Information

21.3.1 Control Register (DMA_CR)
The CR defines the basic operating configuration of the DMA.
Arbitration can be configured to use either a fixed-priority or a round-robin scheme. For
fixed-priority arbitration, the highest priority channel requesting service is selected to
execute. The channel priority registers assign the priorities; see the DCHPRIn registers.
For round-robin arbitration, the channel priorities are ignored and channels are cycled
through (from high to low channel number) without regard to priority.
NOTE
For proper operation, writes to the CR register must be
performed only when the DMA channels are inactive; that is,
when TCDn_CSR[ACTIVE] bits are cleared.
Address: 4000_8000h base + 0h offset = 4000_8000h
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
R
0
CX ECX
W
Reset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bit
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
R
0
EMLM
CLM
HALT
HOE
0
ERCA
EDBG
0
W
Reset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
DMA_CR field descriptions
Field Description
31–18
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
17
CX
Cancel Transfer
0 Normal operation
1 Cancel the remaining data transfer. Stop the executing channel and force the minor loop to finish. The
cancel takes effect after the last write of the current read/write sequence. The CX bit clears itself after
the cancel has been honored. This cancel retires the channel normally as if the minor loop was
completed.
16
ECX
Error Cancel Transfer
0 Normal operation
1 Cancel the remaining data transfer in the same fashion as the CX bit. Stop the executing channel and
force the minor loop to finish. The cancel takes effect after the last write of the current read/write
Table continues on the next page...
Chapter 21 Direct Memory Access Controller (eDMA)
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
Freescale Semiconductor, Inc.
Preliminary
409
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