Freescale Semiconductor, Inc.
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MC68EN302/D
MC68EN302
Product Brief
Integrated Multiprotocol Processor with Ethernet
Freescale Semiconductor, Inc...
Freescale
introduces a version of the well-known MC68302 Integrated Multiprotocol Processor (IMP) with
Ethernet and DRAM controllers. It is known as the MC68EN302, and expands a family of devices based on the
MC68302.
The Ethernet controller has a 16-bit interface, resides on the 68000 bus and provides complete IEEE 802.3
compatibility. The programming model is adopted from the standard 68302 programming model. The DRAM
controller is adopted from the MC68306 product. It is enhanced to support both parity and external bus masters.
The MC68EN302 is packed in a low profile 144 TQFP.
MC68EN302
MC68302
1 GENERAL-
PURPOSE
DMA
CHANNEL
3 TIMERS
AND
ADDITIONAL
FEATURES
INTERRUPT
CONTROLLER
JTAG
IEEE 1149.1
68000
MC68000
SYSTEM BUS
6 DMA
CHANNELS
1152 BYTES
DUAL-PORT
RAM
PERIPHERAL
BUS
MODULE BUS
CONTROLLER
MICROCODED
COMMUNICATIONS
CONTROLLER
(RISC)
OTHER
SERIAL
CHANNELS
ETHERNET
CONTROLLER
3 SERIAL
CHANNELS
DRAM
CONTROLLER
Figure 1. MC68EN302 Block Diagram
This document contains information on a product under development.
Freescale
reserves the right to change or discontinue this product without notice.
SEMICONDUCTOR PRODUCT INFORMATION
©
1995
For More Information On This Product,
Go to: www.freescale.com
Freescale Semiconductor, Inc.
FEATURE LIST
The following features are incorporated into the MC68EN302 device:
• Full Complement of Existing Three SCC’s Plus Ethernet Channel
• Ethernet Channel Fully Compliant with IEEE 802.3 Specification.
• Supports Data Rates up to 10 Mbps.
• Supports the “68302” Style Programming Model.
• On-Chip Descriptors Lower Processor Bus Bandwidth Requirements.
• Separate 128 Byte FIFOs for Transmit and Receive.
• Automatic Internal Retransmission (which Frees the Processor Bus).
• Automatic Internal Flushing of Receive FIFO During Collisions (which Frees the Processor Bus).
• Dynamic Bus Sizing Support for 8-Bit Devices
• Glueless Dynamic RAM Controller without External Bus Master
• Address Muxing Support for External Bus Masters Using DRAM Controller
• Fully IEEE 1149.1 JTAG Compliant
• 144 TQFP Package for Up to 25 MHz
Freescale Semiconductor, Inc...
ETHERNET CONTROLLER
The Ethernet controller consists of a Ethernet protocol core, transmit and receive FIFOs, and a 16-bit wide
data/control interface to a 68000 bus (refer to Figure 2). The Ethernet protocol core (EPC) provides
compatibility with the IEEE 802.3 Ethernet standard. The transmit and receive FIFOs allow automatic handling
of collisions and collision fragments by the EPC, and they also provide for bus latency that can be encountered
by the DMA channels. Separate DMA channels are used for transmit and receive data paths. A dual-port RAM
is used for the on-chip buffer descriptors. A buffer descriptor control (BDC) block updates the buffer
descriptors. Control status registers are used for direct control of all of the blocks in the Ethernet controller.
ETHERNET FEATURES
• Does Not Affect Performance of Existing SCCs
• 802.3 MAC Layer Support
• Compatible with 68160 EEST (Twisted Pair/AUI)
• Two Dedicated Ethernet DMA channels, Transmit and Receive
• Full-Duplex (Switched) Ethernet Support
• Up to 10 Mb/s Operation (20 Mb/s Full-Duplex)
• 128-Byte FIFO on both Transmit and Receive
• No CPU or Bus Overhead Required on Rx or Tx Frame Collisions
• 64 entry CAM with Hash Option
• 128 internal Buffer Descriptors
• Performs Framing Functions
MC68EN302 PRODUCT INFORMATION
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• Full Collision Support
• Receives Back-to-Back Frames
• Detection of Receive Frames That Are Too Long
• Multi-Buffer Data Structure
• Supports 48-Bit Addressing
• Heartbeat Indication
• Transmitter Network Management and Diagnostics
• Receiver Network Management and Diagnostics
• Loopback Mode for Testing
• Non-Aggressive Deferral Option
• Heartbeat Status and Interrupt Option
• Graceful Stop Command
Freescale Semiconductor, Inc...
MODULE BUS
CONTROL
STATUS
REGISTERS
DESCRIPTOR
DUAL-PORT
RAM
2 DMA
CHANNELS
BUFFER
DESCRIPTOR
CONTROL
SYSTEM
INTERFACE
TRANSMIT
STATUS
TRANSMIT
FIFO
RECEIVE
FIFO
ETHERNET
PROTOCOL
ADDRESS
RECOGNITION
DUAL-PORT
RAM
ETHERNET
PROTOCOL
CORE
EEST INTERFACE
Figure 2. Ethernet Controller Block Diagram
MC68EN302 PRODUCT INFORMATION
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Freescale Semiconductor, Inc.
MODULE BUS CONTROLLER
The MC68EN302 module bus controller provides basic interface capabilities to the module bus as well as basic
system responsibilities. The features of the module bus controller are:
• Interface Between Internal 68000 bus and the Module Bus.
• Provision for Dynamic Bus Sizing, Using the Chip Select Logic of the 68302 Core.
• Handling of Interrupts for the Ethernet Controller and DRAM Controller.
• Coordination of Bus Mastership from External Sources, the Module Bus, and the MC68EN302 Core.
INTERNAL
Freescale Semiconductor, Inc...
302 BUS
MC68EN302
B
U
F
F
E
R
S
INTERNAL
68000 BUS
P
A
D
S
EXTERNAL
68000 BUS
MODULE
BUS
CONTROLLER
MODULE BUS
ETHERNET AND
DRAM CONTROLLER
Figure 3. BusStructure
DRAM CONTROLLER
• Provides two CAS lines
• Provides two RAS lines (two banks supported)
• DRAM address multiplexing on standard address bus
• Programmable up to three wait states
• 100 nS DRAM for zero wait states at 20 MHz
• 80 nS DRAM for zero wait states at 25 MHz
• CAS before RAS refresh and refresh support during system reset
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• Programmable refresh period and pre-charge period
• RAS lines are separate from the four chip selects
• Refresh hidden from bus accesses
• Write protect option
• Each bank programmable size from 128Kbytes to 8Mbytes
ADDRESS 23–ADDRESS 0
BLOCKHIT0
ADDRESS
MULTIPLEXING
DRAM ADDRESS
BLOCKHIT1
Freescale Semiconductor, Inc...
ADDRESS
DECODE
AS
UDS
LDS
R/W
CLK
RAS/CAS
GENERATION
AMUX
RAS1, RAS0
CAS1, CAS0
DRAM_RW
RFRESH
TIMER
Figure 4. DRAM Controller
MC68EN302 APPLICATIONS
The MC68EN302 is intended for low-end bridge and router applications. It has the three SCCs from the
MC68302, plus an additional Ethernet interface giving it a total of four serial interfaces.
Since the MC68EN302 has both the three SCCs as well as an Ethernet interface, it would be an excellent
choice in an ISDN to Ethernet router.
For remote access dial-in, the MC68EN302 could be used in a dial-up modem that would connect to an
Ethernet LAN.
• Low End Bridges
MC68EN302 PRODUCT INFORMATION
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