 23. Clock Divisor Register Settings
SYSTEM CLOCK
FREQUENCY (MHz)
MIN
MAX
4.0
< 5.0
5.0
< 6.0
6.0
< 7.0
7.0
< 8.0
8.0
< 10.0
10.0
< 12.0
12.0
< 14.0
14.0
< 16.0
16.0
< 20.0
20.0
< 24.0
24.0
< 28.0
28.0
< 32.0
32.0
< 40.0
40.0
< 48.0
48.0
< 56.0
56.0
< 64.0
64.0
75.0
DIVIDER
RATIO
DIV2:DIV0
DIVIDE BITS
SELECTION
PRE1:PRE0
4
5
6
7
8
10
12
14
16
20
24
28
32
40
48
56
64
010
000
001
000
011
001
010
001
100
010
011
010
101
011
100
011
110
4
1
2
1
8
2
4
2
16
4
8
4
32
8
16
8
64
00
10
01
11
00
10
01
11
00
10
01
11
00
10
01
11
00
PRESCALER
BITS
SELECTION
1
5
3
7
1
5
3
7
1
5
3
7
1
5
3
7
1
Transmitting and Receiving Data
All data transmitted and received by the 1-Wire bus master passes through the transmit/receive data buffer
(internal register address xxxxx001b). The data buffer is double-buffered with separate transmit and receive
buffers. Writing to the data buffer connects the transmit buffer to the data bus while reading connects the receive
buffer to the data bus.
The data buffer combination for the transmit interface is composed of the transmit buffer and transmit shift register.
Each of these registers has a flag that can be used as an interrupt source. The transmit buffer empty (TBE) flag is
set when the transmit buffer is empty and ready to accept a new byte of data from the user. As soon as the data
byte is written into the transmit buffer, TBE is cleared. The transmit shift register empty (TEMT) flag is set when the
shift register has no data and is ready to load a new data byte from the transmit buffer. When a byte of data is
transferred into the transmit shift register, TEMT is cleared and TBE becomes set.
To send a byte of data on the 1-Wire bus, the user writes the desired data to the transmit buffer. The data is moved
to the transmit shift register, where it is shifted serially onto the 1-Wire bus, least significant bit first. When the
transmit shift register is empty, new data is transferred from the transmit buffer (if available) and the serial process
repeats. Note that the 1-Wire protocol requires a reset before any bus communication.
The data buffer combination for the receive interface is composed of the receive buffer and the receive shift
register. The receive registers can also generate interrupts. The receive shift register full (RSRF) flag is set at the
start of data being shifted into the register, and is cleared when the receive shift register is empty. The receive
buffer full (RBF) flag is set when data is transferred from the receive shift register into the receive buffer and is
cleared after the CPU reads the register. If RBF is set, and another byte of data is received in the receive shift
84 of 97
DS80C400 Network Microcontroller
register, the receive shift register holds the new byte and waits until the user reads the receive buffer, clearing the
RBF flag. Thus, if both RSRF and RBF are set, no further transmissions should be made on the 1-Wire bus, or else
data can be lost, as the byte in the receive shift register is overwritten by the next received data.
To read data from a slave device, the bus master must first be ready to transmit data depending on commands in
the command register already set up by the CPU. Data is retrieved from the bus in a similar fashion to a write
operation. The CPU initiates a read operation by writing FFh data to the transmit buffer. The data that is then
shifted into the receive shift register is the wired-AND of the bus master write data (FFh) and the data from the
slave device. When the receive shift register is full, the data is transferred to the receive buffer (if RBF = 0), where
it can be read by the CPU. Additional bytes can be read by sending FFh again. If the slave device is not ready to
respond to read request, the data received the by the bus master is identical to that which was transmitted (FFh).
Bus Master Commands
The 1-Wire bus master can generate special commands on the 1-Wire bus in addition to transmitting and receiving
data. These commands are generated through the setting of a corresponding bit in the command register
(xxxxx000h). These operational modes are defined in The Book of iButton Standards available on our website at
www.maxim-ic.com/iButtonBook.
1WR (Bit 0): 1-Wire Reset. Setting this bit to logic 1 causes a reset of the 1-Wire bus, which must precede any
command given on the bus. Setting this bit also automatically clears the SRA bit. The 1WR bit is automatically
cleared as soon as the 1-Wire bus reset completes. The bus master sets the presence-detect interrupt flag (PD)
when the reset is completed and sufficient time for a 1-Wire reset to occur has passed. The result of the 1-Wire
reset is placed in the interrupt register bit PDR. If a presence-detect pulse was received, PDR is cleared; otherwise,
it is set.
SRA (Bit 1): Search ROM Accelerator. Setting this bit to logic 1 places the bus master into search-ROMaccelerator mode in order to expedite the search ROM process. The general principle of the search ROM process
is to deselect one device after another at every conflicting ROM ID bit position of the attached slave devices. Using
the search ROM process, the bus master can ultimately learn the ROM ID for each device attached to the 1-Wire
bus. To prevent the CPU from having to perform many bit manipulations during a search ROM process, the searchROM-accelerator mode can be invoked, allowing the CPU to send 16 bytes of data to complete a single search
ROM pass. Details about the search ROM algorithm can be found in The Book of iButton Standards or the HighSpeed Microcontroller User’s Guide: Network Microcontroller Supplement.
FOW (Bit 2): Force OW Line Low. Setting this bit to logic 1 forces the OW line to a low value if the EN_FOW bit in
the control register is also set to logic 1. The FOW bit has no affect on the OW line when the EN_FOW bit is
cleared to logic 0.
