Multiprocessor
EMT355-Microcontroller
Week 14
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Outline
• Introduction
• Serial Communication
• Serial Communication Protocols
• Master/Slave
• Network Configuration
• Distributed System
• Case study
• Summary
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Multiprocessor
Introduction
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Introduction
• A Multiprocessor system is a system which is made up of multiple
processing units.
• Multiple microcontrollers (can be different models) may be used in a
system to fulfill requirements of the system at LOWER COST.
• The key to a multiprocessor system is communication between the
different microcontrollers.
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Multiprocessor
Serial Communication Protocols
Serial Communication
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Serial Communication Protocols
• Some common serial communication protocols
• RS 232
• RS 422 (a high-speed system similar to RS-232 but with differential signaling)
• RS 423 (a high-speed system similar to RS-422 but with referenced signaling)
• RS 485 (a descendant of RS-422 that can be used as a bus in multidrop
configurations)
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RS-232
• In telecommunications, RS-232 (Recommended Standard 232) is a
standard for serial binary single-ended data and control signals
connecting between a DTE (Data Terminal Equipment) and a DCE
(Data Circuit-terminating Equipment).
• Previously, it was commonly used in computer serial ports.
• The standard defines the electrical characteristics and timing of
signals, the meaning of signals, and the physical size and pin out of
connectors.
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Limitations of RS-232
• The large voltage swings and requirement for positive and negative supplies
• Increases power consumption
• Complicates power supply design
• Limits the upper speed of a compatible interface.
• Single-ended signaling referred to a common signal ground limits the noise
immunity and transmission distance.
• Multi-drop connection among more than two devices is not defined. While
multi-drop "workarounds" have been devised, they have limitations in speed and
compatibility.
• Asymmetrical definitions of the two ends of the link make the assignment of the
role of a newly developed device problematic; the designer must decide on either
a DTE-like or DCE-like interface and which connector pin assignments to use.
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Limitations of RS-232
• The handshaking and control lines of the interface are intended for
the setup and takedown of a dial-up communication circuit; in
particular, the use of handshake lines for flow control is not reliably
implemented in many devices.
• No method is specified for sending power to a device. While a small
amount of current can be extracted from the DTR and RTS lines, this
is only suitable for low power devices such as a mouse.
• The 25-way connector recommended in the standard is large
compared to current practice.
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RS-422
• RS-422 provides for data transmission, using balanced/differential
signaling, with unidirectional/non-reversible, terminated or
non-terminated transmission lines, point to point, or multi-drop.
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RS-422
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Standard EIA RS-422
Physical Media:
Network Topology:
Maximum Devices:
Maximum Distance:
Mode of Operation:
Maximum Baud Rate:
Voltage Levels:
Available Signals:
Connector types:
Twisted Pair
Point-to-point, Multi-dropped
10 (1 driver & 10 receivers)
1200 metres (4000 feet)
Differential
100Kbps - 10Mbps
-6V to +6V (maximum Voltage)
Mark(1) Negative Voltages
Space(0) Positive voltages
Tx+, Tx-, Rx+, Rx- (Full Duplex)
Not specified,
Commonly Screw terminals
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RS-423
• RS/EIA/TIA-423 is a standard for serial communications.
• It defines an unbalanced (single-ended) interface (similar to RS-232),
with a single, unidirectional sending driver, and allows for up to 10
receivers (similar to RS-422).
• It is normally implemented in integrated circuit technology and can
also be employed for the interchange of serial binary signals between
DTE & DCE.
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RS-423
• Standard EIA RS-423
• Physical Media:
Group of Copper cables
• Network Topology:
Point-to-point, Multi-dropped
• Maximum Devices:
10 (1 driver & 10 receivers)
• Maximum Distance: 1200 metres (4000 feet)
• Mode of Operation: Single Ended (Unbalanced)
• Maximum Baud Rate: Up to 100Kbps
• Voltage Levels:
-6V to +6V (maximum Voltage)
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Mark(1) -4V to -6V
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Space(0) +4V to +6V
• Available Signals: Tx, Rx & GND
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RS-485
• EIA-485, also known as TIA/EIA-485 or RS-485, is a standard defining
the electrical characteristics of drivers and receivers for use in
balanced digital multipoint systems.
• Digital communications networks implementing the EIA-485 standard
can be used effectively over long distances and in electrically noisy
environments.
