International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue4- April 2013
Motor Speed Control Based On Temperature Using
Can Protocol
CH.Mounika#1, K.S.Roy #2, Mahaboob Ali *3
#
Dept. of ECE, K.L.University
Guntur, India
* Vyas Informatics
Hyderabad, India
Abstract -- . This paper describes how to control the DC motor
based on the parameters like temperature changes using CAN
protocol implementation. This Paper deals with the Control of DC
Motor based upon the temperature changes that occur in a
process in Industry. The LM35 series are precision integratedcircuit temperature sensors, whose output voltage is directly
proportional to the Celsius (Centigrade) temperature. The
Temperature changes are measured by the ADC and transmitted
to the other node using the CAN Bus and the data is received at
the other node based upon the data received the speed of the DC
motor is Regulated using the PWM (pulse width Modulation)
Technique. This PWM is achieved by on Chip Timers. The motor
is connected to a cooling device to control the temperature.
I.INTRODUCTION
Controller–area network (CAN or CANbus) is a vehicle bus standard designed to allow
microcontrollers and devices to communicate with each other
within a vehicle without a host computer.CAN is a messagebased protocol, designed for various applications like
automotive applications ,industrial automation and medical
equipment . This paper describes the design of a system that
shows the operation of several subsystems emulating
automotive and industrial applications across the CAN bus.
The Controller Area Network (CAN) is a Serial,
Asynchronous, Multi-master communication protocol for
connecting electronic control modules in Automobile and
industrial applications. CAN have many features like Less cost,
Ease of implementation, point to point Networking with powerful
Error Checking and with High Transmission Rate of
1MBitps.The CAN Network is a Peer to Peer Network consisting
of different nodes. Different parameters can be monitored by
these Nodes and can be updated to the Central Control Unit.
Mostly used in Industry and Auto Mobiles and it is reliable.
II.BLOCK DIAGRAM
Current automobiles may have as many as fifty
electronic control units (ECU) for various subsystems. Typically
the biggest processor is the engine control unit in the automobiles;
others are used for transmission, airbags, antilock braking, audio
devices, windows, mirror adjustment, etc. Some of these form
independent subsystems, but communications among others are
essential. Subsystems need to control actuators or receive
feedback from sensors. Thus to fulfill the above needs CAN
standard was used.
The CAN bus is used in vehicles to connect engine
control unit and transmission, or (on a different bus) to connect
the door locks, temperature control, seat adjustments etc.
Key words-- CAN,PIC, C Compiler
ISSN: 2231-5381
http://www.ijettjournal.org
Page 1249
International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue4- April 2013
The temperature sensor lm35 measures the temperature at the
industries and send the analog values to the PIC controller.
An Ignition switch is a switch in the control system of an
internal combustion engined vehicle that activates the main
electrical systems for the vehicle. Besides providing power to
the ignition system components it also usually switches on
power to many "accessories" (radio, power windows, etc.).
A proximity sensor is a sensor able to detect the presence of
nearby objects without any physical contact. The proximity
sensor emits a beam of electromagnetic radiation (infrared,
for instance), and looks for changes in the field or return signal.
The analog outputs of the sensors are digitized in the PIC
controller and based upon the programming in the controller ,
control measures are to be taken by using the can controller by
driving the motors. Here the programming is done using
embedded C.
.
III.DESCRIPTION
B. Node Requirements
The host processor decides what received messages mean and
which messages it wants to transmit itself. Sensors, actuators
and control devices can be connected to the host processor.
C. CAN controller (hardware with a synchronous clock).
1) Receving: The CAN controller stores received bits serially
from the bus until an entire message is available, which can
then be fetched by the host processor (usually after the CAN
controller has triggered an interrupt).
2) Sending: The host processor stores it’s transmit messages to
a CAN controller that transmits the bits serially through the
bus.