OW_IN (Bit 3): OW Line Input. This bit always reflects the current logic state of the OW line.
Bus Master Controls
The 1-Wire bus master can perform certain special functions to support OW line operation. These special functions
can be configured through the control register (xxxxx101h).
LLM (Bit 0): Long Line Mode. This bit is used to enable the long-line mode timing. Setting this bit to logic 1
effectively moves the ‘write one’ release and data-sample timing during standard mode communication out to 8s
and 22s, respectively. The recovery time is extended to 14s. This provides a less strict environment for long line
transmissions. Clearing this bit to logic 0 leaves the ‘write one’ release, data sampling, and recovery time (during
standard mode communication) at 5s, 15s, and 10s, respectively.
PPM (Bit 1): Presence Pulse Masking. This bit is used to enable/disable the presence pulse-masking function.
Setting this bit to logic 1 causes the bus master to initiate the beginning of a presence pulse during a 1-Wire reset.
This enables the master to prevent the larger amount of ringing caused by slave devices pulling the OW line low. If
the PPM bit is set, the PDR result bit in the interrupt flag register is always set, indicating that a slave device is
present on the OW line (even if there are none). Clearing the PPM bit to logic 0 disables the presence pulsemasking function.
85 of 97
DS80C400 Network Microcontroller
EN_FOW (Bit 2): Enable Force OW. Setting the EN_FOW bit to a logic 1 allows the bus master to force the OW
line low using FOW (bit 2 of the command register). Clearing the EN_FOW bit to a logic 0 disables the use of the
FOW bit.
STPEN (Bit 3): Strong Pullup Enable. Setting the STPEN bit to a logic 1 enables functionality for the OWSTP
output pin. The OWSTP pin serves as the enable signal to an external strong pullup device. This functionality is
used for meeting the recovery time requirement in overdrive mode and long-line standard communication. When
enabled (STPEN = 1), OWSTP goes active-low any time the master is not pulling the OW line low or waiting to read
data from a slave during a communication sequence. Once the communication sequence is complete, the OWSTP
output is released. Note that when the master is in the idle state, the STP_SPLY bit must also be set to logic 1 (in
addition to STPEN = 1) in order for the OWSTP pin to remain in the active-low state. Clearing the STPEN bit to
logic 0 disables all OWSTP pin functionality.
STP_SPLY (Bit 4): Strong Pullup Supply Mode. When the OWSTP pin is enabled (STPEN = 1), setting the
STP_SPLY bit to logic 1 results in an active-low output for the OWSTP pin being sustained when the master is in an
idle state. Thus, when the OWSTP signal gates an external P-channel pullup, STP_SPLY = 1 can be used to
enable a stiff supply voltage to slave devices requiring high current during operation. Clearing the bit to logic 0
disables the strong pullup on the OWSTP pin when the master is idle. This bit has no affect when the OWSTP pin is
disabled (STPEN = 0).
BIT_CTL (Bit 5): Bit-Banging Mode. Setting this bit to logic 1 place the master into the bit-banging mode of
operation. In the bit-banging mode, only the least significant bit of the transmit/receive register is sent or received
before the associated interrupt flag occurs (signaling the end of the transaction). Clearing the bit leaves the bus
master operating in full-byte boundaries.
OD (Bit 6): Overdrive Mode. Setting this bit to a logic 1 places the master into overdrive mode, effectively
changing the bus master timing to match the 1-Wire timing for overdrive mode as outlined in The Book of iButton
Standards. Clearing the OD bit to a logic 0 leaves the master operating with standard mode timing.
EOWMI (Bit 7): Enable 1-Wire Master Interrupt. Setting this bit to a logic 1 enables the 1-Wire master interrupt
request to the CPU for any of the 1-Wire interrupt sources that have been individually enabled in the interrupt
enable register (xxxxx011b). Since the 1-Wire master interrupt and external interrupt 5 share the same interrupt
flag (IE5; EXIF.7), both cannot be used simultaneously. Thus, enabling the 1-Wire interrupt source effectively
disables the external interrupt 5 source.
1-Wire Interrupts
The 1-Wire bus master can be configured to generate an interrupt request to the CPU on the occurrence of a
number of 1-Wire-related events or conditions. These include the following: presence-detect, transmit buffer empty,
transmit shift-register empty, receive buffer full, receive shift-register full, 1-Wire short, and 1-Wire low. Each of
these potential 1-Wire interrupt sources has a corresponding enable bit and flag bit. Each flag bit in the interrupt
flag register (xxxxx010b) is set, independent of the interrupt enable bit, when the associated event or condition
occurs. In order for the interrupt flag to generate an interrupt request to the CPU, however, the individual enable bit
for the source along with the 1-Wire bus master interrupt enable bit (EOWMI; control register bit 7), and global
interrupt enable bit (EA; IE.7) must both be set to a logic 1. To clear the 1-Wire bus master interrupt, a read of the
interrupt flag register must always be performed by software. Table 24 summarizes the 1-Wire bus master interrupt
sources.
86 of 97
DS80C400 Network Microcontroller
Table 24. 1-Wire Bus Master Interrupt Sources
INTERRUPT
SOURCE
Presence Detect
Transmit Buffer
Empty
Transmit Shift
Register Empty
Receive Buffer Full
Receive Shift
Register Full
1-Wire Short
1-Wire Low
ENABLE/FLAG LOCATION
(Interrupt Flag Register.x
Interrupt Enable Register.x)
MEANING
After a 1-Wire reset has been issued, this flag is set after the amount
of time for a presence-detect pulse to have occurred. This bit is cleared
when the interrupt flag register is read.
