Technion-Israel Institute of Technology Electrical Engineering Department High Speed Digital Systems Laboratory Project subject: wireless biofeedback system Performed by: Yarovoy Boris Krassowizki Alexander Instructor: Sinyuk Konstantin

What is Biofeedback? The principle of biofeedback is to collect data about person’s emotional state and to perform appropriate actions accordingly to this state. Also it can be used to influence on the people, to force certain mental and physical state.

Project objective Building of Biofeedback system which collects data(temperature and skin resistance) from a person and creates influence(light and sound) on it accordingly, minimizing user interface Building of Biofeedback system which collects data(temperature and skin resistance) from a person and creates influence(light and sound) on it accordingly, minimizing user interface

PICMicrocontroller PC System description Temperature sensor Skin resistance circuit I2C A/D ControlPWM UART Influence

System components Digital temperature sensor of TI TMP100Digital temperature sensor of TI TMP100 with I2C interface with I2C interface Skin resistance circuit (self built):Skin resistance circuit (self built): TI amplifiers,TI analog switches TI amplifiers,TI analog switches Microchip microcontroller PIC18f452Microchip microcontroller PIC18f452 with I2C interface (with demo board) with I2C interface (with demo board) Sound and light sources :Sound and light sources : LED’s and buzzer on PIC demo board LED’s and buzzer on PIC demo board PCPC

System components PIC microcontrollerPIC microcontroller PIC 5 I/O I/Oports PWM module UART module MSSP module MSSP used as I2C interfaceMSSP used as I2C interface MPLAB2 module for debuggingMPLAB2 module for debugging C-compiler with support CC-compiler with support C functions for programming functions for programming PIC peripherals PIC peripherals Evaluation board with LED’sEvaluation board with LED’s and buzzer and buzzer A/D

System components Demo boardDemo board Buzzer Led’s Buzzer-sound sourceBuzzer-sound source Led’s –light sourceLed’s –light source To perform connectionTo perform connection to PC RS-232 port with to PC RS-232 port with serial communication serial communication hardware are used hardware are used I/O ports pins RS-232 connector and support hardware PIC PWM

Components description Temperature sensorTemperature sensor The TMP100 require no external components for operation except for pull-up resistors (10 kOhm) on SCL, SDA (I2C interface pins), although a 0.1uF bypass capacitor is recommended.

TMP 100 Vdd To I2C controller SCL SDA ADD1 (Input) ADD0 (Input) 0.1uF. Temperaturesensor There are pull up resistors connected to SCL and SDA lines

Connecting T sensor to PIC PIC I/O port C with I2C pins T sensor SDA SCL SDA: digital temperature data SCL: serial clock TMP100 resolution : 12 bits (up to C) with conversion rate 3 samples/s A/D Temperature register ADD0 ADD1 I/O port MSSP module in I2C mode

Connecting T sensor to PIC ADD0 and ADD1 lines used to select T-sensor address on I2C bus.They received from I/O pins of PIC. Data is sent in 2 bytes (12 bits value). For programming MCC18 compiler library functions are used (I2C interface and I/O ports configuration) I2C interface implemented in MSSP module of PIC working in I2C mode

Components description Skin Resistance CircuitSkin Resistance Circuit Current up to 16 uA flows through human’s fingers and voltage difference between fingers is measuredCurrent up to 16 uA flows through human’s fingers and voltage difference between fingers is measured AC current is preferred for it reducesAC current is preferred for it reduces changes to human’s tissue changes to human’s tissue After voltage is measured it is amplifiedAfter voltage is measured it is amplified and transmitted to PIC and transmitted to PIC

Skin resistance circuit Current source circuit men Voltage value Amplifier circuit with selectable gain PIC Measurement borders: 15 Ohm – 300 kOhm

Current source circuit 200k S1 S2 Amp V3 V2 Vdd 1/5*Vdd 3/5*Vdd S3 AMP - TI’s instrumentation amplifier Sx – TI’s bi-directional analog switch: control switches’ pins connected to I/O ports pins of PIC control switches’ pins connected to I/O ports pins of PIC ‘0’=OFF,’1’=ON ‘0’=OFF,’1’=ON S1 and S2 need to change current direction S1 and S2 need to change current direction S3 need to allow or stop current through a man S3 need to allow or stop current through a man Iout Iout=(V3-V2)/200K Vman

Amplifier circuit S4S5S6S7S8 Amp Vman PIC A/D The gain of amp. depends on resistance value connected to it To select appropriate resistance switches are used Circuit allows 5 gains: 1,2,5,10,20 20k40k80k200k400k

Connecting resistance circuit to PIC PIC I/O port A with analog with analog input pins A/D I R V Amp A/D result is signed 10 bit Programming of A/D hardware and switches of resistance circuit is done with MCC18 compiler A/D functions and definitions

Connecting PIC to PC PIC UARTmodule COMport PC RS-232Serialport Demo board I/O port pins To enable connection on PC Visual Studio functions for usage of communication devices are used On PIC UART module used for serial communication (MCC18 UART module C functions)

Flow of data and control T and R measurements PIC receives data with I2C interface and A/D Gain adjusting Switches control Sending data to PC with UART module Influence Algorithm (on PC) Receiving answer(UART) and running buzzer and led’s (demo board) RS-232 serial port

Project status Accomplished: building and testing resistance circuitbuilding and testing resistance circuit learning different modules(software)learning different modules(software) receiving resistance data on PICreceiving resistance data on PIC To be done: to accomplish receiving temperature on PICto accomplish receiving temperature on PIC to accomplish serial connection PIC  PCto accomplish serial connection PIC  PC run and test overall systemrun and test overall system

Schedule Finish temperature measurement Finish PIC  PC connection – 3.11 Ensemble overall system Debug the system – 15.11