FEATURES OF 8259:
1. It is programmed to work with either 8085 or 8086 processor.
2. It manage 8-interrupts according to the instructions written into its control registers.
3. In 8086 processor, it supplies the type number of the interrupt and the type number is programmable. In 8085 processor, the interrupt vector address is programmable. The priorities of the interrupts are programmable.
4. The interrupts can be masked or unmasked individually.
5. The 8259s can be cascaded to accept a maximum of 64 interrupts.
The water level Controller is a reliable circuit, it takes over the task of indicating and Controlling the water level in the overhead water tanks. The level of the water is displayed in the LED Bar graph. The Copper probes are used to sense the water level. The probes are inserted into the water tank which is to be monitored. This water-level Controller-cum-alarm circuit is configured around the well-known 8 bit Microprocessor 8085. It continuously monitors the overhead water level and display it and it also switch Off the Motor when the tank fills and it will automatically switch On the Motor when the water level is low. The Microprocessor will also indicate the water level over the LED display. All the input and output functions are done through the Programmable Peripheral Interface IC 8255.
An alarm clock is a clock that indicates a pre-set time by producing sound at that time. This functionality of digital clock is used to awaken people or remind them of something. This circuit is an extension to the digital clock with time setting option. Here an extra switch is provided to set the alarm. While the alarm is set, the clock time does not stop and runs in the background.The circuit is build around 8051 micro-controller (AT89C51) and uses LCD to display time.
Fahrenheit scale digital thermometer is a temperature indicator which displays temperature in Fahrenheit scale. It is similar to Celsius scale digital thermometer, except a little modification in the microcontroller program. The temperature sensed in Celsius scale in the Celsius scale thermometer project is converted into the Fahrenheit scale temperature just by using the Celsius to Fahrenheit conversion formulae. This project also uses 8051 microcontroller (AT89C51).
A digital clock is one that displays time digitally. The circuit explained here displays time with two ‘minutes’ digits and two ‘seconds’ digits on four seven segment displays. The seven segment and switches are interfaced with 8051 microcontroller AT89C51. This circuit can be used in cars, houses, offices etc.
A counter that can change its state in either direction, under control of an up–down selector input, is known as an up–down counter. The circuit given here can count numbers from 0 to 9999 in up and down modes depending upon the state of the selector. It can be used to count the number of persons entering a hall in the up mode at entrance gate. In the down mode, it can count the number of persons leaving the hall by decrementing the count at exit gate. It can also be used at gates of parking areas and other public places.
This circuit divided in three parts: sensor, controller and counter display. The sensor would observe an interruption and provide an input to the controller which would run the counter in up/down mode depending upon the selector setting. The same count is displayed on a set of 7-segment displays through the controller.
