NXP Semiconductors PXN2020, Reference Manual, Page: 546 / 1376

Enhanced Direct Memory Access Controller (eDMA)
PXN20 Microcontroller Reference Manual, Rev. 1
24-26 Freescale Semiconductor
66–85
0x8 [2-21]
MLOFF or
NBYTES
1
[0:19]
Inner “minor” byte transfer count or Minor loop offset
If both SMLOE and DMLOE are cleared, this field is part of the byte transfer count.
If either SMLOE or DMLOE are set, this field represents a sign-extended offset applied
to the source or destination address to form the next-state value after the minor loop is
completed.
86–95 /
0x8 [22:31]
NBYTES
1
Inner “minor” byte transfer count. Number of bytes to be transferred in each service
request of the channel. As a channel is activated, the contents of the appropriate TCD is
loaded into the eDMA engine, and the appropriate reads and writes performed until the
complete byte transfer count has been transferred. This is an indivisible operation and
cannot be stalled or halted. Once the minor count is exhausted, the current values of the
SADDR and DADDR are written back into the local memory, the major iteration count is
decremented and restored to the local memory. If the major iteration count is completed,
additional processing is performed.
Note: The NBYTES value of 0x0000_0000 is interpreted as 0x1_0000_0000, thus
specifying a 4 GB transfer.
96–127 /
0xC [0:31]
SLAST
[0:31]
Last source address adjustment. Adjustment value added to the source address at the
completion of the outer major iteration count. This value can be applied to “restore” the
source address to the initial value, or adjust the address to reference the next data
structure.
128–159 /
0x10 [0:31]
DADDR
[0:31]
Destination address. Memory address pointing to the destination data.
160 /
0x14 [0]
CITER.E_LINK Enable channel-to-channel linking on minor loop completion. As the channel completes
the inner minor loop, this flag enables the linking to another channel, defined by
CITER.LINKCH[0:5]. The link target channel initiates a channel service request via an
internal mechanism that sets the TCD.START bit of the specified channel. If channel
linking is disabled, the CITER value is extended to 15 bits in place of a link channel
number. If the major loop is exhausted, this link mechanism is suppressed in favor of the
MAJOR.E_LINK channel linking.
0 The channel-to-channel linking is disabled.
1 The channel-to-channel linking is enabled.
Note: This bit must be equal to the BITER.E_LINK bit. Otherwise, a configuration error
is reported.
161–166 /
0x14 [1:6] CITER
[0:5]
or
CITER.LINKCH
[0:5]
Current major iteration count or link channel number.
If channel-to-channel linking is disabled (TCD.CITER.E_LINK = 0), then
• No channel-to-channel linking (or chaining) is performed after the inner minor loop is
exhausted. TCD bits [161:175] are used to form a 15-bit CITER field.
Otherwise,
• After the minor loop is exhausted, the DMA engine initiates a channel service request
at the channel defined by CITER.LINKCH[0:5] by setting that channel’s TCD.START
bit.
Table 24-20. TCDn Field Descriptions (continued)
Bits /
Word Offset
[n:n]
Name Description