Interrupts
2-21
Architectural Overview
2.8
Interrupts
The ’C3x supports four external interrupts (INT3–INT0), a number of internal
interrupts, and a nonmaskable external RESET signal. These can be used to
interrupt either the DMA or the CPU. When the CPU responds to the interrupt,
the IACK pin can be used to signal an external interrupt acknowledge. Section
7.5,
Reset Operation, on page 7-21 covers RESET and interrupt processing.
The ’C30 and ’C31 external interrupts are level-triggered. To reduce external
logic and simplify the interface, the ’C32 external interrupts are edge- and level-
or level-only triggered. The triggering is user-selectable through a bit in the
status register. See Section 3.1.7,
Status Register (ST), for more information.
Two external I/O flags, XF0 and XF1, can be configured as input or output pins
under software control. These pins are also used by the interlocked operations
of the ’C3x. The interlocked-operations instruction group supports multiproces-
sor communication. See Section 7.4,
Interlocked Operations, on page 7-13 for
examples.