Interrupts

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Why use interrupts? • As programs (or systems) grow it becomes very difficult to predict/ensure that time-critical events are handled properly – Example: • An external device sends data to the processor • The processor must read the data before that data is overwritten – This is typical in serial data transmission 1/4/2010 4
Maskable/Non-maskable • <strong>Interrupts</strong> in general can be divided into two kinds- maskable and non-maskable. – A maskable interrupt is an interrupt whose trigger event is not always important: • The program can decide if the event should be recognized or ignored and can be disabled/enabled – A non-maskable interrupt is so important that it should never be ignored • The processor will always jump to this interrupt when it happens • The reset button is an example 1/4/2010 5
Page 1 and 2: Microprocessor Fundamentals Topic 1
Page 3: Interrupts • Interrupts are async
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 and 22: An Example: • So, let’s work th
Page 23 and 24: An Example: We must start our progr
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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