HD64570 Datasheet, PDF (318/469 Pages) Hitachi Semiconductor – Serial Communications Adaptor

6.7 Precautions
• The DMAC registers must be initialized in DMA initial state. When DMAC operation is
suspended by software with the DE bit set to 0, the DMAC retains its previous operation
status. Thus, to initiate a new operation, the software abort command must be issued to
initialize the status. However, when DMAC operation is terminated with transfer completion
conditions satisfied, the software abort command is not necessary. For details, see section
6.2.11, DMA Command Register (DCR).
• The DMAC must be disabled in system stop mode.
Rev. 0, 07/98, page 302 of 453