29-05-2012, 10:15 AM
Bluetooth based home automation system
[attachment=23272]
Abstract
The past decade has seen significant advancement in the field of consumer electronics. Various ‘intelligent’ appliances such as cellular
phones, air-conditioners, home security devices, home theatres, etc. are set to realize the concept of a smart home. They have given rise to a
Personal Area Network in home environment, where all these appliances can be interconnected and monitored using a single controller. Busy
families and individuals with physical limitation represent an attractive market for home automation and networking. A wireless home
network that does not incur additional costs of wiring would be desirable. Bluetooth technology, which has emerged in late 1990s, is an ideal
solution for this purpose. This paper describes an application of Bluetooth technology in home automation and networking environment. It
proposes a network, which contains a remote, mobile host controller and several client modules (home appliances). The client modules
communicate with the host controller through Bluetooth devices. q 2002 Elsevier Science B.V. All rights reserved.
Keywords: Bluetooth technology; Microcontroller; Home automation; Wireless network
1. Introduction
The Bluetooth wireless technology is set to revolutionize
the way people perceive digital devices in our homes and
office environment. Now they are no longer just the
individual devices; instead, with the embedded Bluetooth
technology, they form a network in which appliances can
communicate with each other. This wireless technology is
especially useful in home environment, where there exists
hardly any infrastructure to interconnect intelligent appliances.
It could be suitably used for home automation in a
cost-effective manner. Operating over unlicensed, universally
available frequency of 2.4 GHz, it can link digital
devices within a range of 10 m (expandable to 100 m, by
increasing the transmitted power) at the speed of 1 Mbps.
Building upon this theme; we propose a home automation
system based on Bluetooth technology [1,2].
There are certain issues involved in the design of a home
automation system. The system should be scalable, so that
new device can easily be integrated into it. It should provide
a user-friendly interface on the host side, so that the devices
can be setup, monitored and controlled. The interface should
also provide some diagnostic services so those problems
with the system, if any, can be tracked down. The overall
system should be fast enough to realize the true power of
wireless technology. It should also be cost effective in order
to justify its application in home automation.
The system developed during the course of this research
consists of a Host Controller (HC) implemented on a
Personal Computer (PC), and a microcontroller based
temperature-sensor/fan-controller, that is able to communicate
with the host through the Bluetooth link. The system
is based on Home Automation Protocol (HAP), developed
by the authors in order to facilitate the master–slave
communication in a home automation network [3]. This
protocol ensures a prioritized, interlocked exchange of data.
It also supports dynamic addition and removal of devices on
the network. A user interface on the PC offers device
registration, control as well as diagnostic utilities. Bluetooth
development kit from Ericsson was used for the development
[4]. A microcontroller was used as a device controller
for client modules [5,6].
The paper has been structured as follows. Section 2 of
this paper explains the HAP. Section 3 describes the salient
features of the user interface and PC to Bluetooth interface
for the host system. In Section 4, we present the temperature
sensor–fan controller circuitry and its interface to the
microcontroller through I2C lines. Section 5 discusses the
microcontroller to Bluetooth interface and the development
of a firmware for the microcontroller. Finally some
0141-933/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved.
PII: S0 14 1 -9 33 1 (0 2) 00 0 39 -X
Microprocessors and Microsystems 26 (2002) 281–289
www.elsevierlocate/micpro
* Corresponding author.
E-mail addresses: esris[at]ntu.edu.sg (N. Sriskanthan), assltan[at]ntu.edu.
sg (F. Tan), advait[at]pmail.ntu.edu.sg (A. Karande).
recommendations regarding further research in this area are
discussed.
2. Home Automation Protocol
The Home Automation Protocol (HAP) facilitates the
communication among the host and client modules in a
home automation system. The communication covers the
device initialization process and the data transaction
process.
