In automotive electronics networking, the commonly networking standard used is called CAN or controller area network which uses a baud rate of up to 1Mbps. This speed is needed in the control of engine and other critical components of the automobile that requires fast transfer of information. However, there are some areas of control which does not require that kind of speed and hence a slower speed standard can be utilised to save control cost. Some of these areas are the mirrors control, Window lift, seat control and door lock amongst others.
Due to this requirements, a consortium was formed in 1998 consisting of 5 automotive manufacturers (Volvo, BMW, Audi, VW and Daimler-Chrysler), 1 tool supplier (VCT) and 1 semiconductor supplier (Motorola) to look into this. As a result, the LIN (Local Interconnect Network) specifications was finalised on 2 February 2000. The first version of LIN was 1.1 and currently version 2.0 is in use. The most recent development
in LIN is the use of it over the vehicle's battery line using a DC-LIN transceiver. Some of the main features of LIN are listed below.
* One master and up to 16 slaves. No collision detection feature is needed as master initiated all messages communication with slaves. The master is usually implemented with a more powerful microcontroller compared to the slaves as it has to handle more tasks.
* Baudrate of up to 20kbps. Slower speed is chosen to reduce the effect of electromagnetic interference.
* Single wire implementation based on enhanced ISO 9141.
* Simple SCI or UART hardware interface which is available in most microcontroller chips making its implementation cost effective.
* Self synchronization in the slave nodes without the need to have crystal or ceramic resonator. Internal RC oscillator for the microcontroller is good enough and hence making its implementation lower cost.
Monday, August 17, 2009
Zigbee - Emerging Simple Wireless System
Introduction To Zigbee
In the wireless world, the name Bluetooth
and WIFI have become a household name in recent years. They quickly find applications amongst others in mobile computing and mobile phones.
Zigbee is the result of the demand from industry and consumer for wireless applications that demand for lower data rate, longer battery life, simple design, shorter range and low cost solutions.
Introduction To IEEE 802.15.4
IEEE 802.15.4 is a simple standard that specifies the Media Access Controller (MAC) and Physical (PHY) networking layers for packet data protocol. Its license free frequency bands are:
2.4 GHz (16 channels with baud rate of 250 kps)
902 MHz - 928 MHz (10 channels with baud rate of 40 kps)
868 MHz - 870 MHz (1 channel with baud rate of 20 kps)
North America, Europe, Australia and New Zealand use the sub 1 GHz bands whereas the rest of the world uses 2.4 GHz bands.
It uses Carrier Sense Multiple Access with Collison Avoidance for Channel Access.
The security method used is AES-128.
Has message acknowledgement and a host of other features.
Zigbee Applications
Zigbee technology is based on IEEE 802.15.4 industry standard. It incorporates the standard, adding the logical network, security and software to it. It supports up to 3 network topologies namely STAR, MESH and CLUSTER tree. Developers need only have to focus on application while the MCU/Microprocessor/RF Transceiver makers and Zigbee Alliance take care of the RF Transmitter, RF Receiver, RF Channel and its protocol.
There are 3 types of traffics that can be used.
a) Periodic data
An example of this traffic is a wireless sensor to read the water meter. The sensor is programmed to wake up at certain interval to transmit the information needed and goes back to sleep after this is done.
b) Intermittent data
An example of this traffic is a wireless light switch to ON or OFF a light manually. It is triggered only by external input and hence wakes up to transmit the message to the network. When done, it is disconnected to the network and hence save energy.
c) Repetitive data
An example of this traffic is the security system monitoring. The devices are time multiplex to return its status to the network. This type uses more energy.
There are numerous applications that can be implemented using Zigbee. Amongst others are in the industry and home applications.
In the industry, the applications include utility and metering where gas/water/electricity meter readings are automated and send back to utility headquarter for further action. This saves the time it takes for their personnel to come to the premises to take its reading. In the area of warehousing/inventory management , the wireless technology will enable accurate and hassle free management of goods. Security and access control, building management system and lighting control are among the applications that can be implemented with ease.
In the home, a total home automation system to control lightings, blinds, air conditioning, security system, remote control and appliances can be implemented.
