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CHAPTER 15 DMAC
15.1 Overview of DMAC
The DMAC is a built-in module of the MB91F109 that implements direct memory access
(DMA).
■
DMAC Characteristics
• Eight channels
• Three modes: Single/block transfer, burst transfer, and continuous transfer
• Transfers from the total address area to the total address area
• Transfer frequency of up to 65,536 pulses
• Transfer end interrupt function
• Transfer address increment/decrement selectable by software
• Three external transfer request input pins, three external transfer request acknowledgment
output pins, and three external transfer end output pins
■
DMAC Registers
Figure 15.1-1 shows the DMAC registers.
Figure 15.1-1 DMAC Registers
31 0
00000200H DPDP
00000204H DACSR
00000208H DATCR
31 0
DPDP + 0H DMA
ch-0
DPDP + 0CH DMA
ch-1
:
:
DPDP + 54H DMA
ch-7
[Inside DMAC: DMAC internal registers]
[On RAM: DMA descriptors]
descriptor
descriptor
descriptor