The protocol is constructed above Bluetooth software
stack [7]. It follows the layer model proposed by Bluetooth
Special Interest group (SIG). Considering the requirements
of home automation environment, the HAP has been based
on the core of the Bluetooth protocol architecture that
comprises of three stacks:
† Logical Link Control and Adaptation Protocol (L2CAP)
† Service Discovery Protocol (SDP)
† RFCOMM (serial cable emulation protocol) protocol.
HAP device initialization process uses the enhanced SDP
functionality to query device information and services.
L2CAP provides data services to the HAP with protocol
multiplexing capability, segmentation and reassembly operations.
RFCOMM facilitates wireless communication and
provides transport capabilities for home automation services.
A typical Bluetooth based home automation system
includes a host and several client modules. Considering the
entrance price of the Bluetooth, it will be more cost effective
to have multiple Device Controllers (DC) connected to a
Bluetooth device. Each DC, in turn, monitors multiple
Attached Devices (AD) as shown in Fig. 1.
2.1. Home automation descriptor table
The host needs to store information regarding all the
active devices in the network. Similarly a DC needs to store
information pertaining to the devices directly attached to it.
The information is stored in the form of descriptors. The
formats of descriptors on the DC and the host are shown in
Tables 1 and 2, respectively.
Descriptor table terms explanation:
AD the ID of the attached device
TOD the type of Attached Device (I2C address)
I_SIZE the instruction size in bytes for given device
D_SIZE the data size in bytes for given device
D_NAME the device name, a NULL terminated string (32
bytes)
RW the read and write access: Read Only ($00),
Write Only ($01), Read & Write ($02)
Fig. 1. Bluetooth based home automation system. (a) Host and client modules in a Bluetooth piconet. (b) An individual client module.
282 N. Sriskanthan et al. / Microprocessors and Microsystems 26 (2002) 281–289
PRIORITY the priority between the various ADs
STATUS there are three states for devices: Pending
($00), ACK ($01), NACK ($02)
2.2. Protocol description
Fig. 2 shows the process diagram for HAP. The four
indexed activities in the diagram are as follows:
(1) DC searches for all existing ADs and places them in the
DC descriptor table.
(2) HC searches for device information in DC database
and constructs the descriptor table.
(3) HC periodically checks the status of each DC and
requests it to check its devices.
(4) DC searches for all the devices and sends back the
feedback information. If new device is found, DC
sends the Device Detection Packet (DDP). If a device
is not found (removed), the DC sends the Device
Removal Packet (DRP).
The sequence of operations can be categorized into three
different processes as follows.
2.2.1. Device initialization process
1. On reset, the HC sends Device Checking Packet (DCP) to
each DC. A DC performs a scan on its ADs and sends a
DDP to the host for each device found.
2. If the AD information is found on the HC, it will
automatically pop up the window for device control. If
user acknowledges the device found, an ACKP would be
sent back to the DC, otherwise NACKP would be sent.
3. If the new AD is not stored in the HC, HC will pop up
window to request user to configure the new AD. If user
acknowledges and configures the device, the ACKP
would be sent back to the DC, otherwise NACKP would
be sent.
2.2.2. Periodic checking process
1. Host periodically sends the DCP to a DC to check if it is
working properly and whether any new AD has been
added or removed. If HC does not receive an acknowledgment
from the DC, the host assumes that the DC is
not working properly or has been removed. The HC will
stop transferring any information to the AD of that DC.
2. When a DC finds a new AD or a removed AD while
performing a DCP, it sends DDP or DRP to the HC.
Depending on whether the HC acknowledges it or not,
the DC updates the local descriptor table.
2.2.3. Data transaction process
1. CMDP (Command packet) will be sent from the HC to a
DC in order to control the AD or to retrieve status
information of the AD.
2. If the packet received by the DC is to control an AD and
no data is required in return, an ACKP will be sent back
to the HC, after executing the necessary commands.
3. If the command packet requests for data, a DATAP (Data
packet) will be sent back to HC.
