Lecture7-part1-4pg - Reading Assignment EEL 4744C Microprocessor Applications M&M Chapter 8 Or Software and Hardware Engineering(new version

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1 Dr. Tao Li 1 EEL 4744C: Microprocessor Applications Lecture 7 Part 1 Interrupt Dr. Tao Li 2 Or Software and Hardware Engineering (new version): Chapter 12 Reading Assignment Dr. Tao Li 3 An interrupt is an important asynchronous event that needs to be recognized and dealt with by the CPU that is executing instructions in a program You can keep polling the external devices, e.g. sensors, detectors, etc. But doing this periodically takes time away from your system and reduce overall performance Use interrupts! Your external sensor, when it detects something peculiar, generates a signal called interrupt request, i.e. IRQ Interrupt Dr. Tao Li 4 An interrupt is an important asynchronous event that needs to be recognized and dealt with by the CPU that is executing instructions in a program You can keep polling the external devices, e.g. sensors, detectors, etc. But doing this periodically takes time away from your system and reduce overall performance Use interrupts! Your external sensor, when it detects something peculiar, generates a signal called interrupt request, i.e. IRQ Interrupt
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2 Dr. Tao Li 5 The IRQ is asynchronous, i.e. the time it happens has no relation to the instructions being executed by the CPU The IRQ requires an ISR, or interrupt service routine, to be executed immediately. The ISR should be part of the running program Interrupts can also be used to synchronize a real-time system to control exactly when things are performed by the system, e.g. A/D IRQ to CPU signaling completion of A-to-D conversion Interrupt Dr. Tao Li 6 Allow for asynchronous events to occur and be recognized Wait for the current instruction to finish before taking care of any interrupt Branch to the correct ISR to service the external device that issued the IRQ Return to the interrupted program where it was interrupted Allow for a variety of interrupting signals, including signal levels and edges (rising/falling)
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This note was uploaded on 11/13/2011 for the course EEL 4744c taught by Professor Staff during the Fall '09 term at University of Florida.

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Lecture7-part1-4pg - Reading Assignment EEL 4744C Microprocessor Applications M&M Chapter 8 Or Software and Hardware Engineering(new version

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