Bus state with two nodes transmitting
A.CAN Bus Overview
The Controller Area Network (CAN) bus is a multi-master
message broadcast system that is used in various systems
where data is in the form of short messages are needed to be
received at multiple locations parallely. As messages are sent
to all the nodes in a system, CAN is especially used in systems
where consistency in the received messages at all the receiving
nodes is needed. Provisions are included in the protocol to
reject messages if any destination node identifies an error. In
such a case, all nodes are notified of the rejection, ensuring the
data consistency across the network. Messages are sent to all
nodes, but the message identifier indicate whether each node
should act on the message. However, every node participate in
indicating whether the message was sent correctly or not, and
thus increasing the reliability of the bus. CAN is a multi-master
broadcast serial bus standard for connecting electronic control
units (ECUs).Each node is able to send and receive messages,
but not at same time. The message consists primarily of an id,
which represents the priority of the message, and 8 data bytes.
It is transmitted serially to the bus. The signal pattern is
encoded in non-return-to-zero(NRZ) waveform and is sensed
by all nodes. The modules that are connected through CAN
network are typically sensors, actuators, and other control
devices. These devices are not connected directly to the bus,
but through a host processor and a CAN controller so that if the
bus is free, any node may begin to transmit. If two or more
nodes begin sending messages simultaneously, the message
with the more dominant id will overwrite other nodes' less
dominant id's, so that eventually only the dominant message
remains and is received by all nodes. This method is referred to
as priority based bus arbitration. Messages with id of
ISSN: 2231-5381
numerically smaller values have higher priority and are
transmitted first.
Truth table for dominant/recessive
.D. Data Transmission
A CAN message that is transmitted with highest priority will
succeed and the node that is transmitting the comparatively
lower priority message will sense this and wait. This is
achieved by CAN transmitting data through a binary model of
"dominant" bits and "recessive" bits where dominant is a
logical 0 and recessive is a logical 1. If one node transmits a
dominant bit and another node transmits a recessive bit then the
dominant bit "wins" (a logical AND between the two).
Logical AND
Truth table for logical AND
A dominant bit is asserted by creating a voltage across the
wires while a recessive bit is simply not asserted on the bus. If
http://www.ijettjournal.org
Page 1250
International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue4- April 2013
any node sets a voltage difference, all nodes get updated about
it. Thus there is no delay to the higher priority messages.
When used with a differential bus, a carrier sense multiple
access/bitwise arbitration scheme (CSMA/BA)
is
implemented: if two or more devices start transmitting at the
same time, there is a priority based arbitration scheme to
decide which one will be granted permission to continue
transmitting. The CAN solution to this is prioritized arbitration
(and for the dominant message delay free), making CAN very
suitable for real time prioritized communications systems.
During arbitration, each transmitting node monitors the bus
state and compares the received bit with the transmitted bit. If a
dominant bit is received when a recessive bit is transmitted
then the node stops transmitting (i.e., it lost arbitration).
Arbitration is performed during the transmission of the
identifier field. Every node starting to transmit at the same time
sends an id. With dominant as binary value 0, starting from the
high bit.If their id. is a larger number (lower priority) they will
be sending 1 (recessive) and see 0 (dominant), so they back off.
At the end of id. transmission, all nodes but one have backed
off, and the highest priority message gets through unimpeded.
IV. WORKING
Embedded networking is currently the hottest
topic in the embedded systems. Can is a technology designed
for embedded networking in highly disturbed environments,
like industries and automobiles. It is a powerful yet costeffective solution for connecting various embedded devices.
This technology requires only two wires to connect between
two different nodes.
ISSN: 2231-5381
Fig : Controlling of different ECUs in car using CAN controller
This paper aims to implement a vehicle automation system to
control the engine and body electronics of a car and also in the
industries to control the temperature of heavy load machines by
using coolants like air conditioners. This system will also be
able to check and take remedial actions in case of failure of the
accessories that are controlled by it. These nodes are made up
of a can controller, a microcontroller and a can transceiver. The
can nodes are connected to variable sensors for data collection
and these data is transmitted through the can network to other
nodes for processing. Among these nodes one is considered as
server node and this node sends and receives commands and
signals to and from other nodes and initiates necessary actions.
