interrupts in 8051

 interrupts in 8051 implimentation

____________________________________________________________________________________________________

  • What is interrupt ? – An interrupt is an external or internal event that interrupts the microcontroller to inform it that a device needs its service.
  • Why we need interrupt? – A single microcontroller can serve several devices by two ways
  1. Interrupt-Whenever any device needs its service, the device notifies the microcontroller by sending it an interrupt signal. Upon receiving an interrupt signal, the microcontroller interrupts whatever it is doing and serves the device. The program which is associated with the interrupt is called the interrupt service routine (ISR) or interrupt handler
  2. Polling- The microcontroller continuously monitors the status of a given device. When the conditions met, it performs the service. After that, it moves on to monitor the next device until every one is serviced
  • Advantage of interrupt– The polling method is not efficient, since it wastes much of the microcontroller’s time by polling devices that do not need service. The advantage of interrupts is that the microcontroller can serve many devices, Each devices can get the attention of the microcontroller based on the assigned priority . For the polling method, it is not possible to assign priority since it checks all devices in a round-robin fashion.

routine of interrupts in 8051

  • How does interrupt works?
    •  Whenever any device needs its service, the device notifies the  microcontroller by sending it an interrupt signal.
    •  Upon receiving an interrupt signal, the microcontroller interrupts whatever it is doing and saves the address of the next instruction (PC) on the stack pointer (SP).
    • It jumps to a fixed location in memory, called the interrupt vector table, that holds the address of the ISR(interrupt service routine). Each interrupt has its own ISR.  The microcontroller gets the address of the ISR from the interrupt vector table and jumps to it
    • It starts to execute the interrupt service subroutine until it reaches the last instruction of the subroutine which is RETI (return from interrupt).RETI not used in C coding.
    • Upon executing the RETI instruction, the microcontroller returns to the place where it was interrupted and First, it gets the program counter (PC) address from the stack pointer by popping the top two bytes of the stack into the PC
    • Then it starts to execute from that address and continue what it executing before.
    • This whole process is shown graphically in above pics.

interrupts of 8051

  • Interrupt vector table –Interrupt vector table shows priority of different interrupts. As below table shown,Reset has highest priority among all interrupt and serial COM(USART) has lowest. Priority is high to low as Reset to serial COM. Upon Reset, all interrupts are disabled (masked), meaning that none will be responded to by the microcontroller if they are activated. There are 6 total interrupts in 8051 microcontroller. First is Reset, two hardware external interrupt INT0 and INT1, two Timer interrupt TF0 and TF1 and last one is serial com interrupt that is for both receiver and transmitter.
no Interrupt ROM address Pin
1 Reset 0000 9
2 External HW (INT0) 0003 P3.2 (12)
3 Timer 0 (TF0) 000B
4 External HW (INT1) 0013 P3.3 (13)
5 Timer 1 (TF1) 001B
6 Serial COM (RI and TI) 0023
 
  • Applications – To provide services to the devices efficiently.

Click Here : understanding of RESET interrupt

Click Here : understanding of  External interrupt INT0 & INT1 

Click Here : understanding of Timer interrupt TF0 & TF1

Click Here : understanding of Serial interrupt

1. circuit diagram of  external interrupts in 8051 microcontroller

interrupt ____________________________________________________________________________________________________

2. circuit diagram of serial communication interrupts in 8051

SERIALCOMMUNICATION INTERRUPT OF 8051 ____________________________________________________________________________________________________

3. circuit diagram of 8051 with led in which blinking of led is due to timer 0 interrupt

Untitled

1. Program Of external interrupts of 8051 , In Which Interrupt 0 control 7 Segment And Interrupt 1 Control LCD Display

PROTEUS File for SIMULATION(Password Of RAR file is :-firmcodes.com)

download (1) ____________________________________________________________________________________________________

2.  PROGRAM OF SERIAL COMMUNICATION  INTERRUPT IN WHICH DATA SEND FROM PC OR LAPTOP IS DISPLAYED ON LCD 

PROTEUS File for SIMULATION(Password Of RAR file is :-firmcodes.com)

download (1) ____________________________________________________________________________________________________

3. PROGRAM OF TIMER 0 INTERRUPT IN WHICH LED BLINKING  IS CONTROLLED

 

PROTEUS File for SIMULATION(Password Of RAR file is :-firmcodes.com)

download (1) ____________________________________________________________________________________________________  

Content for the tab VIDEO