micro_timer

Microwave Controller using ATmega8 – AVR Project

Microwave Controller’s User Interface

microwave timer using avr atmega8
Fig. Microwave Timer using AVR ATmega8

 

The user interface has the following parts.

Output Device: A 16×2 alphanumeric LCD Module is used as the main output device. It can display numbers, alphabets and few symbols. It can show two line and each line can have 16 characters. The backlight enables the text to be visible even in dark.

A buzzer beeps when the system receive input from the user and the input is successfully processed. For example if the user presses 10 MIN button to increment timer by 10 min and this is successfully carried out the buzzer beeps. But if the timer is already at the maximum setting (90 minutes) the operation could be carried out, so the buzzer does not beeps.

This buzzer also beeps a few time when the food is ready (countdown is finished)

Input Device: Input from user is received by a keypad which has seven push buttons. The details of button is given below.

Button Function
Microwave Selects Microwave mode.
Grill Selects Grill mode.
10 MIN Increment timer by 10 minutes.
MIN Increment timer by 1 minute.
10 SEC Increment timer by 1 sec.
STOP/Clear
  1. If the microwave is in on condition, this button turns it off and pauses the timer count down.
  2. If you are setting the timer, this button clears the time to 00:00. Useful if you have made some mistake during setting.
START
  1. If you have paused the timer to open the oven and check the status of food, this button will resume the timer.
  2. After time is setup you need to press this to turn the microwave (or grill).

 

keypad for microwave timer
Fig. Keypad

 

Controlling Relays

Their are two controlling relay

  1. The microwave relay: this controls power to the microwave function.
  2. The grill relay: this controls the power to the grill function.

Using the Microwave Timer

The first screen of timer asks you to choose one of the operating modes. You can choose from Microwave or Grill functions. Press the respective button on the keypad to choose the mode.

microwave timer home screen
Fig. Home Screen

 

Then you are presented with the following screen.

time entry
Fig. "On" time input.

At the top left it shows the mode i.e. Micro for Microwave mode and Grill for Grill mode. You can press the mode keys to change the mode in this stage too.

switch mode
Fig. Switching between modes.

 

In the center it shows the timer. Here you can set an "on" time for up to 90 minutes.

To set the time you can use the following buttons

10 MIN To increment the timer by 10 minutes
MIN To increment the timer by 1 minute
10 SEC To increment the timer by 10 seconds

three buttons are provided to quickly set up desired time.

Once you are satisfied with your set time, press the START button. This will switch on the selected function (microwave or grill) and start the countdown. You can see the time decrementing on the LCD screen.

When the countdown reaches 00:00 the relay associated with the selected function (microwave or grill) will be switched off. And the screen will show Ready ! Message. When the food is ready buzzer will give long beeps few times. So that the person cooking is alerted.

At this stage (Ready) press any key to go to home screen.

ready
Fig. Ready

 

Clear Function

You can press STOP/Clear button to reset the time to 00:00 during time entry.

Change Mode Function

You can press Microwave or Grill buttons (function select buttons) to change the function anytime during time entry.

switch mode
Fig. Switching between modes.

 

Pause Function

You can press STOP/Clear button during countdown phase to pause the timer and to switch of the associated relay of selected function (microwave or grill). This will enable you to open the door of oven and have a look at the food being cooked. During this, a PAUSED! message will be displayed on the LCD. Once you are done with your inspections you can close the door and press the START button. This will resume the cooking process.

timer paused
Fig. Switching between modes.

 

Quick Start Function

Quick start function does the following tasks at the single press of button.

  1. Select mode Microwave.
  2. Set on time to 30 sec.
  3. Turn on the microwave.
  4. Start the countdown.

You can press START button at the home screen to achieve quick start.

Once the count down has started you can press START to increase on time by 30 seconds.

Hardware for Microwave Timer

The timer is built around ATmega8 AVR microcontroller. This is a very small single chip computer which runs a small program stored in its flash memory. This program provides all the functionalities of the timer.

Our microcontroller controls the LCD Module, the relays and the buzzer. It receives user input from the keypad.

MCU Core

Microcontroller chip requires a basic circuitry for functioning. This consists of the following parts.