All packet formats are described in Section 2.3.
[attachment=23272]
Abstract
The past decade has seen significant advancement in the field of consumer electronics. Various ‘intelligent’ appliances such as cellular
phones, air-conditioners, home security devices, home theatres, etc. are set to realize the concept of a smart home. They have given rise to a
Personal Area Network in home environment, where all these appliances can be interconnected and monitored using a single controller. Busy
families and individuals with physical limitation represent an attractive market for home automation and networking. A wireless home
network that does not incur additional costs of wiring would be desirable. Bluetooth technology, which has emerged in late 1990s, is an ideal
solution for this purpose. This paper describes an application of Bluetooth technology in home automation and networking environment. It
proposes a network, which contains a remote, mobile host controller and several client modules (home appliances). The client modules
communicate with the host controller through Bluetooth devices. q 2002 Elsevier Science B.V. All rights reserved.
Keywords: Bluetooth technology; Microcontroller; Home automation; Wireless network
1. Introduction
The Bluetooth wireless technology is set to revolutionize
the way people perceive digital devices in our homes and
office environment. Now they are no longer just the
individual devices; instead, with the embedded Bluetooth
technology, they form a network in which appliances can
communicate with each other. This wireless technology is
especially useful in home environment, where there exists
hardly any infrastructure to interconnect intelligent appliances.
It could be suitably used for home automation in a
cost-effective manner. Operating over unlicensed, universally
available frequency of 2.4 GHz, it can link digital
devices within a range of 10 m (expandable to 100 m, by
increasing the transmitted power) at the speed of 1 Mbps.
Building upon this theme; we propose a home automation
system based on Bluetooth technology [1,2].
There are certain issues involved in the design of a home
automation system. The system should be scalable, so that
new device can easily be integrated into it. It should provide
a user-friendly interface on the host side, so that the devices
can be setup, monitored and controlled. The interface should
also provide some diagnostic services so those problems
with the system, if any, can be tracked down. The overall
system should be fast enough to realize the true power of
wireless technology. It should also be cost effective in order
to justify its application in home automation.
The system developed during the course of this research
consists of a Host Controller (HC) implemented on a
Personal Computer (PC), and a microcontroller based
temperature-sensor/fan-controller, that is able to communicate
with the host through the Bluetooth link. The system
is based on Home Automation Protocol (HAP), developed
by the authors in order to facilitate the master–slave
communication in a home automation network [3]. This
protocol ensures a prioritized, interlocked exchange of data.
It also supports dynamic addition and removal of devices on
the network. A user interface on the PC offers device
registration, control as well as diagnostic utilities. Bluetooth
development kit from Ericsson was used for the development
[4]. A microcontroller was used as a device controller
for client modules [5,6].
The paper has been structured as follows. Section 2 of
this paper explains the HAP. Section 3 describes the salient
features of the user interface and PC to Bluetooth interface
for the host system. In Section 4, we present the temperature
sensor–fan controller circuitry and its interface to the
microcontroller through I2C lines. Section 5 discusses the
microcontroller to Bluetooth interface and the development
of a firmware for the microcontroller. Finally some
0141-933/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved.
PII: S0 14 1 -9 33 1 (0 2) 00 0 39 -X
Microprocessors and Microsystems 26 (2002) 281–289
www.elsevierlocate/micpro
* Corresponding author.
E-mail addresses: esris[at]ntu.edu.sg (N. Sriskanthan), assltan[at]ntu.edu.
sg (F. Tan), advait[at]pmail.ntu.edu.sg (A. Karande).
recommendations regarding further research in this area are
discussed.
2. Home Automation Protocol
The Home Automation Protocol (HAP) facilitates the
communication among the host and client modules in a
home automation system. The communication covers the
device initialization process and the data transaction
process.