In the wireless world, the name Bluetooth
and WIFI have become a household name in recent years. They quickly find applications amongst others in mobile computing and mobile phones.
Zigbee is the result of the demand from industry and consumer for wireless applications that demand for lower data rate, longer battery life, simple design, shorter range and low cost solutions.
Introduction To IEEE 802.15.4
IEEE 802.15.4 is a simple standard that specifies the Media Access Controller (MAC) and Physical (PHY) networking layers for packet data protocol. Its license free frequency bands are:
2.4 GHz (16 channels with baud rate of 250 kps)
902 MHz - 928 MHz (10 channels with baud rate of 40 kps)
868 MHz - 870 MHz (1 channel with baud rate of 20 kps)
North America, Europe, Australia and New Zealand use the sub 1 GHz bands whereas the rest of the world uses 2.4 GHz bands.
It uses Carrier Sense Multiple Access with Collison Avoidance for Channel Access.
The security method used is AES-128.
Has message acknowledgement and a host of other features.
Zigbee Applications
Zigbee technology is based on IEEE 802.15.4 industry standard. It incorporates the standard, adding the logical network, security and software to it. It supports up to 3 network topologies namely STAR, MESH and CLUSTER tree. Developers need only have to focus on application while the MCU/Microprocessor/RF Transceiver makers and Zigbee Alliance take care of the RF Transmitter, RF Receiver, RF Channel and its protocol.
There are 3 types of traffics that can be used.
a) Periodic data
An example of this traffic is a wireless sensor to read the water meter. The sensor is programmed to wake up at certain interval to transmit the information needed and goes back to sleep after this is done.
b) Intermittent data
An example of this traffic is a wireless light switch to ON or OFF a light manually. It is triggered only by external input and hence wakes up to transmit the message to the network. When done, it is disconnected to the network and hence save energy.
c) Repetitive data
An example of this traffic is the security system monitoring. The devices are time multiplex to return its status to the network. This type uses more energy.
There are numerous applications that can be implemented using Zigbee. Amongst others are in the industry and home applications.
In the industry, the applications include utility and metering where gas/water/electricity meter readings are automated and send back to utility headquarter for further action. This saves the time it takes for their personnel to come to the premises to take its reading. In the area of warehousing/inventory management , the wireless technology will enable accurate and hassle free management of goods. Security and access control, building management system and lighting control are among the applications that can be implemented with ease.
In the home, a total home automation system to control lightings, blinds, air conditioning, security system, remote control and appliances can be implemented.
Home Lighting System Project
Introduction To Home Lighting System
In recent year, the control of Home Lighting System
has developed from standalone type to more complicated networking controls. Many building management system
and even the security system have incorporate the control of lighting into their system as a total solution to their customers. However, there are still no single universal protocol for the building or lighting control system.
The lighting industry has developed a new standard for communication with electronic ballast. Electronic ballast is a common lighting device that is used in practically every building, factory or residential house. This standard called IEC 929 is an interface standard for communication between a controller and the electronic ballast. The standard for the control is called DALI, an acronym for Digital Addressable Lighting Interface. DALI is meant for home or industry use which has 2 wire communication connection between the master-slave and slave-slave. It is developed to reduce the cost of implementation.
Among the features that can be applied are dimming features and control for different grouping/section of the building.
The electronic ballasts can have up to 16 groups and each group can have up to 16 different lighting parameters for the lighting scenes. Each controller can controlled up to 64 electronic ballasts.
There are many ways to implement the DALI depending on the cost and requirements of a home or building. Most of the time, a microcontroller is used at both the slave and the master controller units as this is one of the most cost effective ways to implement the system.
In recent year, the control of Home Lighting System
has developed from standalone type to more complicated networking controls. Many building management system
and even the security system have incorporate the control of lighting into their system as a total solution to their customers. However, there are still no single universal protocol for the building or lighting control system.
The lighting industry has developed a new standard for communication with electronic ballast. Electronic ballast is a common lighting device that is used in practically every building, factory or residential house. This standard called IEC 929 is an interface standard for communication between a controller and the electronic ballast. The standard for the control is called DALI, an acronym for Digital Addressable Lighting Interface. DALI is meant for home or industry use which has 2 wire communication connection between the master-slave and slave-slave. It is developed to reduce the cost of implementation.
