Usage Notes; Dmac Register Access During Operation - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

Enabling or disabling of each interrupt source is set by means of the DTIE bit in DMABCRL for
the corresponding channel in DMABCRL, and interrupts from each source are sent to the interrupt
controller independently. The priority of transfer end interrupts on each channel is decided by the
interrupt controller, as shown in table 7.12.
Figure 7.38 shows a block diagram of a transfer end/transfer break interrupt. An interrupt is
always generated when the DTIE bit is set to 1 while the DTE bit in DMABCRL is cleared to 0.
DTE/
DTME
DTIE
Figure 7.38 Block Diagram of Transfer End/Transfer Break Interrupt
In full address mode, a transfer break interrupt is generated when the DTME bit is cleared to 0
while the DTIEB bit is set to 1. In both short address mode and full address mode, DMABCR
should be set so as to prevent the occurrence of a combination that constitutes a condition for
interrupt generation during setting.
7.7

Usage Notes

7.7.1

DMAC Register Access during Operation

Except for forced termination of the DMAC, the operating (including transfer waiting state)
channel setting should not be changed. The operating channel setting should only be changed
when transfer is disabled. Also, DMAC registers should not be written to in a DMA transfer.
DMAC register reads during operation (including the transfer waiting state) are described below.
• DMAC control starts one cycle before the bus cycle, with output of the internal address.
Consequently, MAR is updated in the bus cycle before DMA transfer. Figure 7.39 shows an
example of the update timing for DMAC registers in dual address transfer mode.
Rev. 1.0, 09/01, page 312 of 904
Transfer end/transfer
break interrupt