Interrupts

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An Example: • So, let’s work through an example: 1/4/2010 – Assume we have a switch attached to PD0 that will cause a high-to-low transition – We want the signal to interrupt the processor and execute our ISR • So, we must write a initialization routine that will allow this interrupt to occur Exercise: What must the first two instructions be for our program? 22
An Example: We must start our program with at least the first two instructions (I included all of the external interrupt vectors so this can be used as a template). 1/4/2010 $0000 jmp RESET ; Reset Handler $0002 jmp EXT_INT0 ; IRQ0 Handler $0004 jmp EXT_INT1 ; IRQ1 Handler $0006 jmp EXT_INT2 ; IRQ2 Handler $0008 jmp EXT_INT3 ; IRQ3 Handler $000A jmp EXT_INT4 ; IRQ4 Handler $000C jmp EXT_INT5 ; IRQ5 Handler $000E jmp EXT_INT6 ; IRQ6 Handler $0010 jmp EXT_INT7 ; IRQ7 Handler 23
Page 1 and 2: Microprocessor Fundamentals Topic 1
Page 3 and 4: Interrupts • Interrupts are async
Page 5 and 6: Maskable/Non-maskable • Interrupt
Page 7 and 8: EICRA INT3 - 0 • External Interru
Page 9 and 10: EICRA INT3 - 0 1/4/2010 Exercise: W
Page 11 and 12: Pins • INT3:0 External Interrupts
Page 13 and 14: Pins • INT3:0 When the appropriat
Page 15 and 16: Pins • INT3:0 Exercise: I want to
Page 17 and 18: Pins • Bits 7 - 4 External Interr
Page 19 and 20: Vectors The complete vector table i
Page 21: An Example: • So, let’s work th
Page 25 and 26: An Example: We need to write the in
Page 27 and 28: An Example: We must start our progr
Page 29 and 30: An Example: Then we must write the
Page 31 and 32: What happens? • So what happens w
Page 33: Summary • In this topic we: - Bec

Interrupts

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