| 摘要 |
PROBLEM TO BE SOLVED: To provide a DMA control method and a DMA controller for preventing access to a memory area for another channel. SOLUTION: The start address SA and terminal address EA of a memory area to be used are set in each channel, and when DMA transfer starts, and an access address reaches a terminal address EA, the access address is returned to the start address SA, and access is continued. Memory access is performable only between the start address SA and the terminal address EA set in each channel. In attaching data for three pages to a first channel, when a memory area runs short in the attachment of the third page ((a), (b)), the same transfer frequency as that for the DMA transfer of the first page and the second page is set for the DMA transfer of the third page. In this case, when the access address reaches the terminal address EA, the access address is automatically returned to the start address SA, and access is continued ((c)) so that the second channel can be prevented from being accessed. COPYRIGHT: (C)2007,JPO&INPIT |
