HD6417751 Datasheet, PDF (565/1105 Pages) Renesas Technology Corp – SuperH RISC engine

14.5.3 Transfer Request Acceptance on Each Channel
On channel 0, a DMA data transfer request can be made by means of the DTR format. No further
transfer requests are accepted between DTR format acceptance and the end of the data transfer.
On channels 1 to 3, output a transfer request from an external device by means of the DTR format
(ID = 01, 10, or 11) after making DMAC control register settings in the same way as in normal
DMA mode. Each of channels 1 to 3 has a request queue that can accept up to four transfer
requests. When a request queue is full, the fifth and subsequent transfer requests will be ignored,
and so transfer requests must not be output. When CHCR.TE = 1 when a transfer request remains
in the request queue and a transfer is completed, the request queue retains it. When another
transfer request is sent at that time, the transfer request is added to the request queue if the request
queue is vacant.
Rev. 3.0, 04/02, page 525 of 1064