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Chapter 7
DMA Functions (DMA Controller)
Preliminary User’s Manual U15839EE1V0UM00
7.8 DMA
Channel
Priorities
The DMA channel priorities are fixed as follows.
DMA channel 0 > DMA channel 1 > DMA channel 2 > DMA channel 3
These priorities are valid in the TI state only. In the block transfer mode, the channel used for transfer is
never switched.
In the single-step transfer mode, if a higher priority DMA transfer request is issued while the bus is
released (in the TI state), the higher priority DMA transfer request is acknowledged.
7.9 DMA Transfer Start Factors
There are two types of DMA transfer start factors, as shown below.
(1)
Request from on-chip peripheral I/O
If the ENn and the TCn bits of the DCHCn register are set as shown below, and an interrupt
request is issued from the on-chip peripheral I/O that is set in the DTFRn register, the DMA trans-
fer starts.
• ENn bit = 1
• TCn bit = 0
(2)
Request from software
If the STGn, the ENn and the TCn bits of the DCHCn register are set as follows, the DMA transfer
starts.
• STGn bit = 1
• ENn bit = 1
• TCn bit = 0
Remark:
n = 0 to 3
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