9
9-2
DMAC
32180 Group User’s Manual (Rev.1.0)
9.1 Outline of the DMAC
The microcomputer internally contains a 10-channel DMAC (Direction Memory Access Controller). It allows data
to be transferred at high speed between internal peripheral I/Os, between internal RAM and internal peripheral I/O,
or between internal RAMs, as initiated by a software trigger or requested from an internal peripheral I/O.
Table 9.1.1 Outline of the DMAC
Item Description
Number of channels 10 channels
Transfer request sources • Software trigger
• Request from internal peripheral I/Os: A-D converter, multijunction timer, serial I/O (reception
completed, transmit buffer empty) or CAN
• DMA channels can be cascaded (Note 1)
Maximum number of 65,536 times
times transferred
Transferable address • 64 Kbytes (address space from H’0080 0000 to H’0080 FFFF)
space • Transfers between internal peripheral I/Os, between internal RAM and internal peripheral I/O, and
between internal RAMs are supported.
Transfer data size 16 or 8 bits
Transfer method Single transfer DMA (control of the internal bus is relinquished for each transfer performed), dual-
address transfer
Transfer mode Single transfer mode
Direction of transfer One of three modes can be selected for the source and destination:
• Address fixed
• Address incremental
• Ring buffered
Channel priority DMA0 > DMA1 > DMA2 > DMA3 > DMA4 > DMA5 > DMA6 > DMA7 > DMA8 > DMA9
(Priority is fixed)
Maximum transfer rate 13.3 Mbytes per second (when internal peripheral clock BCLK = 20 MHz)
Interrupt request Group interrupt request can be generated when each transfer count register underflows.
Transfer area 64 Kbytes from H’0080 0000 to H’0080 FFFF (Transferable in the entire RAM/SFR area)
Note 1: The DMA channels can be cascaded in the manner described below.
• Start DMA transfer on DMA1 upon completion of one DMA transfer on DMA0
• Start DMA transfer on DMA5 upon completion of all DMA transfers on DMA0 (upon underflow of the transfer count
register)
• Start DMA transfer on DMA2 upon completion of one DMA transfer on DMA1
• Start DMA transfer on DMA0 upon completion of one DMA transfer on DMA2
• Start DMA transfer on DMA3 upon completion of one DMA transfer on DMA2
• Start DMA transfer on DMA4 upon completion of one DMA transfer on DMA3
• Start DMA transfer on DMA6 upon completion of one DMA transfer on DMA5
• Start DMA transfer on DMA7 upon completion of one DMA transfer on DMA6
• Start DMA transfer on DMA5 upon completion of one DMA transfer on DMA7
• Start DMA transfer on DMA8 upon completion of one DMA transfer on DMA7
• Start DMA transfer on DMA9 upon completion of one DMA transfer on DMA8
9.1 Outline of the DMAC
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