This flag is set when the transmit buffer is empty and ready to receive
the next byte. This bit is cleared when data is written to the transmit
buffer. A read of the interrupt flag register has no effect on this bit.
This flag is set when the transmit shift register is empty and is ready to
load a new byte from the transmit buffer. This bit is cleared when data
is transferred from the transmit buffer to the transmit shift register. A
read of the interrupt flag register has no effect on this bit.
This flag is set when there is a byte of data in the receive buffer waiting
to be read. This bit is cleared when the receive buffer is read.
This flag is set when there is a byte of data in the receive shift register
waiting to be transferred to the receive buffer. This bit is cleared when
data in the receive shift register is transferred to the receive buffer.
This flag is set when the OW line was low before the bus master was
able to send out the beginning of a reset or a time slot. A read of the
interrupt flag register clears this bit.
This flag is set when the OW line is low while the bus master is idle,
signaling that a slave device has issued a presence pulse on the OW
line. A read of the interrupt flag register clears this bit if the OW line is
no longer low while the master is idle.
Bit 0
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Peripheral Overview (Primary Integrated System Logic)
The DS80C400 provides several of the most commonly needed peripheral functions in microcomputer-based
systems. The DS80C400 offers three serial ports, four timers, a programmable watchdog timer, power-fail reset
detection, and a power-fail interrupt flag. In addition, the microcontroller contains a CAN module for industrial
communication applications. Each of these peripherals is described below, and more details are available in the
High-Speed Microcontroller User’s Guide and the High-Speed Microcontroller User’s Guide: Network
Microcontroller Supplement.
Serial Ports
The microcontroller provides a serial port (UART) that is identical to the 80C52. Two additional hardware serial
ports are provided that are duplicates of the first one. This second port optionally uses pins P1.2 (RXD1) and P1.3
(TXD1). The third port optionally uses pins P6.6 (RXD2) and P6.7 (TXD2). The function of each of the three serial
ports is controlled by the SFRs and bits shown in Table 25.
Table 25. Serial Port SFRs
SERIAL PORT
FUNCTION CONTROL
Control Register
Input/Output Data Buffer
Baud Rate Doubler Bit
Framing Error-Detection Enable
Slave Address Mask Enable
Slave Address
SERIAL PORT 0
SERIAL PORT 1
SERIAL PORT 2
SCON0
SBUF0
PCON.7
PCON.6
SADEN0
SADDR0
SCON1
SBUF1
WDCON.7
PCON.6
SADEN1
SADDR1
SCON2
SBUF2
T3CM.4
PCON.6
SADEN2
SADDR2
All three serial ports can operate simultaneously and be configured for different baud rates or different modes.
When using a timer for the purpose of baud rate generation, serial port 1 must use timer 1, serial port 2 must use
timer 3, while serial port 0 can use either timer 1 or timer 2. Refer to the High-Speed Microcontroller User Guide for
full descriptions of serial port operational modes.
87 of 97
DS80C400 Network Microcontroller
Timers
The microcontroller provides four general-purpose timer/counters. Timers 0, 1, and 3 have three common modes of
operation. Each of the three can be used as a 13-bit timer/counter, 16-bit timer/counter, or 8-bit timer/counter with
auto-reload. Timer 0 can also operate as two 8-bit timer/counters. When operated as a counter, timers 0, 1, and 3
count pulses on the corresponding T0, T1, and T3 external pins. Timer 2 is a true 16-bit timer/counter with several
additional operating modes. With a 16-bit reload register, timer 2 supports other features such as 16-bit autoreload, capture, up/down count, and output clock generation. All four timer/counters default to the standard
oscillator frequency divided by 12 input clock but can be configured to run from the system clock divided by 4.
Timers 1 and 2 can also be configured to operate with an input clock equal to the system clock divided by 13.
Table 26 shows the SFRs and bits associated with the four timer/counters.
Table 26. Timer/Counter SFRs
TIMER/COUNTER FUNCTION
Timer/Counter Mode Selection and
Control
Count Registers
8-Bit Reload Register
16-Bit Reload/Capture Registers
Timer Input Clock-Select Bit
Divide-by-13 Clock-Option Bit
TIMER/
COUNTER 0
TIMER/
COUNTER 1
TIMER/
COUNTER 2
TIMER/
COUNTER 3
TMOD, TCON
TMOD, TCON
T2MOD, T2CON
T3CM
TH0, TL0
TH1, TL1
TH2, TL2
TH3, TL3
TH0
TH1
—
TH3
—
—
RCAP2H, RCAP2L
—
CKCON.3
CKCON.4
CKCON.5
T3CM.5
—
T2MOD.4
T2MOD.3
—
Watchdog Timer
The watchdog is a free-running, programmable timer that can set a flag, cause an interrupt, and/or reset the
microcontroller if allowed to reach a preselected timeout. It can be restarted by software.
A typical application uses the watchdog timer as a reset source to prevent software from losing control. The
watchdog timer is initialized, selecting the timeout period and enabling the reset and/or interrupt functions. After
enabling the reset function, software must then restart the timer before its expiration or hardware resets the CPU.
In this way, if the code execution goes awry and software does not reset the watchdog as scheduled, the
microcontroller is put in reset, a known good state.
