2. Minor loop done → set TCD12_CSR[START] bit
3. Minor loop done → set TCD12_CSR[START] bit
4. Minor loop done, major loop done→ set TCD7_CSR[START] bit
When minor loop linking is enabled (TCDn_CITER[E_LINK] = 1), the
TCDn_CITER[CITER] field uses a nine bit vector to form the current iteration count.
When minor loop linking is disabled (TCDn_CITER[E_LINK] = 0), the
TCDn_CITER[CITER] field uses a 15-bit vector to form the current iteration count. The
bits associated with the TCDn_CITER[LINKCH] field are concatenated onto the CITER
value to increase the range of the CITER.
Note
The TCDn_CITER[E_LINK] bit and the
TCDn_BITER[E_LINK] bit must equal or a configuration error
is reported. The CITER and BITER vector widths must be
equal to calculate the major loop, half-way done interrupt point.
The following table summarizes how a DMA channel can link to another DMA channel,
i.e, use another channel's TCD, at the end of a loop.
Table 22-10. Channel Linking Parameters
Desired Link
Behavior
TCD Control Field Name Description
Link at end of
Minor Loop
CITER[E_LINK]
Enable channel-to-channel linking on minor loop completion (current
iteration)
CITER[LINKCH] Link channel number when linking at end of minor loop (current iteration)
Link at end of
Major Loop
CSR[MAJOR_E_LINK] Enable channel-to-channel linking on major loop completion
CSR[MAJOR_LINKCH] Link channel number when linking at end of major loop
22.5.7 Dynamic programming
This section provides recommended methods to change the programming model during
channel execution.
22.5.7.1
Dynamically changing the channel priority
The following two options are recommended for dynamically changing channel priority
levels:
Chapter 22 Enhanced Direct Memory Access (eDMA)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 503
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