PXN20RM Datasheet, PDF (547/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

Bits /
Word Offset
[n:n]
167–175 /
0x14 [7:15]
176–191 /
0x14 [16:31]
192–223 /
0x18 [0:31]
224 /
0x1C [0]
Enhanced Direct Memory Access Controller (eDMA)
Table 24-20. TCDn Field Descriptions (continued)
Name
Description
CITER
[6:14]
DOFF
[0:15]
DLAST_SGA
[0:31]
BITER.E_LINK
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.
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.
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 (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.
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 TCD.START bit 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.
Freescale Semiconductor
PXN20 Microcontroller Reference Manual, Rev. 1
24-27