This node is connected to an lcd display, which is used to
display the menu and the actions being initiated by the server.
A keypad is also connected to the server node to facilitate input
of commands. The server node controls the engine electronics
and body electronics of the car. Here we use the server to
control the body electronics that is Head lights, seat belts, door
lock, a/c etc.
Sub node 1: This node is used to control the a/c and for
checking door locks. This node monitors the door locks and
sends signals to server to issue warnings when the door locks
are not locked. This sub node also monitors the current
temperature and operate the a/c to the desired temperature set
by the user. The temperature is measured by a temperature
sensor lm35, whose output voltage is linearly proportional to
the celsius temperature.
Sub node 2: This node is used for seat belt and head light
control. Here we will be using light sensor (ldr) which
monitors the light infront of the car and take decision according
to intensity of light (dim/bright the head light). Here the ldr
measured values is in the range of 0-1023.If the ldr measured
value is 0,the head lights will automatically on, or else if the ldr
measured value is 1023,the headlights of the car will
automatically off. This node also monitors the seat belts and
sends signals to server to issue warnings when the seat belts are
not locked. A photoresistor is an electronic component whose
resistance decreases with increasing incident light intensity. It
can also be called a light-dependent resistor (ldr), or
photoconductor. A photoresistor is made of a high-resistance
semiconductor. If light falling on the device is of high enough
frequency, photons absorbed by the semiconductor give bound
electrons enough energy to jump into the conduction band. The
resulting free electron (and its hole partner) conduct electricity,
thereby lowering resistance. In the industrial applications the
temperature of the machines are controlled by the lm35
http://www.ijettjournal.org
Page 1251
International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue4- April 2013
sensors.If the
temperature is maintained above 40c
,automatically coolants will be on.
[10]. “CANBus Networks Break into Mainstream Use,” EDN, Aug. 22, 2002,
V. ADVANTAGES





[9]. Texas Instruments, “Introduction to the Controller Area Network (CAN),”
Application Report SLOA101, August 2002.
pp.53-60 by D. Marsh.
Easy to implement and extend.
Well-suited for temporary or small networks not requiring
high speeds (quick setup) resulting in faster networks.
Less expensive than other topologies (But in recent years
has become less important due to devices like a switch)
Cost effective; only a single cable is used.
Easy identification of cable faults. The breakdown of a
CAN station has no immediate impact on the CAN bus.
All the other stations can communicate unconstrained.
VI. CONCLUSION
In this project we have implemented industrial parameter
control through CAN protocol by using PIC microcontroller.
By using CAN protocol a vehicle bus standard designed to
allow microcontroller and devices to communicate with each
other with in a vehicle without a host computer. The sensors,
actuators and other control devices that are connected by CAN
protocol.
ACKNOWLEDGMENT:
I am thankful to Mr. K Sripath Roy and Mr.
Mahaboob Ali for their guidance in preparing this paper.
REFERENCES
[1]. The New old Economy: oil, Computers And The Reinvention of the Earth,
The atlantic by J.Rauch (2001).
[2]. Hybrid control systems, UNESCO Encyclopedia of life support systems.
Dept of signals, sensors & Systems, RoYal institute of technology, Sweden by
K.H.Johansson (2002).
[3]. Lecture notes on hybrid systems. Dept of Elect. Comp. Engg. University of
Patras, Greece by J. Lygeros (2004).
[4]. The 8051Micro controllers and embedded systems by A.K.Ray and Mazidi
(2000).
[5]. Design with PIC Micro controllers, Pearson education by John B peatman
(1998).
[6]. Embedded Micro controllers. Pearson Education by Todd D Morton
(2001).
[7]. Industrial Automation using CAN Bus Platform White Paper,TEXAS
INSTRUMENTS
[8]. Research Article ON CAN PROTOCOL IMPLEMENTATION FOR
INDUSTRIAL PROCESS
ISSN: 2231-5381
http://www.ijettjournal.org
Page 1252