NXP Semiconductors K22F series, Reference Manual, Page: 495 / 1407

DMA request
DMA request
DMA request
Minor loop
Minor loop
Minor loop
Major loop
Current major
loop iteration
count (CITER)
3
2
1
Source or destination memory
Figure 22-5. Example of multiple loop iterations
The following figure lists the memory array terms and how the TCD settings interrelate.
xADDR: (Starting address)
xLAST: Number of bytes added to
current address after major loop
(typically used to loop back)
Minor loop
(NBYTES in
minor loop,
often the same
value as xSIZE)
Minor loop
Last minor loop
Offset (xOFF): number of bytes added to
current address after each transfer
(often the same value as xSIZE)
Each DMA source (S) and
destination (D) has its own:
Address (xADDR)
Size (xSIZE)
Offset (xOFF)
Modulo (xMOD)
Last Address Adjustment (xLAST)
where x = S or D
Peripheral queues typically
have size and offset equal
to NBYTES.
xSIZE: (size of one
data transfer)
Figure 22-6. Memory array terms
22.5.2 Programming errors
The eDMA performs various tests on the transfer control descriptor to verify consistency
in the descriptor data. Most programming errors are reported on a per channel basis with
the exception of channel priority error (ES[CPE]).
Chapter 22 Enhanced Direct Memory Access (eDMA)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 495