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Chapter 15
DMA Functions (DMA Controller)
User’s Manual U16702EE3V2UD00
(7)
DMA channel control register (DMCHCn)
The DMCHCn register controls the DMA transfer operation mode. It can be read or written in 8-bit
or 1-bit units.
The RQST, ACF, FCLR, STG and EN bits are initialized by POWER=0. Initial value is 00H by reset.
Figure 15-10:
DMA Channel Control Register (DMCHCn) Format (1/4)
Cautions: 1. Write to TCS bit is permitted only when POWER bit = 0.
2. Before changing the TCS bit, mask the corresponding INTDMAn interrupt. After
changing the TCS bit, clear any pending INTDMAn interrupt request flag.
The DMA controller has the option to mirror the selected input trigger (IFCn[5:0] bits of the DTFRn
register) to the INTDMA signal. This mirroring is independent from the status of the DMA channel
(disabled, enabled, DMA in progress or ended). The mirror function is used in devices where DMA
interrupts are to be shared with interrupts also serving as interrupt request signals to the DMA
controller.
For V850E/RS1, there is no sharing of interrupts needed, as each of the DMA channels has its
own interrupt assigned on interrupt controller side. Therefore it is highly recommended NOT to use
the TCS=0 setting.
Please refer to section
15.4.4 on page 521
for further explanation of the TCS bit and the result-
ing timing of the DMA interrupt.
DMCHC0=FFFFFDE0H, DMCHC1=FFFFFDE1H, DMCHC2=FFFFFDE2H,
DMCHC3=FFFFFDE3H, DMCHC4=FFFFFDE4H, DMCHC5=FFFFFDE5H
Symbol
7
6
5
4
3
2
1
0
Address
After reset
DMCHCn
0
0
TCS
RQST
ACF
FCLR
STG
EN
00H
R/W
R
R
R/W
R
R
R/W
R/W
R/W
TCS
DMA Interrupt Timing Generation
0
INTDMAn is a direct mirror of the selected DMA request input signal of channel n
1
INTDMAn timing is based on DMA execution.
RQST
Transfer Request Status Flag
0
No DMA transfer request pending. This bit is cleared either by start of the DMA transfer or by
writing 0 to the FCLR bit.
1
DMA transfer request pending.
This bit is set by a DMA request signal input or when writing 1 to the STG bit.
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Содержание V850E/RS1
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