ELEC3300_06_stu

ELEC3300_06_stu - ELEC 3300 Microprocessor Applications...

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ELEC 3300 : Fall 11/12 Tim Woo 1 ELEC 3300 Microprocessor Applications Topic 6 Interrupt Organization Interrupt Organization Prof. Tim Woo Prof. Tim Woo
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ELEC 3300 : Fall 11/12 Tim Woo 2 Where we are Timer and Counter Basic Computer Structure Introduction to Microprocessor-based Systems Digital and Analog Interfacing Interrupt Organization Memory, Interfacing to Memory, Memory Timing and applications Motor Interfacing Buffering and Direct Memory Access (DMA) Interfacing LCD Other Serial Bus Interface: IEEE1394, USB, I2C and SPI Serial Communication and RS-232 Standard To be covered In progress Done Microcontroller Structure A/D Port Assembler Instruction Set Architecture Memory I/O System CPU Serial Port External Memory Port Interrupt Port Simple Port In this course, 8051 is used as a driving vehicle for delivering the concepts.
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ELEC 3300 : Fall 11/12 Tim Woo 3 • On successful completion of this topic, you will be able to – Compare polling I/O with interrupt-driven I/O – Understand the timing diagram of interrupt service routine – Evaluate several issues deal with • Identification of which device caused the interrupt • Nested and simultaneous interrupts – Understand the interrupt organization in 8051micro-controller Expected Outcomes Expected Outcomes
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ELEC 3300 : Fall 11/12 Tim Woo 4 Polled I/O requires the CPU to ask a device if the device requires servicing – For example, if the devices have changed status – Software polls the devices to know when a device will be serviced Polling Polling Polling requires code to loop until the device is ready – Consumes a lot of CPU cycles – Have a guaranteed delay but some applications do not have a predictable delay (e.g. In loading a printer buffer with text, the buffer can run out before the printer is polled again and thus printing stops)
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ELEC 3300 : Fall 11/12 Tim Woo 5 Interrupt I/O allows the device to interrupt the CPU announcing that the device requires attention – This allows CPU to ignore devices unless they request servicing via interrupt – Software does not know when an interrupt will occur, and this makes it more difficult to write code Interrupts do not require code to loop until the device is ready – Device interrupts CPU when it needs attention – Code can go off to do other things Interrupts Interrupts INT1 8051
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ELEC 3300 : Fall 11/12 Tim Woo 6 Before an I nterrupt S ervice R outine ( ISR ) can do anything, it must save away the current program’s registers (if it touches those registers) Timing diagram of Interrupts Timing diagram of Interrupts
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This note was uploaded on 10/16/2011 for the course ELEC 308,315,10 taught by Professor Prof.shenghuisong during the Spring '11 term at CUHK.

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ELEC3300_06_stu - ELEC 3300 Microprocessor Applications...

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