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PDF COM20051 Data sheet ( Hoja de datos )
| Número de pieza | COM20051 | |
| Descripción | Integrated Microcontroller and ARCNET (ANSI 878.1) Interface | |
| Fabricantes | SMSC Corporation | |
| Logotipo |  |
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COM20051
www.DataSheet4U.com
Integrated Microcontroller and
ARCNET (ANSI 878.1) Interface
FEATURES
• High Performance/Low Cost
• Microcontroller Based on Popular 8051
Architecture
• Intel 8051 Instruction Set Compatible
• Drop-In Replacement for 80C32 PLCC
• Network Supports up to 255 Nodes
• Powerful Network Diagnostics
• Maximum 507 Byte Packets
• Duplicate Node ID Detection
• Self-Configuring Network Protocol
• Retains all 8051 Peripherals Including Serial
I/O and Two Timers
• Utilizes ARCNET Token Bus Network
Engine
• Requires No Special Emulators
• 5 Mbps to 156 Kbps Network Data Rate
• Network Interface Supports RS-485, Twisted
Pair, Coaxial, and Fiber Optic Interfaces
• Receive All Mode Allows Any Packet to Be
Received
GENERAL DESCRIPTION
The COM20051 is a low-cost, highly-integrated
microcontroller incorporating a high-performance
network controller based on the ARCNET Token
Bus Standard (ANSI 878.1). The COM20051 is
based around the popular Intel 8051
architecture. The device is implemented using a
microcontroller core compatible with the Intel
80C32 ROMless version of the 8051
architecture. The COM20051 is ideal for
distributed control networking applications such
as those found in industrial/machine controls,
building/factory automation, consumer products,
instrumentation and automobiles.
The COM20051 contains many features that are
beneficial for embedded control applications.
The microcontroller is a fully-functional 16MHz
80C32 that is comparable to the Intel 80C32 with
2 timers. In contrast to other embedded
controller/networking solutions, the COM20051
adds a fully-featured, robust, powerful, and
simple network interface while retaining all of the
basic 8051 peripherals, such as the serial port
and counter/timers.
In addition, the COM20051 supports an
Emulation Mode that permits the use of a
standard 80C32 emulator in conjunction with the
COM20051 to develop software drivers for the
network core. ARCNET core is mapped to a
256-byte page of the External Data Memory
Space of the 80C32.
This
1 page  
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
NAME
23 nPulse 2
SYMBOL
nPULSE2
DESCRIPTION
Output. Network output. Outputs a synchronous
clock at 2x the data rate when backplane mode is
invoked.
24-31
P2.0-2.7
P2.0-2.7
Input/Output. Port 2 of the 8051. High order address
bus.
32 nProgram Store nPSEN
Enable
Output.
33 Address Latch ALE
Enable
Output.
34 Transmit Enable TXEN
Output. This signal is used to enable the drivers for
transmitting. The polarity of this signal is
programmable by grounding the nPULSE2 pin prior
to the POWER-UP.
nPULSE2 floating prior to the power-up = TXEN
active high
nPULSE2 grounded prior to the power-up = TXEN
active low. (This option is available only in the
Backplane mode).
35
nEnable
nEA
36-43
44
P0.7-0.0
P0.7-0.0
Power Supply VCC
Input. When high, causes the 8051's outputs to tri-
state. When low, allows the 8051 to address external
memory. Must be low to execute code from the
embedded 8051.
Input/Output. Port 0 of the 8051. Multiplexed low
order address/data bus.
+5V power supply.
RESET CIRCUIT FOR THE COM20051
The power on reset circuit for the COM20051 should be designed to provide a clean, fast transition time
TTL input to the COM20051. Sufficient signal high time on RST (pin 10) should be provided after Vcc
reaches +5V DC. The following circuit, which provides an 8ms power-on reset pulse, is recommended:
Vcc (+5V)
22 uF/
10V
RST (PIN 10)
220 74LS14
5
5 Page 
Reconfigure
Timer has
Timed Out
Power On
Send
Reconfigure
Burst
Read Node ID
Write ID to
RAM Buffer
Set NID=ID
1
Start
Reconfiguration
Timer (840 mS)
Y
Invitation
N
to Transmit to
this ID?
NY
TA?
Broadcast?
Y
Send
Packet
N
Transmit
NAK
Transmit
ACK
Was Packet
Broadcast?
Y
Y
Y RI?
Free Buffer
Enquiry to
this ID?
N
N
YN
SOH?
YN
RI?
Transmit
Free Buffer
Enquiry
N
YN
ACK?
No
Activity
for 74.7
us?
YN
NAK?
Write SID
to Buffer
Y
Set TA
DID Y
=0?
N
DID
=ID?
YN
Broadcast
Enabled?
Y
N
N
No
Activity
Y
for 74.7
us?
N
Set TA
NY
ACK?
Set TMA
Increment
NID
1
Y
No
Activity
for 74.7
us?
Write Buffer
with Packet
Pass the
Token
CRC N
N OK?
Y
LENGTH
OK?
Y
N
- ID refers to the identification number of the ID assigned to this node.
- NID refers to the next identification number that receives the token after
after this ID passes it.
- SID refers to the source identification.
- DID refers to the destination identification.
- SOH refers to the start of header character; preceeds all data packets.
Note*: Time values pertain to the default 2.5 Mbps operation
DID
=0?
N
Y
DID
=ID?
Y
N
SEND ACK
Set RI
No Activity
for 82
uS?
Y
Set NID=ID
N
Start Timer:
T=(255-ID)
x 146 us
Activity
On Line?
N
N
T=0?
Y
Y
FIGURE 3 - DETAILED ARCNET CORE OPERATION
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet COM20051.PDF ] | |
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