CHAPTER 6 DMA FUNCTIONS (DMA CONTROLLER)
User’s Manual U12688EJ4V0UM00
193
6.12.3 Forcible termination
In addition to forcible interruption of DMA transfer by NMI input, DMA transfer can also be terminated forcibly by
the INITn bit of the DCHCn register. Examples of the forcible termination operation are shown below (n = 0 to 3).
Figure 6-11. Example of Forcible Termination of DMA Transfer
(a) During block transfer through DMA channel 2, transfer through DMA channel 3 is started.
DSA2, DDA2, DBC2,
DADC2, DCHC2
DCHC2
(INIT2 bit = 1)
Register set
Register set
EN2 bit = 1
TC2 bit = 0
EN2 bit
→
0
TC2 bit = 0
DMARQ2
DSA3, DDA3, DBC3,
DADC3, DCHC3
Register set
EN3 bit = 1
TC3 bit = 0
EN3 bit
→
0
TC3 bit
→
1
DMA channel 3 transfer termination
DMA channel 3 transfer start
DMA channel 2 transfer is forcibly terminated.
The bus is released.
DMARQ3
CPU CPU CPU CPU DMA2 DMA2 DMA2 DMA2 DMA2 CPU DMA3 DMA3 DMA3 DMA3 CPU CPU CPU
(b) During block transfer through DMA channel 1, transfer is terminated, and a different
conditional transfer is executed.
DSA1, DDA1, DBC1,
DADC1, DCHC1
DCHC1
(INIT1 bit = 1)
Register set
DSA1, DDA1,
DBC1
Register set
Register set
DADC1,
DCHC1
Register set
EN1 bit = 1
TC1 bit = 0
EN1 bit
→
0
TC1 bit = 0
EN1 bit
→
0
TC1 bit
→
1
EN1 bit = 1
TC1 bit = 0
DMARQ1
DMA channel 1 transfer termination
DMA channel 1 transfer is forcibly terminated.
The bus is released.
CPU CPU CPU CPU DMA1 DMA1 DMA1 DMA1 DMA1 DMA1 CPU CPU CPU CPU DMA1 DMA1 DMA1 CPU
Remark
During DMA transfer, the next condition can be set, because the DSAn, DDAn, DBCn registers are
buffered registers, but the setting to the DADCn register is ignored (refer to 6.9 Next Address
Setting Function).
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