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LCD based digital alarm clock with digital thermometer using 8051 microcontroller (AT89C51)

Summary

Developed By: 
Himanshu Choudhary

This project works as a digital clock wherein a user can also set alarm. Additionally, it also works as a digital thermometer to specify the ambient temperature. Both, the clock and temperature are displayed on a 16x2 LCD screen using the 8051 microcontroller (AT89C51). AT89C51 is an eight bit controller which belongs to the 8051 family of microcontrolers.

LCD based digital alarm clock with digital thermometer using 8051 microcontrolle

Description

 

Celsius scale thermometer displays the ambient temperature through a LCD display. It consists of two sections. One is that which senses the temperature. This is a LCD based Digital Alarm clock with thermometer function temperature sensor LM 35. The other section converts the temperature value into a suitable number in Celsius scale which is done by the ADC0804. A digital thermometer can be easily made by interfacing a temperature sensor to the microcontroller AT89C51. The temperature sensor used in the project isLM35. The LM 35 IC generates a 10mV variation to its output voltage for every degree Celsius change in temperature. The Output of the temperature sensor is analog in nature so we need an analog to digital convertor for converting the analog input to its equivalent binary output.ADC 0804 is an analog to digital convertor IC used in the project. 0804 is a single channel convertor which converts the analog input up to a range of 5V to an equivalent 8-bit binary output.  

This project incorporates the functionality of a digital clock and a digital thermometer. The digital clock works in 12 hour mode and is configured by programming the 8051 microcontroller (AT89C51). The program uses a delay function for producing a delay of 1 second. The clock and alarm times can be set through a set of external tactile switches.

 

The digital thermometer employs a temperature sensor LM35. The sensor responds to the temperature change by giving varying output. These analog signals of LM35 are converted to digital equivalent by ADC0804. The reference voltage (Vref) should be set properly corresponding to the desired temperature range. The data bits are taken as input by the microcontroller at port P0. The microcontroller AT89C51 also gives control signals to ADC0804.
 

Circuit Diagram

Video

Code

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Components

Presets | Variable Resistors
Preset
 
A preset is a three legged electronic component which can be made to offer varying resistance in a circuit. The resistance is varied by adjusting the rotary control over it. The adjustment can be done by using a small screw driver or...
LM35 Temperature Sensor Image
LM35 Temperature Sensor

LM35 is a precision IC temperature sensor with its output proportional to the temperature (in oC). The sensor circuitry is sealed and therefore it is not subjected to oxidation and other processes....

Piezo Buzzer
Piezo Buzzer
 
The piezo buzzer produces sound based on reverse of the piezoelectric effect. The generation of pressure variation or strain by the application of electric potential across a piezoelectric material is the underlying...
AT89C51 Microcontroller, Atmel 89C51 Controller Image
AT89C51 Microcontroller

AT89C51 is an 8-bit microcontroller and belongs to Atmel's 8051 family. ATMEL 89C51 has 4KB of Flash programmable and erasable read only memory (...

16 x 2 LCD | 16x2 Character LCD Module
LCD

 

LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications. A 16x2 LCD display is very basic module and is very commonly used in various devices and circuits. These modules are preferred over seven segments...

ADC0804 | ADC 0804
ADC0804

Analog to digital converters find huge application as an intermediate device to convert the signals from analog to digital form. These digital signals are used for further processing by the digital processors. Various sensors like temperature, pressure, force etc. convert the physical characteristics into electrical signals that are analog in nature....

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