NXP Semiconductors MPC5644A, Reference Manual, Page: 169 / 1735

Enhanced Direct Memory Access Controller (eDMA)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor 169
167–175 /
0x14 [7:15]
CITER
[6:14]
Current major iteration count
This 9 or 15-bit count represents the current major loop count for the channel. It
is decremented each time the minor loop is completed and updated in the
transfer control descriptor memory. After the major iteration count is exhausted,
the channel performs a number of operations (for example, final source and
destination address calculations), optionally generating an interrupt to signal
channel completion before reloading the CITER field from the beginning
iteration count (BITER) field.
Note: When the CITER field is initially loaded by software, it must be set to the
same value as that contained in the BITER field.
Note: If the channel is configured to execute a single service request, the initial
values of BITER and CITER should be 0x0001.
176–191 /
0x14 [16:31]
DOFF
[0:15]
Destination address signed Offset
Sign-extended offset applied to the current destination address to form the
next-state value as each destination write is completed.
192–223 /
0x18 [0:31]
DLAST_SGA
[0:31]
Last destination address adjustment or the memory address for the next transfer
control descriptor to be loaded into this channel (scatter-gather).
If scatter-gather processing for the channel is disabled (EDMA_TCD[E_SG] = 0)
then
• Adjustment value added to the destination address at the completion of the
outer major iteration count.
This value can be applied to restore the destination address to the initial value,
or adjust the address to reference the next data structure.
Otherwise,
• This address points to the beginning of a 0-modulo-32 byte region containing
the next transfer control descriptor to be loaded into this channel. This
channel reload is performed as the major iteration count completes. The
scatter-gather address must be 0-modulo-32 byte, otherwise a configuration
error is reported.
224 /
0x1C [0]
BITER.E_LINK Enables channel-to-channel linking on minor loop complete
As the channel completes the inner minor loop, this flag enables the linking to
another channel, defined by BITER.LINKCH[0:5]. The link target channel
initiates a channel service request via an internal mechanism that sets the bit
EDMA_TCD[START] of the specified channel. If channel linking is disabled, the
BITER 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: When the TCD is first loaded by software, this field must be set equal to
the corresponding CITER field. Otherwise, a configuration error is
reported. As the major iteration count is exhausted, the contents of this
field is reloaded into the CITER field.
Table 8-20. TCDn field descriptions (continued)
Bits /
Word offset
[n:n]
Name Description