Software can select one of four timeout values as controlled by the WD1 and WD0 bits. Timeout values are precise
since they are a function of the crystal frequency. When the watchdog times out, the watchdog interrupt flag (WDIF
= WDCON.3) is set. If the watchdog interrupt source has been enabled, program execution immediately vectors to
the watchdog timer interrupt-service routine (code address = 63h). To enable the watchdog interrupt source, both
the EWDI (EIE.4) and EA (IE.7) bits must be set. Furthermore, setting the EWT (WDCON.1) bit allows the
watchdog timer to generate a reset exactly 512 system clocks following a timeout. To prevent the watchdog reset
from occurring in such a situation, the watchdog timer count must be reset (RWT = 1) or the watchdog-reset
function itself must be disabled (EWT = 0). Both the enable watchdog timer (EWT) reset and the reset watchdog
timer (RWT) control bits are protected by timed-access circuitry. This prevents errant software from accidentally
clearing or disabling the watchdog. When a watchdog timer reset condition occurs, the watchdog timer reset flag
(WTRF = WDCON.2) is set by the hardware. This flag can then be interrogated following a reset to determine
whether the reset was caused by the watchdog timer.
The watchdog interrupt is useful for systems that do not require a reset circuit. It sets the WDIF (watchdog
interrupt) flag 512 system clocks before setting the reset flag. Software can optionally enable this interrupt source,
which is independent of the watchdog-reset function. The interrupt is commonly used during the debug process to
determine where watchdog reset commands must be located in the application software. The interrupt also can
serve as a convenient time-base generator or can wake up the microcontroller from power-saving modes.
The watchdog timer is controlled by the clock control (CKCON) and the watchdog control (WDCON) SFRs.
CKCON.7 and CKCON.6 are WD1 and WD0 respectively, and they select the watchdog timeout period. Of course,
the 4X/2X (PMR.3) and CD1:0 (PMR.7:6) system clock control bits also affect the timeout period. Table 27 shows
the selection of timeout.
88 of 97
DS80C400 Network Microcontroller
Table 27 demonstrates that, for a 40MHz crystal frequency, the watchdog timer is capable of producing timeout
periods from 3.28ms (217 x 1/40MHz) to greater than one and a half seconds (1.68 = 226 x 1/40MHz) with the
default setting of CD1:0 (= 10). This wide variation in timeout periods allows very flexible system implementation.
In a typical initialization, the user selects one of the possible counter values to determine the timeout. Once the
counter chain has completed a full count, hardware sets the interrupt flag (WDIF = WDCON.3). Regardless of
whether the software makes use of this flag, there are then 512 system clocks left until the reset flag (WTRF =
WDCON.2) is set. Software can enable (1) or disable (0) the reset using the enable watchdog timer reset (EWT =
WDCON.1) bit.
Table 27. Watchdog Timeout Values
4X/2X CD1:0
1
0
x
x
x
00
00
01
10
11
WD1:0 = 00
215
216
217
217
225
WATCHDOG INTERRUPT TIMEOUT
WD1:0 = 01
WD1:0 = 10
218
221
219
222
20
2
223
20
2
223
28
2
231
WD1:0 = 11
224
225
226
226
234
IrDA Clock
The DS80C400 has the ability to generate an output clock (CLKO) as a secondary function on port pin P3.5.
Setting both the IrDA clock-output enable bit (IRDACK:COR.7) and external clock-output enable bit
(XCLKOE:COR.1) to a logic 1 produces an output clock of 16 times the programmed baud rate for serial port 0.
This 16X output clock used in conjunction with serial port 0 I/O (TXD0, RXD0) conveniently allows for direct
connection to common IrDA encoder/decoder devices. If the XCLKOE bit alone is set to logic 1, the CLKO pin
outputs the system clock frequency divided by 2, 4, 6, or 8 as defined by clock-output divide bits (COD1:0). Setting
the IRDACK bit alone to logic 1 has no effect.
Interrupts
The microcontroller provides 16 interrupt sources with three priority levels. All interrupts, with the exception of the
power-fail interrupt, are controlled by a series combination of individual enable bits and a global interrupt enable EA
(IE.7). Setting EA to a 1 allows individual interrupts to be enabled. Clearing EA disables all interrupts regardless of
their individual enable settings.
The three available priority levels are low, high, and highest. The highest priority level is reserved for the power-fail
interrupt only. All other interrupts have individual priority bits that when set to a 1 establish the particular interrupt
as high priority. In addition to the user-selectable priorities, each interrupt also has an inherent natural priority, used
to determine the priority of simultaneously occurring interrupts. The available interrupt sources, their flags, enables,
natural priority, and available priority selection bits are identified in Table 28. Note that external interrupts 2–5 and
the 1-Wire bus master share a common interrupt vector (43h). Also note that external interrupt 5 and the 1-Wire
bus master interrupt are multiplexed to form a single interrupt request. When the 1-Wire bus master interrupt is
enabled (EOWMI = 1), it takes priority over external interrupt 5. In order for external interrupt 5 request to be used,
the 1-Wire bus master interrupt must be disabled (EOWMI = 0).
