3. Introduction
• It is the study of brain functions.
• A collaboration in which a brain accepts and controls a mechanical device.
• Direct communication pathway between a brain and an external device.
• Thus BCI extracts electro-physical signals from suitable components of the brain and process
them to generate control signals for computers, robotic machines or communication devices.
“ A Brain-Computer Interface is a communication system that do not depend on peripheral nerves
and muscles “
[J. R. Wolpaw et al. “Brain-computer interface technology: A review of the first international
meeting,” IEEE Trans. Rehab. Eng., vol. 8, no. 2, pp. 164–173, 2000]
4. What is BCI
• Brain-Computer Interfaces (BCI)
• Interaction between the human neural system and machines
• Goal
• Enabling people (especially disabled) to communicate and control devices by mere thinking.
• BCI is a control system
5. Literature survey
A brain–computer interface (BCI), sometimes called a mind-machine interface (MMI), direct
neural interface (DNI), or brain–machine interface (BMI), is a direct communication pathway
between the brain and an external device. BCIs are often directed at assisting, augmenting, or
repairing human cognitive or sensory-motor functions.
Research on BCIs began in the 1970s at the University of California, Los Angeles (UCLA)
under a grant from the National Science Foundation, followed by a contract from DARPA.The
papers published after this research also mark the first appearance of the expression brain–computer
interface in scientific literature.
The field of BCI research and development has since focused primarily on neuroprosthetics
applications that aim at restoring damaged hearing, sight and movement. Thanks to the
remarkable cortical plasticity of the brain, signals from implanted prostheses can, after adaptation, be
handled by the brain like natural sensor or effector channels. Following years of animal
experimentation, the first neuroprosthetic devices implanted in humans appeared in the mid-1990s.
6. Methodology
• To control the wheelchair, EEG signals are needed.
• Here this paper describes EEG signals through a BCI interface.
• In this system we have a tendency to use simple unipolar electrode to record
EEG signal from the forehead to construct a Brain-Computer Interface (BCI)
primarily controls electrical wheelchairs through ZigBee for unfit patients.
• The experimental results confirmed that this system will offer a convenient
manner to control an electrical wheelchair.
7. Specification
PIC16F877A:
a) 256 Bytes EEPROM
b) Maximum operating frequency: 20MHz
c) 368bytes Internal SRAM
d) 8-channel, 10-bit ADC
e) Operating Voltage range 4.5V.
II. ZigBee transceiver:
a) 2.4 GHz IEEE 802.15.4/ZigBee RF transceiver
b) Wide supply range: 1.8 V – 3.8 V
c) Data rate: 250 kbps
d) RF frequency range 2.394 - 2.507 GHz
e) Transmission range: 50 meters
III. L293D driver IC:
a) Wide Supply-Voltage Range: 4.5 V to 36 V
b) Output Current 1 A per Channel (600 mA for L293D)
c) Peak Output Current 2 A per Channel (1.2 A for L293D)
11. Power Supply – Circuit Description
• The operation of power supply circuits built using filters, rectifiers, and then voltage
regulators. Starting with an AC voltage, a steady DC voltage is obtained by
rectifying the AC voltage, Then filtering to a DC level, and finally, regulating to
obtain a desired fixed DC voltage. The regulation is usually obtained from an IC
voltage regulator Unit, which takes a DC voltage and provides a somewhat lower
DC voltage, Which remains the same even if the input DC voltage varies, or the
output Load connected to the DC voltage changes.
12. About Microcontroller
• PIC16F877A microcontroller is used for this project
• It is 8-bit Microcontroller
• System is RISC Architecture
• It has Small set of Instruction set
• It has 35-Instructions only
• Compatibility: avail 28/40 Pin ICs
13. Microcontroller overview
• Operating Speed Max 20 MHz, Voltage-(2-5.5)v
• Memory:
Flash Program 8Kx14 Words,
RAM 368 Bytes,
EEPROM Data Memory 256 Bytes
• Low power, High speed Flash/EEPROM Technology
14. Features of Microcontroller
• It has 5 Ports for Internal and External usage
• It has on chip Timers. 3 Timers are avail
• It has in built Analog to Digital Converter
• In built Multiplexer availability for signal Selection
• It has serial as well as Parallel Communication facilities
• In built Capture, Compare and Pulse width modulation
17. USART pins inPIC16f877A
• The USART always transmits data on pin RC6/TX
• The USART always receives data on pin RC7/RX
• The RS-232 standard defines lots of other signals other than TX and RX used for
handshaking.
