Hardware manual

Microcomputer Technical Q&A

Q&A No.: QAH8S-211

Category: DMAC

Subject: Handling of Transfer End Interrupt

Questions

The manual states that if DTE is cleared to 0 when DTIE = 1, an interrupt request is sent to the

CPU.

1. In the case shown in the figure, will DMA transfer end interrupts be generated continually?

2. How can interrupt generation be prevented?

DMA interrupt handling

DTE = 0, DTIE = 1

values held

RTE

Answers

1. In the case in the figure, interrupts will be generated continually.

2. An interrupt will always be generated if DTIE is set to 1 (enabling interrupts) when DTE = 0.

Therefore, either set the DTE bit to 1 (the BSET instruction can be used) or clear the DTIE bit

to 0 (the BCLR instruction can be used).