89 of 97
DS80C400 Network Microcontroller
Table 28. Interrupt Summary
NAME
FUNCTION
VECTOR
PFI
Power-Fail Interrupt
33h
NATURAL
PRIORITY
0
INT0
External Interrupt 0
03h
1
TF0
Timer 0
0Bh
2
INT1
External Interrupt 1
13h
3
TF1
Timer 1
1Bh
4
TI0 or RI0
Serial Port 0
23h
5
TF2
Timer 2
2Bh
6
TI1 or RI1
Serial Port 1
3Bh
7
INT2
INT3
INT4
External Interrupts 2–5,
1-Wire Bus Master,
Interrupt
43h
8
INT5/OWMI
—
—
—
TF3
TI2 or RI2
WPI
C0I
Timer 3
Serial Port 2
Write Protect Interrupt
CAN0 Interrupt
4Bh
53h
5Bh
6Bh
9
10
11
12
EAI
Ethernet Activity
73h
13
WDTI
EPMI
Watchdog Timer
Ethernet Power Mode
63h
7Bh
14
15
FLAG BIT
ENABLE BIT
PFI (WDCON.4)
IE0 (TCON.1)
(Note 2)
TF0 (TCON.5)
(Note 1)
IE1 (TCON.3)
(Note 2)
TF1 (TCON.7)
(Note 1)
RI_0(SCON0.0)
TI_0(SCON0.1)
TF2(T2CON.7)
RI_1(SCON1.0)
TI_1(SCON1.1)
IE2 (EXIF.4)
IE3 (EXIF.5)
IE4 (EXIF.6)
IE5 (EXIF.7)
(Note 3)
TF3 (T3CM.7))
IE4 (EXIF.6)
WPIF (MCON2.7)
Various
TIF (BCUC.5)
RIF (BCUC.4)
WDIF (WDCON.3)
EPMF (BCUC.6)
EPFI (WDCON.5)
PRIORITY
CONTROL BIT
N/A
EX0 (IE.0)
PX0 (IP.0)
ET0 (IE.1)
PT0 (IP.1)
EX1 (IE.2)
PX1 (IP.2)
ET1 (IE.3)
PT1 (IP.3)
ES0 (IE.4)
PS0 (IP.4)
ET2 (IE.5)
PT2 (IP.5)
ES1 (IE.6)
PS1 (IP.6)
EX2-5 (EIE.0)
—
—
PX2-5 (EIP.0)
EOWMI (Note 3)
ET3 (EIE.1)
ES2 (EIE.2)
EWPI (EIE.3)
C0IE (EIE.6)
PT3 (EIP.1)
PS2 (EIP.2)
PWPI (EIP.3)
C0IP (EIP.6)
EAIE (EIE.5)
EAIP (EIP.5)
EWDI (EIE.4)
EPMIE (EIE.7)
PWDI (EIP.4)
EPMIP (EIP.7)
Unless marked, all flags must be cleared by the application software.
Note 1: Cleared automatically by hardware when the service routine is entered.
Note 2: If edge-triggered, the flag is cleared automatically by hardware when the service routine is entered. If level-triggered, the flag follows the
state of the interrupt pin.
Note 3: The global 1-Wire interrupt-enable bit (EOWMI) and individual 1-Wire interrupt source enables are located in the internal 1-Wire bus
master interrupt enable register, and must be accessed through the OWMAD and OWMDR SFRs. Individual 1-Wire interrupt source
flag bits that are located in the internal 1-Wire bus master Interrupt flag register are accessed in the same way.
One’s Complement Adder
The DS80C400 implements a one’s complement adder to support the Internet checksum algorithm. The adder
contains a 16-bit accumulator and is accessed through the one’s complement adder data (OCAD) SFR.
Writing two bytes to the OCAD register initiates a summation between the 16-bit accumulator and the 16-bit value
entered. When entering a new 16-bit value for summation, the MSB should be loaded first and the LSB loaded
second. The calculation begins on the first machine cycle following the second write to the OCAD register and
executes in a single machine cycle. This allows back-to-back writes of 16-bit data to the OCAD register for
summation. The carry out bit from the high-order bit of the calculation is added back into the low-order bit of the
accumulator.
Reading two bytes from the OCAD register downloads the contents of the 16-bit accumulator. When reading the
16-bit accumulator through the OCAD register, the MSB is unloaded first and the LSB is unloaded second. The 16bit accumulator is cleared to 0000h following the second read of the OCAD SFR.
The following is an example sequence for producing an Internet checksum for transmission.



Read OCAD twice to make certain that the 16-bit accumulator = 0000h
Write MSB of 16-bit value to OCAD
Write LSB of 16-bit value to OCAD
90 of 97
DS80C400 Network Microcontroller





Repeat steps 2, 3 over the message data for which the checksum is to be computed
Read MSB of 16-bit value from OCAD
One’s complement of the byte last read is the Internet checksum MSB
Read LSB of 16-bit value from OCAD
One’s complement of the byte last read is the Internet checksum LSB
Note that the computation of the Internet checksum over the message data and 16-bit checksum field should yield
0000h.
Clock Control and Power Management
The DS80C400 includes a number of unique features that allow flexibility in selecting system clock sources and
operating frequencies. To support the use of inexpensive crystals while allowing full speed operation, a clock
multiplier is included in the microcontroller’s clock circuit. Also, in addition to the standard 80C32 idle and powerdown (stop) modes, the DS80C400 provides a PMM. This mode allows the microcontroller to continue instruction
execution at a very low speed to significantly reduce power consumption (below even idle mode). The DS80C400
also features several enhancements to stop mode that make this extremely low-power mode more useful. Each of
these features is discussed in detail below.
System Clock Control
As mentioned previously, the microcontroller contains special clock-control circuitry that simultaneously provides
maximum timing flexibility and maximum availability and economy in crystal selection. The logical operation of the
system clock divide control function is shown in Figure 20. A 3:1 multiplexer, controlled by CD1, CD0 (PMR.7-6),
selects one of three sources for the internal system clock:



Crystal oscillator or external clock source
(Crystal oscillator or external clock source) divided by 256
(Crystal oscillator or external clock source) frequency multiplied by 2 or 4 times
The system clock control circuitry generates two clock signals that are used by the microcontroller. The internal
system clock provides the time base for timers and internal peripherals. The system clock is run through a divideby-4 circuit to generate the machine cycle clock that provides the time base for CPU operations. All instructions
execute in one to five machine cycles. It is important to note the distinction between these two clock signals, as
they are sometimes confused, creating errors in timing calculations.