  • Power supply: This provides 5v regulated DC power to the microcontroller. It receives input 12V DC from a 12V adapter.
  • ISP Header: In circuit programming header. Used to easily connect an ISP Programmer to upload programs to the Microcontroller.
  • Reset Circuit: A pull up resistor holds the RESET pin of MCU to high state. This is required for normal operation.
atmega8 basic circuit without crystal
Fig. ATmega8 Basic Circuit

Bill of Materials

S. No. Item Reference Value Quantity
1 1/4 Resistor R1 330 ohms 1
2 1/4 Resistor R2 4K7 1
3 Electrolytic Capacitor C1 470uF 1
4 Ceramic Capacitor C2,C3,C4,C5 0.1uF 4
5 ATmega8 U1 - 1
6 7805 Regulator U2 - 1
7 1N4007 D1 - 1
8 LED GREEN D2 - 1
9 Inductor L1 10uH 1
10 Push to on – micro switch S1 - 1
11 On/Off Switch SW1 - 1
12 DC Socket X1 - 1
13 10 PIN FRC Box Header X2 - 1

We use a ready made low cost development board for this purpose.

28 pin avr development board
Fig. 28 pin AVR development board

LCD Interface

The schematic for LCD interface is shown below.

ATmega8 LCD Interface Schematic
Fig. LCD Interface

Bill of Materials

S. No. Item Reference Value Quantity
1 1/4 Resistor R1 100 ohms 1
2 Preset RV1 10K MAX 1
3 16×2 LCD Module LCD1 - 1

Again we use ready made LCD Board for this purpose.

LCD Board for AVR PIC 8051
Fig. LCD Board

connect the LCD Board with development board with the help of single pin female to female wires as per the table given below.

Type LCD Board AVR Dev Board
Control Pins 1 R/W PB0
2 RS PB2
  3 LED PWM NOT CONNECTED
Power Pins 4 VCC 5V OUT (VCC)
5 GND GND
Data Pins 6 DB7 PD6
7 DB6 PD5
8 DB5 PD4
9 DB4 PD3
Control Pins 10 E PD7

Keypad

Schematic for keypad is shown below.

microwave keypad
Fig. Schematic of Keypad

This can be made by soldering push buttons on a general purpose PCB.

keypad for microwave
Fig. Keypad Prototype

 

Buzzer Interface

Buzzer interface consists of a 5v PCB mountable buzzer, a driving transistor and base resistor.

avr buzzer interface
Fig. Buzzer interface.

Bill of Materials

S. No. Item Reference Value Quantity
1 1/4 Resistor R1 4.7K ohms 1
2 Transistor Q1

BC547

1
3 5v Buzzer X1 - 1

Program


/*
 * MicrowaveController.c
 *
 * Created: 12/17/2013 6:01:36 PM
 *  Author: Avinash Gupta
 */


#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include <avr/interrupt.h>

#include "lib/lcd/lcd_hd44780_avr.h"
#include "lib/keypad/keypad.h"

#define MICRO_DDR DDRD
#define MICRO_PORT   PORTD
#define MICRO_POS PD0

#define GRILL_DDR DDRD
#define GRILL_PORT   PORTD
#define GRILL_POS PD1

#define BUZZER_DDR   DDRB
#define BUZZER_PORT  PORTB
#define BUZZER_POS   PB1

#define ON  1
#define OFF 0

#define TYPE_MICRO   1
#define TYPE_GRILL   2

void Init();
void SetMicro(uint8_t state);
void SetGrill(uint8_t state);

void SetTime();
void CountDown();

void SetBuzzer(uint8_t);
void Beep();

volatile uint8_t m=0;
volatile uint8_t s=0;
volatile uint8_t timer_running=0;

uint8_t type=TYPE_MICRO;

int main(void)
{
   Init();

   while(1)
   {
      LCDClear();

      LCDWriteFStringXY(3,0,PSTR("* Press *"));
      LCDWriteFStringXY(1,1,PSTR("Micro or Grill"));

      uint8_t k=GetKeypadCmd(1);

      switch(k)
      {
         case KEY_MICRO:
         {
            Beep();
            type=TYPE_MICRO;
            SetTime();
            timer_running=1;

            if(type==TYPE_MICRO)
               SetMicro(ON);
            else
               SetGrill(ON);

