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Teachers Name : Suman Sarker Telecommunication Technology
Subject Name : Microcontroller & Embedded SystemSubject Code : 6871Semester :7th
Department : Electronics
Ideal Institute Of Science & Technology (IIST)
LECTURE-10 CH-11
INTERRUPT OF 8051
What is Interrupt?
What is Interrupt?
What is Interrupt?
What is Interrupt?
What is Interrupt?
InterruptReading Remember Open Return to work
What is Interrupt?
InterruptProcessing
Remember current instruction address in Stack Register
ExecuteISR
Return to work
In terms of MCU
Types of Interrupt
External / Hardware Interrupt Internal / Software Interrupt
Physical or interrupt from outside ADC, TIMER, USART etc.
External Interrupt
PIC 16F877A has the following 15 interrupt sources :1)External2)Timer 03)Timer 14)RB Port Change5)Parallel Slave Port Read/Write6)A/D Converter7)USART Receive8)USART Transmit9)Synchronous Serial Port10)CCP1 (Capture, Compare, PWM)11)CCP2 (Capture, Compare, PWM)12)TMR2 to PR2 Match13)Comparator14)EEPROM Write Operation15)Bus Collision
The 5 registers that used to control the operation of Interrupts in PIC 16F877A Microcontroller :1)INTCON2)PIE13)PIR14)PIE25)PIR2
INTCON Register
INTCON Register PIC 16F877A
INTCON Register is a readable and writeable register which contains various enable and flag bits for External and Internal Interrupts.
GIE – Global Interrupt Enable
1– Enables all unmasked interrupts0 – Disables all interrupts
PEIE – Peripheral Interrupt Enable1 – Enables all unmasked peripheral interrupts0 – Disables all peripheral interrupts
TMR0IE – Timer 0 Overflow Interrupt Enable1–Enables the TMR0 interrupt0 – Disables the TMR0 interrupt
INTE – RB0/INT External Interrupt Enable1 – Enables the RB0/INT external interrupt0 – Disables the RB0/INT external interrupt
RBIE – RB Port Change Interrupt Enable1 – Enables the RB port change interrupt0 – Disables the RB port change interrupt
TMR0IF – Timer 0 Overflow Interrupt Flag1 – TMR0 register has overflowed. It must be cleared in software.0 – TMR0 register did not overflow
INTF – RB0/INT External Interrupt Flag1 – The RB0/INT external interrupt occurred. It must be cleared in software.0 – The RB0/INT external interrupt did not occur
RBIF – RB Port Change Interrupt Flag1 – At least one of the RB7 – RB4 pins changed state, a mismatch condition will continue to setthe bit. Reading PORTB will end the mismatch condition and allow the bit to be cleared. It must be cleared in software.0 – None of the RB7 – RB4 pins have changed state
INTEDG bit of OPTION_REG Register is the Interrupt Edge Select bit. When it is 1 interrupt is on rising edge of RB0/INT pin and when it is 0 interrupt is on falling edge of RB0/INT pin.
External Interrupt
Next Lecture
LCD AND KEY BOARD INTERFACING
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