The protocol is constructed above Bluetooth software
stack [7]. It follows the layer model proposed by Bluetooth
Special Interest group (SIG). Considering the requirements
of home automation environment, the HAP has been based
on the core of the Bluetooth protocol architecture that
comprises of three stacks:
† Logical Link Control and Adaptation Protocol (L2CAP)
† Service Discovery Protocol (SDP)
† RFCOMM (serial cable emulation protocol) protocol.
HAP device initialization process uses the enhanced SDP
functionality to query device information and services.
L2CAP provides data services to the HAP with protocol
multiplexing capability, segmentation and reassembly operations.
RFCOMM facilitates wireless communication and
provides transport capabilities for home automation services.
A typical Bluetooth based home automation system
includes a host and several client modules. Considering the
entrance price of the Bluetooth, it will be more cost effective
to have multiple Device Controllers (DC) connected to a
Bluetooth device. Each DC, in turn, monitors multiple
Attached Devices (AD) as shown in Fig. 1.
2.1. Home automation descriptor table
The host needs to store information regarding all the
active devices in the network. Similarly a DC needs to store
information pertaining to the devices directly attached to it.
The information is stored in the form of descriptors. The
formats of descriptors on the DC and the host are shown in
Tables 1 and 2, respectively.
Descriptor table terms explanation:
AD the ID of the attached device
TOD the type of Attached Device (I2C address)
I_SIZE the instruction size in bytes for given device
D_SIZE the data size in bytes for given device
D_NAME the device name, a NULL terminated string (32
bytes)
RW the read and write access: Read Only ($00),
Write Only ($01), Read & Write ($02)
Fig. 1. Bluetooth based home automation system. (a) Host and client modules in a Bluetooth piconet. (b) An individual client module.
282 N. Sriskanthan et al. / Microprocessors and Microsystems 26 (2002) 281–289
PRIORITY the priority between the various ADs
STATUS there are three states for devices: Pending
($00), ACK ($01), NACK ($02)
2.2. Protocol description
Fig. 2 shows the process diagram for HAP. The four
indexed activities in the diagram are as follows:
(1) DC searches for all existing ADs and places them in the
DC descriptor table.
(2) HC searches for device information in DC database
and constructs the descriptor table.
(3) HC periodically checks the status of each DC and
requests it to check its devices.
(4) DC searches for all the devices and sends back the
feedback information. If new device is found, DC
sends the Device Detection Packet (DDP). If a device
is not found (removed), the DC sends the Device
Removal Packet (DRP).
The sequence of operations can be categorized into three
different processes as follows.
2.2.1. Device initialization process
1. On reset, the HC sends Device Checking Packet (DCP) to
each DC. A DC performs a scan on its ADs and sends a
DDP to the host for each device found.
2. If the AD information is found on the HC, it will
automatically pop up the window for device control. If
user acknowledges the device found, an ACKP would be
sent back to the DC, otherwise NACKP would be sent.
3. If the new AD is not stored in the HC, HC will pop up
window to request user to configure the new AD. If user
acknowledges and configures the device, the ACKP
would be sent back to the DC, otherwise NACKP would
be sent.
2.2.2. Periodic checking process
1. Host periodically sends the DCP to a DC to check if it is
working properly and whether any new AD has been
added or removed. If HC does not receive an acknowledgment
from the DC, the host assumes that the DC is
not working properly or has been removed. The HC will
stop transferring any information to the AD of that DC.
2. When a DC finds a new AD or a removed AD while
performing a DCP, it sends DDP or DRP to the HC.
Depending on whether the HC acknowledges it or not,
the DC updates the local descriptor table.
2.2.3. Data transaction process
1. CMDP (Command packet) will be sent from the HC to a
DC in order to control the AD or to retrieve status
information of the AD.
2. If the packet received by the DC is to control an AD and
no data is required in return, an ACKP will be sent back
to the HC, after executing the necessary commands.
3. If the command packet requests for data, a DATAP (Data
packet) will be sent back to HC.
All packet formats are described in Section 2.3.