            CountDown();

            break;
         }
         case KEY_GRILL:
         {
            Beep();
            type=TYPE_GRILL;
            SetTime();
            timer_running=1;

            if(type==TYPE_MICRO)
               SetMicro(ON);
            else
               SetGrill(ON);

            CountDown();
            break;
         }
         case KEY_START:
         {
            Beep();
            //QUICK START
            type=TYPE_MICRO;
            if(!timer_running)
            {
               s=30;
               timer_running=1;
               SetMicro(ON);
               CountDown();
               break;
            }

         }
      }

   }
}
void Beep()
{
   SetBuzzer(ON);
   _delay_ms(25);
   SetBuzzer(OFF);
   _delay_ms(25);
}
void Init()
{
   //Set relay io lines as out put
   MICRO_DDR|=(1<<MICRO_POS); //Microwave relay
   GRILL_DDR|=(1<<GRILL_POS); //Grill relay


   //Set Buzzer line as output
   BUZZER_DDR|=(1<<BUZZER_POS);

   //Initialize LCD Module
   LCDInit(LS_NONE);

   //Initiallize keypad lib
   KeypadInit();

   //Init TIMER1 for main timer operation
   TCCR1B=(1<<WGM12)|(1<<CS12)|(1<<CS10); //CTC Mode prescaller 1024
   OCR1A=976;
   TIMSK|=(1<<OCIE1A);
}
ISR(TIMER1_COMPA_vect)
{
   if(!timer_running)
      return;

   if(s==0)
   {
      if(m==0)
      {
         //off
         timer_running=0;
      }
      else
      {
         m--;
         s=59;
      }
   }
   else
   {
      s--;
   }

}
void SetMicro(uint8_t state)
{
   if(state==ON)
   {
      MICRO_PORT|=(1<<MICRO_POS);
   }
   else
   {
      MICRO_PORT&=~(1<<MICRO_POS);
   }
}
void SetBuzzer(uint8_t state)
{
   if(state==ON)
   {
      BUZZER_PORT|=(1<<BUZZER_POS);
   }
   else
   {
      BUZZER_PORT&=~(1<<BUZZER_POS);
   }
}
void SetGrill(uint8_t state)
{
   if(state==ON)
   {
      GRILL_PORT|=(1<<GRILL_POS);
   }
   else
   {
      GRILL_PORT&=~(1<<GRILL_POS);
   }
}

void SetTime()
{
   uint8_t min=0;
   uint8_t sec=0;

   LCDClear();

   while(1)
   {
      if(type==TYPE_MICRO)
      {
         LCDWriteFStringXY(0,0,PSTR("MICRO"));
      }
      else
      {
         LCDWriteFStringXY(0,0,PSTR("GRILL"));
      }

      LCDWriteFStringXY(6,0,PSTR("MM:SS      "));

      LCDWriteIntXY(6,1,min,2);
      LCDWriteIntXY(9,1,sec,2);

      LCDWriteFStringXY(8,1,PSTR(":"));

      uint8_t key=GetKeypadCmd(1);

      switch(key)
      {
         case KEY_TS:
            if(min<90)
            {
               Beep();
               sec+=10;
               if(sec==60)
               {
                  sec=0;
                  min++;

                  if(min==91)
                  min=90;
               }

            }

            break;
         case KEY_M:
         {

            if(min<90)
            {
               min++;
               Beep();
            }
            break;
         }

         case KEY_TM:
         {
            if(min<90)
            {
               min+=10;
               if(min>=90)
               {
                  min=90;
                  sec=0;
               }
               else
                  Beep();
            }

            break;
         }

         case KEY_STOP:
            Beep();
            min=0;
            sec=0;
         break;

         case KEY_GRILL:
            Beep();
            type=TYPE_GRILL;
            break;

         case KEY_MICRO:
            Beep();
            type=TYPE_MICRO;
            break;

         case KEY_START:
         {
            if(min>0 || sec>0)
            {
               Beep();
               m=min;
               s=sec;
               return;