Setting CTM = 1 and CD1, CD0 = 00b enables the frequency multiplier, either doubling or quadrupling the
frequency of the crystal oscillator or external clock source. The 4X/2X bit controls the multiplying factor, selecting
twice or four times the frequency when set to 0 or 1, respectively. Enabling the frequency multiplier results in
apparent instruction execution speeds of 2 or 1 clocks. Regardless of the configuration of the frequency multiplier,
the system clock of the microcontroller can never be operated faster than 75MHz. This means that the maximum
external clock source is 18.75MHz when using the 4X setting, and 37.5MHz when using the 2X setting.
The primary advantage of the clock multiplier is that it allows the microcontroller to use slower crystals to achieve
the same performance level. This reduces EMI and cost, as slower crystals are generally more available and thus
less expensive.
Setting CD1, CD0 = 11b enables the PMM. When placed into PMM, the incoming crystal or clock frequency is
divided by 256, resulting in a machine cycle of 1024 clocks. Note that power consumption in PMM is less than idle
mode. While both modes leave the power-hungry internal timers running, PMM runs all clocked functions such as
timers at the rate of crystal divided by 1024, rather than crystal divided by 4. Even though instruction execution
continues in PMM (albeit at a reduced speed), it still consumes less power than idle mode. As a result, there is little
reason to use idle mode in new designs.
The system clock and machine cycle rate changes one machine cycle after the instruction changing the control
bits. Note that the change affects all aspects of system operation, including timers and baud rates. Using the
switchback feature, described later, can eliminate many of the problems associated with the PMM.
91 of 97
DS80C400 Network Microcontroller
Changing the System Clock/Machine Cycle Clock Frequency
The microcontroller incorporates a special locking sequence to ensure “glitch-free” switching of the internal clock
signals. All changes to the CD1, CD0 bits must pass through the 10 (divide-by-4) state. For example, to change
from 00 (frequency multiplier) to 11 (PMM), the software must change the bits in the following sequence: 00b =>
10b => 11b. Attempts to switch between invalid states fail, leaving the CD1, CD0 bits unchanged.
The following sequence must be followed when switching to the frequency multiplier as the internal time source.
This sequence can only be performed when the device is in divide-by-4 operation. The steps must be followed in
this order, although it is possible to have other instructions between them. Any deviation from this order causes the
CD1, CD0 bits to remain unchanged. Switching from frequency multiplier to nonmultiplier mode requires no steps
other than the changing of the CD1, CD0 bits.
1)
2)
3)
4)
5)
Ensure that the CD1, CD0 bits are set to 10, and the RGMD (EXIF.2) bit = 0.
Clear the crystal multiplier enable (CTM) bit.
Set the 4X/2X bit to the appropriate state.
Set the CTM bit.
Poll the CKRDY bit (EXIF.3), waiting until it is set to 1. This takes approximately 65,536 cycles of the external
crystal or clock source.
6) Set CD1, CD0 to 00. The frequency multiplier is engaged on the machine cycle following the write to these bits.
Figure 20. System Clock Control Diagram
Switchback
As an alternative to software changing the CD1 and CD0 clock control bits to exit PMM, the microcontroller
provides hardware alternatives for automatic switchback to standard speed (divide-by-4) operation. When enabled,
the switchback feature allows serial ports and interrupts to automatically switch back from divide-by-1024 (PMM) to
divide-by-4 (standard speed) operation. This feature makes it very convenient to use the PMM in real-time
applications.
The switchback feature is enabled by setting the SFR bit SWB (PMR.5) to a 1. Once it is enabled, and PMM is
selected, two possible events can cause an automatic switchback to divide-by-4 mode. First, if an external interrupt
occurs and is acknowledged, the system clock reverts from PMM to divide-by-4 mode. For example, if INT0 is
enabled and the CPU is not servicing a higher priority interrupt, then switchback occurs on INT0. However, if INT0
is not enabled or the CPU is servicing a higher priority interrupt, then activity on INT0 does not cause switchback to
occur.
A switchback can also occur when an enabled UART detects the start bit, indicating the beginning of an incoming
serial character or when the SBUF register is loaded initiating a serial transmission. Note that a serial character’s
start bit does not generate an interrupt. The interrupt occurs only on reception of a complete serial word. The
automatic switchback on detection of a start bit allows hardware to return to divide-by-4 operation (and the correct
baud rate) in time for a proper serial reception or transmission.
92 of 97
DS80C400 Network Microcontroller
Status
The STATUS (C5h) register and STATUS1 (F7h) register provide information about interrupt and serial port activity
to assist in determining if it is possible to enter PMM. The microcontroller supports three levels of interrupt priority:
power-fail, high, and low. The PIP (power-fail priority interrupt status; STATUS.7), HIP (high priority interrupt status;
STATUS.6), and LIP (low priority interrupt status; STATUS.5) status bits, when set to a logic 1, indicate the
corresponding level is in service.
Software should not rely on a lower-priority level interrupt source to remove PMM (switchback) when a higher level
is in service. Check the current priority service level before entering PMM. If the current service level locks out a
desired switchback source, then it would be advisable to wait until this condition clears before entering PMM.
Alternately, software can prevent an undesired exit from PMM by intentionally entering a low priority interruptservice level before entering PMM. This prevents other low priority interrupts from causing a switchback.
