AT89SAC datasheet, AT89SAC circuit, AT89SAC data sheet: ATMEL – 8-bit Microcontroller with 4K Bytes In-System Programmable Flash. Operating Temperature: Standard; Dissipation Power: Standard; Application: MP3/MP4 Player; Supply Voltage: Standard; Model Number: AT89SAC; Type. Microchip Technology / Atmel. Mfr. #. AT89SAU. Description: 8-bit Microcontrollers – MCU 4K ISP FLASH TO V – 24MHz. Compare With Current Part.
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Skip to main content. Log In Sign Up. In this work, a microcontroller-based automatic school bell is designed.
This circuit uses a programmed microcontroller chip to schedule the school teaching and break periods so that for every start or end of a period a bell is automatically rang.
This design finds a tremendous use at primary and secondary school levels where the teaching sections can span over eight periods including breaks.
AT89SAC Datasheet(PDF) – ATMEL Corporation
The advantage here is at89s15 the bell rings at the start of each period without any human intervention to a great degree of accuracy. The time 24wc results are compared with that obtained with a clock, however, some drift is noticed, which is negligible. Automation, break period, time-select switching unit, pull-up resistors, oscillator characteristics. A bell is a percussion instrument used in schools that tells the students when it is time to 2.
Design go to class in the morning and when it is time The entire circuit is designed in blocks of to change classes during the day.
Typically, the different modules as shown in Fig. The first bell tells the students that it is time to subsequent sessions describe the various report to class. The bell is an important modules that are included in the instrument in both primary and secondary microcontroller based automatic school bell. Clock towers or bell towers circuits require a dc source for their operation can be heard over long distances which was Theraja and Theraja The dc power especially important in the time when clocks supply converts the standard V, 50 Hz ac were too expensive for widespread use.
The available on wall outlets into a constant dc bell shape is usually an open-ended hollow voltage. It is one of the most common drum which resonates upon being struck. From earliest times, they were shown in Fig. The use of bells in churches spread This unit is responsible for the selection through Europe from the 6th to 11th centuries of timing suitable for a particular school.
The timing schedules available for this design. Each switch from S1 to S10 represents a single Table 1. A single schedule has a total of eight periods with a breakfast after the fourth period. The eleventh switch, S11, provides a room for any emergency that arises which will lead to the bell ringing, thus called an emergency switch. This emergency switch is common for every schedule selected and active at any point in time during the school hours.
Each switch is connected from the pins of microcontroller to the ground. Every microcontroller has ability to sink or source current. The type of microcontroller used in this design is AT89S Functional block diagram of the microcontroller based automatic school bell. Circuit diagram of the time-select switching unit. From the datasheet of AT89S51ports 1, 2 and 3 can sink current of about 1. Therefore, by taking the sinking current to be 0. Circuit diagram of power supply unit.
The circuit diagram of this unit is as The pins that were connected to the shown in Fig. The limiting resistance can be switches are held HIGH by the pull-up calculated as follows. According to Boylestad resistors. From the datasheet of AT89S51 bidirectionaltherefore, if any of the switches,the sinking current of port 0.
Therefore, which 24ca as the input to the microcontroller. The major component in this project LED1, which 24zc green color, glows design is the AT89S51 microcontroller which immediately after a schedule has been selected, controls, coordinates and directs all the indicating that the school bell is active. It activities and behaviors of this design. Most remains ON throughout the school periods. The oscillating at every second after 244ac last period AT89S51 addresses both of these needs by of the school hour is over.
The input from the timing unit to 24ca 2. The output of this goes to invert a digital signal. It has a single input and the LED indicator and inverter units as shown a single output. The symbol and truth table for in Fig. In this In this design, the hex inverter is design, a quartz crystal was used. Therefore, since a crystal was used, 33 has 14 metallic pins connected to the outside of pF was chosen for both capacitors C1 and C2 a plastic case containing the silicon chip.
The as shown zt89s51 Fig. The power supply connections to the IC are 2.
Complete circuit diagram of an automatic school bell. Flow chart for the instructions that execute the timing. This means that whatever comes out of P0.
In an 0 1 electronic circuit, the input signal 1 or 0 is usually applied to the base of the transistor, 1 0 which causes the collector-emitter junction to become a short or an open circuit. In the fully ON state, the voltage VCE across the transistor is almost zero and the transistor is said to be saturated Fig. Inverter symbol and truth table. The load resistance, which is the collector resistance, is the resistance of the relay coil as shown in Fig.
A hex inverter pin configuration. Circuit diagram of the relay driver unit. The NPN semiconductor switches e. Thus, from the and integrated circuits cannot provide. Also, datasheet of 2N The diagram in Fig. Notice that the logic circuit and dc motor have The minimum value of base current separate power supplies. The dc motor operates by providing a rotary motion, which drives the mechanical Therefore, the voltage across the base devices that result in bell ringing.
When the output of the inverter goes LOW, the transistor stops conducting and the where Vin is the output voltage of the inverter relay contacts spring back to their NC position.
The maximum value of RB that will allow a minimum IB of 0. The actual value iL Relay used should be much less.
AT89SAC Price & Stock | DigiPart
Therefore, the base resistance, RB was chosen to be 2. Illustration of a protection diode. A relay provides total isolation between the triggering source The circuit in Fig. This circuit diagram of the design. Conclusion The basic design of the Automatic After testing the bell, the following School Bell mainly for Primary and Secondary tabulated results shown in Table 2 were Schools in this work remains the same though obtained.
This will ring Table 2. Results obtained from the test. There are different times per period varying from one school to the other. The basic design provides an opportunity of selecting the suitable time schedule for every school by momentarily pressing one of the push-to-on switches.
This signals the microcontroller to carry out the specific task, thereby ringing the bell at a regular time interval. Therefore, from the results obtained, it can be concluded that the aim of this work has been practically and theoretically achieved. Various deductions can be made from the Boylestad, R. The drift in 45 min is Electronic Devices and Circuit Theory. Principles of microsecond instructions that were not taken Electronics. Chand, Ram Nagar, into consideration during the programming.
According to the results in Table 2, it was Theraja, B. A observed that at the end of the school periods Textbook of Electrical Technology.
Thus, this is accurate enough for most applications.
Microcontroller IC AT89S51-24AC
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