interrupts - CSE 380 Interrupts Overview Interrupt Sources...

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CSE 380 Interrupts Overview Interrupt Sources 21 Generated by Internal Function Blocks External Pins Interrupt Types Fast Normal Interrupt Sources Selected Individual Interrupt Sources User Interrupt (Momentary Switch) Bit 0 UART0 Transmit Bit 4 Bit 5 UART1 Transmit Bit 6 Bit 7 Timer 0 Bit 10 Timer 1 Bit 11 Interrupt Registers Interrupt Mode Register Addresses INTMOD 0x3FF4000 Function Specifies fast (FIQ) or normal (IRQ) interrupts FIQ = 1 IRQ = 0 Interrupt Pending Register Addresses INTPND 0x3FF4004 Unused Interrupt Mode Bits 0 31 21 20 Unused Interrupt Pending Bits 0 31 21 20
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Function Specifies whether an interrupt source is pending Pending = 1 Not Pending = 0 Must be cleared at top of service routine Interrupt Mask Register Addresses INTMSK 0x3FF4008 Function Individual Interrupt Masks Specifies whether the individual interrupt is handled by the CPU Serviced = 0 Not Serviced = 1 Global Mask Bit (G) Enable Interrupt Service Requests = 0 Disable Interrupt Service Requests = 1 Interrupt Priority Register Interrupt index value is written to appropriate position to set the priority Index is the same as the bit position in the MODE, MASK, and PENDING registers Interrupt Servicing Interrupted instruction is NOT executed LR loaded with instruction AFTER interrupted instruction After interrupt is serviced, return to interrupted instruction! SUB PC, LR, #4
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interrupts - CSE 380 Interrupts Overview Interrupt Sources...

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