18. Voltages
• The USART input/output uses 0V for logic 0 and 5V for logic 1.
• The RS-232 standard (and the COM port) use +12V for logic 0 and –12V for logic
1.
• To convert between these voltages levels we need an additional integrated circuit
(such as Maxim’s MAX232).
21. Zigbee module
• The XBee and XBee-PRO OEM RF Modules were engineered to meet IEEE 802.15.4
standards and support the unique needs of low-cost, low-power wireless sensor
networks. The modules require minimal power and provide reliable delivery of data
between devices.
• The modules operate within the ISM 2.4 GHz frequency band and are pin-for-pin
compatible with each other
25. Data Flow diagram
• The XBee®/XBee-PRO OEM RF Modules interface to a host device through a logic-level asynchronous
serial port. Through its serial port, the module can communicate with any logic and voltage compatible
UART; or through a level translator to any serial device (For example: Through a Digit proprietary RS-232 or
USB interface board).
27. Embedded C
• The C for microcontrollers and the standard C syntax and semantics are slightly different. The former is
aimed at the general purpose programming paradigm whereas the latter is for a specific target microcontroller
such as 8051 or PIC. The underlying fact is that everything will be ultimately mapped into the microcontroller
machine code. If a certain feature such as indirect access to I/O registers is inhibited in the target
microcontroller, the compiler will also restrict the same at higher level. Similarly some C operators which are
meant for general purpose computing are also not available with the C for microcontrollers. Even theoperators
and constructs which may lead to memory inefficiency are not available in C programming meant for
microcontrollers.
28. Embedded C(cont…)
• Be aware that the target code should fit in the limited on-chip memory of the processor. Even the I/O
functions available in standard C such as printf() or scanf() are either not made available in C compilers for
microcontrollers or advised not to use them. These functions eat up lot of memory space and are not time-
efficient owing to the dragging of supporting functions like floating point routines and lot of delimiters.
Another striking difference in case of embedded systems programs is that they do nothave the umbrella or
support of the operating system. The programmer has to be accustomed with the absence of system calls
which makes life easy in traditional C.
29. MPLAB IDE
• MPLAB IDE is a Windows Operating System (OS) software program that runs on a PC to develop
applications for Microchip microcontrollers and digital signal controllers.
• It is called an Integrated Development Environment, or IDE, because it provides a single integrated
"environment" to develop code for embedded microcontrollers.
• The MPLAB IDE has both built-in components and plug-in modules to configure the system for a variety of
software and hardware tools.
31. Disadvantages
THE DRAWBACKS OF BCI :
- THE BRAIN IS INCREDIBLY COMPLEX,
- THE SIGNAL IS WEAK & PRONE TO INTERFENCE,
- THE EQUIPMENTS IS LESS THAN PORTABLE,
33. References
1) Jzau-Sheng Lin,Kuo-Chi Chen and Win-Ching Yang, “EEG and Eye-
Blinking signals through a BrainComputer Interface Based Control for
Electric Wheelchairs with Wireless Scheme”.
2) K. Kiguchi and Y. Hayashi, “Motion Estimation based on EMG and EEG
Signals to Control Wearable Robots”, IEEE International Conference on
Systems, Man and Cybernetics, pp. 4213-4218, 2013.
3) S.Y. Cho, A. P. Vinod, and K. W. E. Cheng, "Towards a Brain Computer
Interface Based Control for Next Generation Electric Wheelchairs ", Int.
Can! on Power Electronics Systems and Applications, pp. 1-5,2009.
4) K. Nielsen, A. Cabrera, and O. Nascimento, "Eeg based bci - towards a
better control: Braincomputer interface research at
aalborguniversity,"IEEE Transactions on Neural Systems and
Rehabilitation Engineering., vol. 14, no. 2, pp. 202-204, 2006.
5) G. E. Fabiani, D. J. McFarland, J. R. Wolpaw, and G.
Pfurtscheller"Conversion of EEG activity into cursor movement by a
brain-computer interface (BCI), IEEE Trans. on Neural Systems and
Rehabilitation Eng., vol. 12, no. 3, pp. 331-338, Sep. 2004.