• Multiple receivers may be connected to such a network in a linear,
multi-drop configuration.
• These characteristics make such networks useful in industrial
environments and similar applications.
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RS-485
Standard EIA RS-485
Physical Media:
Twisted Pair
Network Topology:
Point-to-point, Multi-dropped,
Multi-point Maximum Devices: 32 (32 drivers and 32 receivers)
Maximum Distance:
1200 metres (4000 feet)
Mode of Operation:
Differential
Maximum Baud Rate:
100 kbit/s - 10 Mbit/s
Voltage Levels:
-5 V to +5 V (max)
Mark(1) Positive Voltages (B-A > +200 mV)
Space(0) negative voltages (B-A < -200 mV)
Available Signals:
Tx+/Rx+, Tx-/Rx- (Half Duplex)
Tx+, Tx-, Rx+, Rx- (Full Duplex)
• Connector types:
Not specified.
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Connection Drivers
• For RS-422 and RS-485
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Connection Drivers
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Other Serial Protocols
• Inter-Integrated Circuit (I2C)
• Serial Peripheral Interface (SPI)
• Control Area Network (CAN)
• Ethernet
• Universal Serial Bus (USB)
• and many more…
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Multiprocessor
Master/Slave
Serial Communication
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Master/Slave
• Master/slave is a model of communication where one device or
process has unidirectional control over one or more other devices.
• In some systems a master is elected from a group of eligible devices,
with the other devices acting in the role of slaves.
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Master/Slave
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Multiprocessor
Network Configuration
Serial Communication
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Network Configuration
• Network topology is the arrangement of the various elements (links,
nodes, etc.) of a network system.
• Network configuration affects:
• Robustness of communication bus
• Cost
• Ease of fault isolation
• Access control
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Network Configuration
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Network Configuration
• Star:
• Reliability:
Single node lost per line lost
• Fault isolation:
Fault traceable to node and line
• Speed:
Each node has complete line used
• Ring/tree:
• Cost: Single line for all nodes, redundancy
• Bus/daisy chain
• Cost: Single line for all nodes, no redundancy
• Line
• Cost: Single line for all nodes, no redundancy
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Multiprocessor
Distributed System
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Distributed System
• A distributed system is a model in which components located on
networked processors communicate and coordinate their actions by
passing messages.
• The components interact with each other in order to achieve a
common goal.
• Three significant characteristics of distributed systems are:
• concurrency of components
• lack of a global clock
• independent failure of components.
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Distributed System
• Distributed systems may be preferable due to:
• Physical reasons: Components of the systems may be physically far away
from each other.
• Adding functions at lower cost.
• Design modularity: Different components may be developed and tested
independently and reused/upgraded in future designs.
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Distributed System
• With a distributed system, each processor may run in parallel/serial
with each other.
• Parallel: Each processor runs its process and updates information
to/from other processors. (e.g. LCD display in the lab)
• Serial: Each processor run depends on the information fed by
previous processor. (e.g. Sony PS3)
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Multiprocessor
Case Study
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Case Study 1
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Case Study 1
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Case Study 1
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Case Study 1
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Case Study 2
Robot Tracking Camera
Large Gas Sensor Array
(LGSA)
Gas sensor
Robot
Robot Arena
Base Station
PC
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Case Study 2
I2C Bus
TX
SB1
SB3
SB2
SB4
TX - WSN transmitter
SBn - Sensor board
Sn – Gas sensor
S1
S2
S3
S4
S5
S6
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Case Study 2
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Case Study 2
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Case Study 3
• World Community Grid enables anyone with a computer,
smartphone or tablet to donate their unused computing power to
advance cutting-edge scientific research on topics related to health,
poverty and sustainability.
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Case Study 3
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Case study 4
• Multi-core microcontrollers
• Infeneon Technologies AG
• Aurix Microcontroller Family
• Parallax Incorporated
• P8X32A Propeller Microcontroller Family
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Case Study 4
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Case Study 4
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Multiprocessor
Summary
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Summary
• Microcontrollers are everywhere; and with new technologies, are
even more connected with one another.
• Engineers must be able to design systems which are low cost, easy to
maintain, and fulfills the application needs.
• Using multiple microcontrollers in a system can simplify development
and testing process, reduce cost, increase portability, produce
reusable and reliable system.
• New & exciting technology awaits you..
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