Entering PMM during an ongoing serial port transmission or reception can corrupt the serial port activity. To
prevent this, a hardware lockout feature ignores changes to the clock divisor bits while the serial ports are active.
Serial port transmit and receive activity can be monitored through the serial port activity bits located in the STATUS
and STATUS1 registers.
Oscillator-Fail Detect
The microcontroller contains a safety mechanism called an on-chip oscillator-fail detect circuit. When enabled, this
circuit causes the microcontroller to be held in reset if the oscillator frequency falls below ~100kHz. When
activated, this circuit complements the watchdog timer. Normally, the watchdog timer is initialized so that it times
out and causes a reset in the event that the microcontroller loses control. In the event of a crystal or external
oscillator failure, however, the watchdog timer does not function, and there is the potential to fail in an uncontrolled
state. Using the oscillator-fail detect circuit forces the microcontroller to a known state (i.e., reset) even if the
oscillator stops.
The oscillator-fail detect circuitry is enabled when software sets the enable bit OFDE (PCON.4) to a 1. Please note
that software must use a timed-access procedure (described earlier) to write this bit. The OFDF (PCON.5) bit also
sets to a 1 when the circuitry detects an oscillator failure, and the microcontroller is forced into a reset state. This
bit can only be cleared to a 0 by a power-fail reset or by software. The oscillator-fail detect circuitry is not triggered
when the oscillator is stopped upon entering stop mode.
Power-Fail Reset
The microcontroller incorporates an internal precision bandgap voltage reference and comparator circuit that
provide a power-on and power-fail reset function. This circuit monitors the incoming power supply voltages (VCC1
and VCC3) and holds the microcontroller in reset if either supply is below a minimum voltage level. When power
exceeds the reset threshold, a full power-on reset is performed. In this way, this internal voltage monitoring circuitry
handles both power-up and power-down conditions without the need for additional external components.
Once VCC1 and VCC3 have risen above minimum voltages, VRST1 and VRST3 respectively, the device automatically
restarts the oscillator for the external crystal and counts 65,536 clock cycles before program execution begins at
location 0000h. This helps the system maintain reliable operation by only permitting operation when the supply
voltage is in a known good state. Software can determine that a power-on reset has occurred by checking the
power-on reset flag (POR;WDCON.6). Software should clear the POR bit after reading it.
Power-Fail Interrupt
The bandgap voltage reference that sets precise reset thresholds also generates an optional early warning powerfail interrupt (PFI). When enabled by software, the microcontroller vectors to code address 0033h if either VCC1 or
VCC3 drop below VPFW1 or VPFW3, respectively. PFI has the highest priority. The PFI enable is in the watchdog
control SFR (EPFI;WDCON.5). Setting this bit to logic 1 enables the PFI. Application software can also read the
PFI flag at WDCON.4. A PFI condition sets this bit to a 1. The flag is independent of the interrupt enable and must
be cleared by software.
93 of 97
DS80C400 Network Microcontroller
External Reset Pins
The DS80C400 has both reset input (RST) and reset output (RSTOL) pins. The RSTOL pin supplies an active-low
reset output when the microcontroller is reset through a high on the RST pin, a timeout of the watchdog timer, a
crystal oscillator fail, or an internally detected power-fail. The timing of the RSTOL pin is dependent on the source
of the reset.
RESET TYPE/SOURCE
Power-On Reset
External Reset
Power-Fail
Watchdog Timer Reset
Oscillator-Fail Detect
RSTOL DURATION
65,536 tCLK (as described in Power Cycle Timing Characteristics)
< 1.25 machine cycles
65,536 tCLK (as described in Power Cycle Timing Characteristics)
Two machine cycles
65,536 tCLK (as described in Power Cycle Timing Characteristics)
Note: When connecting the DS80C400 to an external PHY, do not connect the RSTOL to the reset of the PHY.
Doing so may disable the Ethernet transmit.
Idle Mode
Setting the IDLE bit (PCON.0) invokes the idle mode. Idle leaves internal clocks, serial ports, and timers running.
Power consumption drops because memory is not being accessed and instructions are not being executed. Since
clocks are running, the idle power consumption is a function of crystal frequency. The CPU can exit idle mode with
any interrupt or a reset. Because PMM consumes less power than idle mode, and leaves the timers and CPU
operating, idle mode is no longer recommended for new designs, and is included for backward-software
compatibility only.
Stop Mode
Setting the STOP bit of the power-control register (PCON.1) invokes stop mode. Stop mode is the lowest power
state (besides power off) since it turns off all internal clocking. All microcontroller operation ceases at the end of the
instruction that sets the STOP bit. The CPU invokes stop mode only when the CAN controller has been disabled
(through the SWINT or CRST bits in the C0C SFR) and when the Ethernet controller has been placed in sleep
mode. The CPU can exit stop mode through an external interrupt, Ethernet power-mode interrupt, CAN interrupt, or
a reset condition. Internally generated interrupts (timer, serial port, watchdog) cannot cause an exit from stop mode
because internal clocks are not active in stop mode. See the DC Electrical Specifications section for ICC1 and ICC3
maximum stop mode currents.
Bandgap Select
The DS80C400 provides two enhancements to stop mode. As described below, the device provides a bandgap
reference to determine power-fail interrupt and reset thresholds. The bandgap reference is controlled by the
bandgap select bit, BGS (EXIF.0). Setting BGS to a 1 keeps the bandgap reference enabled during stop mode.
The default or reset condition of the bit is logic 0, which disables the bandgap during stop mode. This bit does not
enable/disable the internal reference during full power, PMM, or idle modes.
