M32CSLASH8B datasheet(115/406 Pages) RENESAS

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M32C/8B Group

11. Interrupts

Preliminary specification

Specifications in this manual are tentative and subject to change.

REJ09B0450-0050 Rev.0.50 Oct 31, 2008

Page 98 of 385

11.4

High-Speed Interrupt

The high-speed interrupt executes an interrupt sequence in five cycles and returns from the interrupt routine in

three cycles. When the FSIT bit in the RLVL register is set to 1 (interrupt priority level 7 is used for the high-

speed interrupt), the interrupt that bits ILVL2 to ILVL0 in the Interrupt Control Register are set to 111b (level 7)

becomes the high-speed interrupt.

Only one interrupt can be set as the high-speed interrupt. To use the high-speed interrupt, do not set multiple

interrupts to interrupt priority level 7. Set the DMAII bit in the RLVL register to 0 (interrupt priority level 7 is

used for interrupt) to use the high-speed interrupt.

Set the starting address of a high-speed interrupt routine in the VCT register.

When the high-speed interrupt is acknowledged, the FLG register value is saved into the SVF register and the

PC value is saved into the SVP register. A program is executed from an address indicated by the VCT register.

Use the FREIT instruction to return from a high-speed interrupt routine. Values saved into registers SVF and

SVP are restored to the FLG register and PC by executing the FREIT instruction.

The high-speed interrupt, and DMA2 and DMA3 share some of the registers. When using the high-speed

interrupt, neither DMA2 nor DMA3 is available. DMA0 and DMA1 can still be used.

Figure 11.2 shows a procedure to use high-speed interrupt.

Figure 11.2

Procedure to Use High-Speed Interrupt

I flag = 0

RLVL register: FSIT bit = 1

DMAII bit = 0

I flag = 1

Operate peripheral functions

VCT regsiter: Set the starting address of

the high-speed interrupt routine

Interrupt Control Register:

Bits ILVL2 to ILVL0 = 111b (level 7)

Interrupt enabled

Interrupt disabled

Interrupt priority level 7 is used for the high-speed interrupt

Interrupt priority level 7 is used for interrupt

Set the interrupt priority level in the Interrupt Control Register

for the peripheral function used for the high-speed

interrupt source.

Set the peripheral function used for the high-speed

interrupt source

Start

End

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