Motorola MSC8101 ADS User's Guide Page 135

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MSC8101 User’s Guide 7-1
Chapter 7
Interrupts and Interrupt Priorities
This chapter describes a step-by-step procedure for handling MSC8101 interrupts. The
main steps in this procedure are the software configuration phases for setting up the
information in the interrupt controller registers and the interrupt subroutines to be
executed. An example driver implementation illustrates both the hardware and software
configurations for connecting to a peripheral (the EFCOP) and interrupting it. Refer to the
MSC8101 Reference Manual for information on features not implemented by the driver.
7.1 Interrupt Basics
The MSC8101 interrupt scheme consists of three different interrupt controllers:
Programmable interrupt controller (PIC), which operates in the SC140 core. The
PIC receives interrupts from DSP peripherals, DMA, external
IRQ[2–3], and the SIC.
When the PIC detects an interrupt request (
IRQ) on one or more of its inputs, it
arbitrates each IR according to its priority level.
SIU-CPM interrupt controller (SIC), which generates interrupt requests to the PIC.
The SIC receives interrupts from internal sources, such as the Periodic Interrupt
Timer (PIT) or Time Counter Register (TMCNT), from the CPM, and from
external sources such as port C parallel I/O pins or IRQs. The SIC generates
interrupt requests to the PIC to be handled by the SC140 core.
External SIU-CPM interrupt controller (SIC_EXT), which generates interrupt
requests to an external host CPU. The SIC_EXT receives interrupts from the same
sources as the SIC with additional
IRQs from external IRQ[2–3] and DMA, but it
generates interrupts externally for handling by an external processor. The use of
two SICs increases flexibility since each SIC can handle different interrupt sources.
For example, the SC140 core can handle DSP-related interrupts while another
processor, such as the MSC8101 device or the PowerQUICC II, handles
communication-related interrupts.
This configuration provides maximum flexibility so that interrupts can be handled
internally by the SC140 core, by an external host, or by a combination of the two. Figure
7-1 shows the MSC8101 interrupt structure.
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