MICROPROCESSOR BASED CONTROL SYSTEM
microprocessor are essential for many of the products we use every day such as TVs cars, radio, home appliance, and computers. microprocessor based controls also called microcontrollers. microcontroller is a digital integrated circuits which serves as a heart of many modern control applications.
microprocessor and microcontrollers are similar but the architecture of the both differs in the applications domains. microprocessor are employed for high speed applications such as desktop and laptop computers whereas the microcontroller are employed in automations and control applications such as microwave ovens, automatic washing machines, dish washers, engine management system, DVD players etc.
microcontrollers are embedded inside some other devices so that they can control the features or actions of the product. therefore , it is also called embedded controller.
A microcontroller generally has the main CPU core, ROM/EPROM / RAM and some accessory such as timers , pulse width modulators , A/D converter and I/O controller all integrated into one chip, micro controller is a computer on a chip that is programed to perform almost any control, sequencing , monitoring, and display function.
EXAMPLES OF MICROPROCESSOR BASED CONTROL SYSTEM:
AUTOMATIC FILM CAMARA:
the automatic camera using film has the features of automatic focusing and exposer. the basic elements of the microprocessor based control system used in as automatic film camera for focusing and exposure.
the working of auto focusing aperture control for auto-exposer is explained as follows.
The auto focusing is achieve by using range sensor. when the system is switch on to activation mode,the camera is pointed at the object to take the snap. the microprocessor takes the input signal from the range sensor. this signal is processed to send the output signal to the lens position drive to move the lens for achieving auto focusing. The microprocessor gets the feedback signal about the lens positions from the range sensor which is the used to modify the lens positions to get the desired positing of focus.
APETRTURE CONTROL FOR AUTO EXPOSURE:
the light sensor is used to achieve an aperture control for auto-exposer. when the shutter switch is pressed to the initial position , the microprocessor calculates the shutter speed and aperture settings based on the input from a light sensor. it the gives output signal to the viewer finder. when the shutter switch is pressed to the final position, the microprocessor gives signal to the aperture control drive to open the shutter to the required position. the shutter is kept open for the preset amount of time and then it is closed. after photograph has been taken, the microprocessor sends an output signal to the motor drive to advance the film for the next snap.