Under what circumstances can the MCS-51 microcontroller respond to an interrupt? What is the interrupt response process?-EEWORLD

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Under what circumstances can MCS-51 respond to interrupts? What is the process of interrupt response?

A: Conditions for responding to interruptions

(1) The interrupt source has an interrupt request;

(2) The interrupt enable bit EA = 1;

(3) The interrupt enable bit of the interrupt source requesting the interrupt is 1;

On the basis of meeting the above conditions, if any of the following situations exists, the interrupt response will be blocked.

(1) The CPU is executing an interrupt service routine of the same or higher priority.

(2) The instruction being executed has not yet been completed.

(3) The interrupt return instruction RETI or the instruction to read/write the special registers IE and IP is being executed. After executing the above instructions, the CPU needs to execute another instruction to respond to the interrupt request.

After the interrupt request is responded to, an internal long call (LCALL) redirects the program to the corresponding interrupt vector address and executes the interrupt service routine.

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