With the bandgap reference enabled, the power-fail reset and power-fail interrupt sources are valid means for
leaving stop mode. This allows software to detect and compensate for a power supply sag or brownout, even when
in stop mode. When BGS = 1, the internal bandgap and associated comparator circuitry consume a small amount
of additional current during stop mode. If a user does not require a power-fail reset or interrupt while in stop mode,
the bandgap can remain disabled. Only the most power-sensitive applications should disable the bandgap
reference in stop mode, as this results in an uncontrolled power-down condition.
Ring Oscillator
The second enhancement to stop mode reduces power consumption and allows the device to restart instantly
when exiting stop mode. The ring oscillator is an internal clock that can optionally provide the clock source to the
microcontroller when exiting stop mode in response to an interrupt.
During stop mode the crystal oscillator is halted to maximize power savings. Typically 1ms to 7ms are required for
an external crystal to begin oscillating again once the device receives the exit stimulus. The ring oscillator, by
contrast, is a free-running digital oscillator that has no startup delay. The ring oscillator feature is enabled by setting
the ring oscillator select bit, RGSL (EXIF.1). If enabled, the microcontroller uses the ring oscillator as the clock
94 of 97
DS80C400 Network Microcontroller
source to exit stop mode, resuming operation in less than 100ns. After 65,536 oscillations of the external clock
source (not the ring oscillator), the device clears the ring oscillator mode bit, RGMD (EXIF.2), to indicate that the
device has switched from the ring oscillator to the external clock source.
The ring oscillator runs at approximately 15MHz, but varies over temperature and voltage. As a result, no serial
communication or precision timing should be attempted while running from the ring oscillator, since the operating
frequency is not precise. Likewise, the Ethernet and CAN controllers derive their timing from the system clock and
should not be enabled until RGMD = 0. The reset (default) state of the RGSL bit is logic 0, which does not result in
use of the ring oscillator to exit stop mode.
EMI Reduction
One of the major contributors to radiated noise in an 8051-based system is the toggling of ALE. The microcontroller
allows software to disable ALE when not used by setting the ALEOFF (PMR.2) bit to a 1. When ALEOFF = 1, ALE
automatically toggles during off-chip program and data memory accesses. However, ALE remains static when
performing on-chip memory access. The default state of ALEOFF is 0, so ALE normally toggles at a frequency of
XTAL/4.
Software Breakpoint Mode
The DS80C400 provides a special software-breakpoint mode for code-debug purposes. Breakpoint mode can be
enabled by setting the BPME bit (ACON.4) to a logic 1. Once enabled, the A5h op code can be used to create a
break in code execution. When the break op code (A5h) is executed, all clocks to the timer 0, 1, 2, 3, and watchdog
timer blocks are stopped and any serial port operation (when derived from a timer) is halted. Additionally, the state
machine controlling access to timed-access-protected SFRs is suspended. Much like an interrupt, the CPU
generates a hardware LCALL and vector to address location 000083h. Unlike an interrupt, however, the return
address is not pushed onto the stack, but is placed into the BPA1 (LSB), BPA2 (MSB), and BPA3 (XSB) SFRs, and
the A5h op code is used to exit breakpoint mode and return to the address contained in the BPA3:1 SFRs.
95 of 97
DS80C400 Network Microcontroller
PIN CONFIGURATION
TOP VIEW
100
76
1
75
Maxim
DS80C400
25
51
50
26
LQFP
PACKAGE INFORMATION
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
100 LQFP
—
21-0297
96 of 97
DS80C400 Network Microcontroller
REVISION HISTORY
REVISION
NUMBER
REVISION
DATE
0
111202
DESCRIPTION
New product release.
—
Replaced “DS2502U-E48” with “DS2502-E48.”
1
2
060203
102103
111704
14
Added note for connecting the PHY to the DS80C400: “When connecting the
DS80C400 to an external PHY, do not connect the RSTOL to the reset of the
PHY. Doing so may disable the Ethernet transmit.”
29, 49, 60,
94
Updated Figure 12: ROM Code Boot Sequence flowchart.
70
Corrected PSEN signal in the “Nonmultiplexed, 2-Cycle Data Memory CE0-7
Write” timing diagram.
18
060805
33, 40, 41,
42, 47, 51,
52, 69, 71,
73, 74, 75,
79
Modified Figure 12: ROM Code Boot Sequence to better explain action of the
DS80C400 when it is searching for ROM code.
70
Added lead-free part to Ordering Information table.
Added notes explaining that the system clock must be > 25MHz to support
Ethernet 100Mbps mode.
5
6
7
010907
061908
6/09
82, 90
Clarified where appropriate the operation of the device when ROM is disabled;
clarified the system requirements when using TINI ROM firmware.
High-Speed Microcontroller User’s Guide: DS80C400 Supplement was changed
to High-Speed Microcontroller User’s Guide: Network Microcontroller
Supplement in all instances.
4
69, 72
MOVX Characteristics (Nonmultiplexed Address/Data Bus) table: Moved MIN
spec for tPXIZ to MAX column.
Corrected PT2/PT3 references in Table 21 and Table 28.
3
PAGES
CHANGED
1, 34, 72, 75,
78, 79, 80,
85, 87
1
49, 69
Corrected BCUD SFR address in Buffer Control Unit section.
50
Updated package drawing.
97
In the Pin Description, replaced the Port 4 description to match the SFR
description in the High-Speed Microcontroller User’s Guide: Network
Microcontroller Supplement.
30
Updated Figure 12 to clarify operation when no user code was found.
70
Corrected the SEL (DPS.3) bit reset state from 1 to 0 in Table 2.
38
97 of 97
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim
reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.