Hardware manual

Microcomputer Technical Q&A
79
Q&A No.: QAH8S-207
Category: DMAC
Subject: Handling of Transfer Request before Start of Transfer
Question
If a transfer request is generated before the DMAC starts transfer, is the request ignored?
Answer
• If the activation source is an internal interrupt
If the DTE bit is 0, a CPU interrupt is requested. When the DTE bit is set to 1 while that
interrupt is masked by the CPU, an activation request is sent to the DMAC.
• If the activation source is an external request
When edge-sensing is selected, the first activation after enabling is performed on detection of a
low level, and therefore the request will not be ignored if the low level is held.
Applicable Products
Applicability Series Applicability Series Applicability Series
Entire H8S Series Yes H8S/2655 Yes H8S/2350
H8S/2355 Yes H8S/2357 H8S/2345
H8S/2245 H8S/2148 H8S/2144
H8S/2138 H8S/2134 H8S/2128
H8S/2124 — — — —