07-04-2012, 04:49 PM
MICROCONTROLLER BASED MEASUREMENT
ppt of microcontroller based measerments.pptx (Size: 721.93 KB / Downloads: 89)
INTRODUCTION :
Microcontrollers are widely used in embedded system products.
A printer is an example of embedded system since the controller inside it perform only one task ; namely getting the data and printing it.
A variety of application can be loaded in microcontroller and run.
Various embedded products are keyboard ,printer ,modem ,disk controller ,sound card , mouse and so on.
Each one of these peripherals has microcontroller inside it that perform only one task.
BASICS OF ULTRA SONIC WAVES
Ultrasounds starts at 20kHz where human capacity of hearing ends.
Ultrasonic waves are used because of its high frequency resulting in to maximum traveling capacity i.e. less distortion..
APPLICATION:
μC Based Digital Fuel level indicators
μC based prepaid electricity billing automation.
μC based temperature measurement
μC based bike speed (speedometer) measurement
μC based air humidity measurement
μC based air velocity measurement
DESCRIPTION OF COMPONENTS:
Ultrasonic generators use piezoelectric materials such as zinc or lead zirconium tartrates or quartz crystal.
The material thickness decides the resonant frequency when mounted and excited by electrodes attached on either side of it. The medical scanners used for abdomen or heart ultrasound are designed at 2.5 MHz In this circuit, a 40kHz transducer is used for measurement in the air medium.
The velocity of sound in the air is around 330 m/s at 0°C and varies with temperature
CIRCUIT DESCRIPTIONS
The 40kHz pulse bursts from the microcontroller are amplified by transistor T5.
Inverting buffer CD4049 drives the ultrasonic sensor used as the transmitter. Three inverters (N1, N2 and N3) are connected in parallel to increase the transmitted power.
This inverted output is fed to another set of three inverters (N4, N5 and N6). Outputs of both sets of parallel inverters are applied as a push pull drive to the ultrasonic transmitter