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MICROPROCESSOR SYSTEM FOR MEASURING NON-ELECTRICAL QUANTITIES. Zivko Kokolanski, Cvetan Gavrovski zivko.kokolanski@feit.ukim.edu.mk cvetang@feit.ukim.edu.mk. STRUCTURE OF THE MEASURING SYSTEM MEASURING CIRCUITS - LLUMINANCE MEASUREMENT - TEMPERATURE MEASUREMENT
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MICROPROCESSOR SYSTEM FOR MEASURING NON-ELECTRICAL QUANTITIES Zivko Kokolanski, Cvetan Gavrovski zivko.kokolanski@feit.ukim.edu.mk cvetang@feit.ukim.edu.mk
STRUCTURE OF THE MEASURING SYSTEM MEASURING CIRCUITS - LLUMINANCE MEASUREMENT - TEMPERATURE MEASUREMENT - HUMIDITY MEASUREMENT - PRESSURE MEASUREMENT PROCESSING MODULE MEASURING ALGORITHM TECHNICALL CHARACTERISTICS CONCLUTION OUTLINE
Power Supply • Analog • Signal • Processing Processing Module Display and Communication STRUCTURE OF THE MEASURING SYSTEM
ILLUMINANCE MEASUREMENT • Most commonly used detectors: • silicon photodiodes • photoconductive cells Advantages of the photodiodes: • higher sensitivity • faster response time • higher stability and linearity • Photodiode: BPW34 • high sensitivity • fast response time • visible and near IR (800nm)
TEMPERATURE MEASUREMENT • Thermistor KTY21-122 • -55 to 150oC • non linear y = 0,0167x2 + 7,0979x + 827,6
HUMIDITY MEASUREMENT • Sensor 808H5V6 • capacitive type • 0-100% RH
PRESSURE MEASUREMENT • Pressure sensor STS030A • measuring strips based • 0-2000 hPa • 150 mV output voltage
FF FF FE FE FD FD FC FC PROCESSING MODULE • Microcontroller PIC 16F877 • 4 bidirectional ports • 8 channel 10 bit A/D converter sync illuminance sync temperature sync humidity sync pressure
PARAMETER SETTING LCD INITIALISATION A/D CONVERSION (20 SAMPLES) AVERAGING SERIAL INTERFACE INITIALISATION CORRECTION SERIAL TRANSMITION A/D CONVERSION SETTING LCD WRITE ILLUMINATION MEASUREMENT TEMPERATURE MEASUREMENT HUMIDITY MEASUREMENT PRESSURE MEASUREMENT MEASURING ALGORITHM
CONCLUTION • The presented paper describes a practical measuring system, which allows measurement, transfer and display of the moment values of four physical quantities: temperature, pressure, humidity and illumination • The measuring system uses a serial RS-232 port for computer communication • Further development of the measuring system is planned in future, in a way of enlarging the measuring quantities with measurements of ionizing radiation and wireless data transmission