Among the features that can be applied are dimming features and control for different grouping/section of the building.
The electronic ballasts can have up to 16 groups and each group can have up to 16 different lighting parameters for the lighting scenes. Each controller can controlled up to 64 electronic ballasts.
There are many ways to implement the DALI depending on the cost and requirements of a home or building. Most of the time, a microcontroller is used at both the slave and the master controller units as this is one of the most cost effective ways to implement the system.
Sensorless BLDC Motor Power Inverter Circuit Design Project
Introduction To Power Inverter Circuit Design
Power electronics motor control have evolved from simple ON/OFF control to more complex electronic control circuitry in recent years. In the area of consumer electronics, the products that have been impacted by inverter based technology are air conditioners and washing machines and refrigerator.
The inverter technology development has been moving at a fast pace in the quest for more efficient and environmental friendly products. Energy savings have been the key drivers as our the oil and gas resources of our earth is fast depleting. The inverter development started from AC inverter control which evolved to DC inverter control and recently sensorless brushless DC motor control. The sensorless BLDC motor inverter control has more complex circuitry but is far more efficient and long lasting compared to AC inverter control.
Brushless DC Vs Sensorless Brushless DC Control
In BLDC control, a few Hall sensors are placed on the stator of the motor to detect the position of the rotor during the operation of the motor. The sensors are normally build into the printed circuit board and mounted onto the enclosure cap of the non driving end of the motor. The setback of this method is that the sensors and PCB need to be placed in a location where the temperature of the motor will not build up and thus affect the lifetime and operation of the PCB.
In Sensorless BLDC control, there is no need to have any Hall sensors to sense the position of the rotor. The sensing of the rotor position is by the analysis of the back electromotive force that is generated at the stator of the motor windings. By using this method, the reliability of the control system is enhanced. The setback of this method is that the algorithm and control circuit to detect the back EMF is complex, hence requiring more powerful microcontroller and software knowledge.
Power Inverter Circuit Design Application
A good sensorless BLDC motor Power Inverter Circuit Design Application Notes and its source codes can be downloaded from Microchip website. The control circuitry functions include the sensing of Back EMF, the driving of DC Motor using IGBTs, detection of overcurrent and RS 232 communications interface.
Power electronics motor control have evolved from simple ON/OFF control to more complex electronic control circuitry in recent years. In the area of consumer electronics, the products that have been impacted by inverter based technology are air conditioners and washing machines and refrigerator.
The inverter technology development has been moving at a fast pace in the quest for more efficient and environmental friendly products. Energy savings have been the key drivers as our the oil and gas resources of our earth is fast depleting. The inverter development started from AC inverter control which evolved to DC inverter control and recently sensorless brushless DC motor control. The sensorless BLDC motor inverter control has more complex circuitry but is far more efficient and long lasting compared to AC inverter control.
Brushless DC Vs Sensorless Brushless DC Control
In BLDC control, a few Hall sensors are placed on the stator of the motor to detect the position of the rotor during the operation of the motor. The sensors are normally build into the printed circuit board and mounted onto the enclosure cap of the non driving end of the motor. The setback of this method is that the sensors and PCB need to be placed in a location where the temperature of the motor will not build up and thus affect the lifetime and operation of the PCB.
In Sensorless BLDC control, there is no need to have any Hall sensors to sense the position of the rotor. The sensing of the rotor position is by the analysis of the back electromotive force that is generated at the stator of the motor windings. By using this method, the reliability of the control system is enhanced. The setback of this method is that the algorithm and control circuit to detect the back EMF is complex, hence requiring more powerful microcontroller and software knowledge.
Power Inverter Circuit Design Application
A good sensorless BLDC motor Power Inverter Circuit Design Application Notes and its source codes can be downloaded from Microchip website. The control circuitry functions include the sensing of Back EMF, the driving of DC Motor using IGBTs, detection of overcurrent and RS 232 communications interface.
Subscribe to:
Posts (Atom)
