CHAPTER 12 DMA FUNCTIONS
User’s Manual U13850EJ6V0UD
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12.3
Configuration
Figure 12-1. Block Diagram of DMA
DMA transfer trigger
(INT signal)
DMA transfer
request control
Channel controller
DMA peripheral I/O address
register n (DIOAn)
DMA byte count
register n (DBCn)
DMA internal RAM address
register n (DRAn)
DMA channel control
register n (DCHCn)
DMA transfer acknowledge signal
CPU
Interface control
Internal
RAM
Internal bus
INTDMAn
Peripheral
I/O register
Remark
n = 0 to 5
(1) DMA transfer request control block
The DMA transfer request control block generates a DMA transfer request signal for the CPU when the required
DMA transfer trigger (INT signal) is input.
When the DMA transfer request signal is acknowledged, the CPU generates a DMA transfer acknowledge signal
for the channel control block and interface control block after the current CPU processing has finished.
For the INT signal, refer to the TTYPn1 and TTYPn0 bits in
12.4 (5) DMA channel control registers 0 to 5
(DCHC0 to DCHC5)
.
(2) Channel control block
The channel control block distinguishes the DMA transfer channel (DMA0 to DMA5) to be transferred and
controls the internal RAM, peripheral I/O addresses, and access cycles (internal RAM: 1 clock, peripheral I/O
register: 3 clocks) set by the peripheral I/O registers of the channel to be transferred, the transfer direction, and
the transfer count. In addition, it also controls the priority order when two or more DMAn transfer triggers (INT
signals) are generated simultaneously.
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