            }

         }

      }


   }
}

void CountDown()
{
   LCDClear();

   while(1)
   {
      uint8_t k=GetKeypadCmd(0);

      if(k==KEY_STOP)
      {
         //Pause
         timer_running=0;

         SetMicro(OFF);
         SetGrill(OFF);

         LCDWriteFStringXY(7,0,PSTR("PAUSED!"));
         LCDWriteFStringXY(6,1,PSTR("Press Start"));

         Beep();

         while(1)
         {
            k=GetKeypadCmd(1);

            if(k==KEY_START)
            {
               Beep();
               break;
            }
         }

         timer_running=1;

         if(type==TYPE_MICRO)
            SetMicro(ON);
         else
            SetGrill(ON);

         LCDClear();

      }
      else if(k==KEY_START)
      {
            if(m<=89)
            {
               if(s<30)
               {
                  s+=30;
                  if(s>=60)
                  {
                     m++;
                     s=s-60;

                  }
                  Beep();

               }

            }
      }

      if(m==0 && s==0)
      {
         LCDClear();
         LCDWriteFStringXY(0,5,PSTR("Ready !"));



         SetMicro(OFF);
         SetGrill(OFF);

         //Alert
         for(uint8_t i=0;i<4;i++)
         {
            SetBuzzer(ON);
            _delay_ms(500);
            SetBuzzer(OFF);
            _delay_ms(500);
         }

         GetKeypadCmd(1);

         Beep();

         return;
      }
      LCDWriteIntXY(0,1,m,2);
      if(s%2)
      {
         LCDWriteStringXY(2,1,":");
      }
      else
      {
         LCDWriteStringXY(2,1," ");
      }

      LCDWriteIntXY(3,1,s,2);

      if(type==TYPE_MICRO)
      {
         LCDWriteFStringXY(0,0,PSTR("MICRO"));
      }
      else
      {
         LCDWriteFStringXY(0,0,PSTR("GRILL"));
      }
   }

}

Downloads

By
Avinash Gupta

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15 thoughts on “Microwave Controller using ATmega8 – AVR Project

  • By Az Robot Indonesia - Reply

    This is Amazing Project :D

    I will wait next of porject..

  • By RAKESH KUMAR PAL - Reply

    SIR

    PL SENT FULL DETAIL AND COST

  • By leela - Reply

    hi sir,

    I had seen the project”Microwave Controller using ATmega8 – AVR Project”,its very nice.i would like to by the project can you send the cost details of the project as soon as possible
    thankyou

  • By mohammad - Reply

    thanks you my avr weak

  • By uttam - Reply

    how to compile microwave-controller-using-atmega8-
    AVR studio but hex file not create

  • By Navin Datt - Reply

    Sir,
    I use AVR Studio 4 & ‘eXtreeme burner” software, (with USB AVR Programer, obtained from ‘eXtreeme electronics’) to burn the chip, so can I use the same set-up for this project? Are the libraries used in this project, present in AVR Studio 4 ? Pl. give a hint…
    Thanx & Regards….

  • By nurul - Reply

    how to connect relay,, wheres the ready connection for micro and grill relay? :o

  • By mani - Reply

    I cant find those two file included in the program from library lcd.can u please post that files

  • By saumnen - Reply

    I cant find file “lib/keypad/keypad.h” which one is included in the program .can u please post that files

  • By Pinaki Ghosh - Reply

    I cant find two files
    “lib/lcd/lcd_hd44780_avr.h”
    “lib/keypad/keypad.h”
    can u please post this 2 files.i like this project very much.please post, its urgent for my final year project.

  • By mAx - Reply

    Hi
    Very good job!
    but can you share the file of library: keypad and lcd_hd44780_avr?

    Regards mAx

  • By saumen - Reply

    unable to download the source code,pls help me

    • By Avinash - Reply

      @saumen

      Only customers and loyal readers are allowed to download.

  • By Dinesh - Reply

    great project. Can u please send the fuse bit to burn .hex file

    thanks

  • By imam - Reply

    Sir, how to add a door switch function fo safety?.
    thank you for this great article.

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