CHAPTER 6 DMA FUNCTIONS (DMA CONTROLLER)
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User’s Manual U14492EJ3V0UD
6.10 DMA Transfer Start Factors
There are two types of DMA transfer start factors, as shown below.
(1) Request from software
If the STGn, Enn, and TCn bits of the DCHCn register are set as follows, DMA transfer starts (n = 0 to 3).
•
STGn bit = 1
•
Enn bit = 1
•
TCn bit = 0
(2) Request from on-chip peripheral I/O
If, when the Enn and TCn bits of the DCHCn register are set as shown below, an interrupt request is issued
from the on-chip peripheral I/O that is set in the DTFRn register, DMA transfer starts (n = 0 to 3).
•
Enn bit = 1
•
TCn bit = 0
6.11 Forcible Interruption
DMA transfer can be forcibly interrupted by NMI input during DMA transfer.
At such a time, the DMAC clears the Enn bit of the DCHCn register of all channels to 0 and the DMA transfer
disabled state is entered. An NMI request can then be acknowledged after the DMA transfer executed during NMI
input is terminated (n = 0 to 3).
If DMA transfer has been forcibly interrupted, perform forcible termination of the DMA using the INITn bit of the
DCHCn register and then initialize.
Содержание V850E/IA1 mPD703116
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