This document describes the components and software used in a microwave oven embedded system project. It includes a microcontroller, matrix keypad, 7-segment display, cooler fan, digital keyboard, LEDs, relay, reset button, buzzer, heater, LCD, and potentiometer. The document discusses how these components are interfaced with the microcontroller and the software programs used, including a host PC, target PIC microcontroller, and MPLAB X IDE compiler. It also provides details on programming concepts like interrupts, timers, triggering methods, and interfacing the keypad, LEDs, LCD, and other components with the microcontroller.

1. MICROWAVE OVEN
by
BOOMIKA D
BANNARI AMMAN INSTITUTE
OF TECHNOLOGY

2. EMBEDDED SYSTEM
 An embedded system is a microprocessor or
microcontroller based computer hardware system
with software that is designed to perform a dedicated
function.
Example:
 Mobile phone
 Microwave oven
 GPS system

3. IMPORTANT SOFTWARE
❏ HOST - PC
❏ TARGET - PICSIMLAB
❏ CROSS COMPILER - MPLAB X IDE

4. COMPONENTS
 Microcontroller (PIC16F877A)
 Matrix keypad
 7 segment display
 Cooler fan
 Digital keyboard
 LED
 Relay
 Reset button
 Buzzer
 Heater
 LCD
 Potentiometer

5. LIGHT EMITTING DIODE (LED)
 Semiconductor device
 Mostly used for indication purposes
 LEDs are connected to PORTB and PORTD
 TRIS stands for Tri-State
 TRISB register is important for I/O configuration
 Logic 1 = Input (Sinking Circuit)
 Logic 0 = Output (Sourcing Circuit)

6. CHARACTER LIQUID CRYSTAL
DISPLAY(CLCD)
 Print all the ASCII values and few special
symbols
 16 interfacing line
 Modes
 4 bit mode
 8 bit mode

7. PORT D = OUTPUT
RE2(RS) = OUTPUT
RE1(E) = OUTPUT
 INSTRUCTION (RS) = 0
 DATA (RS) = 1
 READ (R/W) = 1
 WRITE (R/W) = 0

8. TRIGGERING METHOD
 Level Trigger - Latches
 Edge Trigger - Flip flop

9. MATRIX KEYPAD
 Mostly used in telephones, calculators, digital lockers, and
a variety of other applications.
COLUMNS : Input = PORTB (RB0, RB1, RB2)
ROWS : Output = PORTD (RD0 to RD3)

10. POLLING METHOD
 Continuously monitoring something
 Disadvantages:
 Bad response time
 Loss of event
 Bad power management

11. INTERRUPTS
 Disturbance or signal from the hardware device.
 Communication set up in a microprocessor or
microcontroller
❏ An internal or external device requests the MPU
to stop the processing
❏ The MPU acknowledges the request
❏ Attends to the request
❏ Goes back to processing where it was interrupted
.

12. CLASSIFICATION OF INTERRUPTS

13. TIMERS
RESOLUTION (Register Width) :
 TIMER = 8 bit (0 to 255)
 TIMER = 16 bit (0 to 65535)
TICK (total tick = 255) :
 Up Count = 0 1 2 . . . . . . . . 255
 Down Count = 255 244 243 . . . . . . . . . .0
QUANTUM :
 Quantum is measure of time which is responsible for tick.
 Depending on the system clock settings
 Tick is based on instruction cycle (IC)
1 IC time = 200 n sec = quantum

14. SCALE AND MODES
SCALE
1:1 = tick increment after 1 IC => 200nsec
PRE SCALING
1:2 = tick increment after 2 IC => 400nsec
1:4 = tick increment after 4 IC => 800nsec
1:1 = 1 overflow go to isr => 51.2usec
POST SCALING
1:2 = after 2 overflow go to isr => 102.4usec
1:4 = after 4 overflow go to isr => 204.8usec
MODES
 Counter
 PWM or Pulse Generator
 PW or PP Measurement

15. THANK YOU