NXP Semiconductors MPC5566, Reference Manual

Page: 390 / 1268

Enhanced Direct Memory Access (eDMA)
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 9-29
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 (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 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.
225–230
0x1C
[1:6]
BITER
[0:5]
or
BITER.LINKCH
[0:5]
Beginning or starting “major” iteration count or link channel number.
If channel-to-channel linking is disabled (TCD.BITER.E_LINK = 0), then
• No channel-to-channel linking (or chaining) is performed after the inner minor loop is
exhausted. TCD bits [225:239] are used to form a 15-bit BITER field.
Otherwise
• After the minor loop is exhausted, the eDMA engine initiates a channel service request
at the channel, defined by BITER.LINKCH[0:5], by setting that channel’s TCD.START
bit.
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.
231–239
0x1C
[7:15]
BITER
[6:14]
Beginning or starting major iteration count. As the transfer control descriptor is first loaded
by software, this field must be equal to the value in the CITER field. As the major iteration
count is exhausted, the contents of this field is reloaded into the CITER field.
Note: If the channel is configured to execute a single service request, the initial values
of BITER and CITER must be 0x0001.
Table 9-19. TCD n Field Descriptions (continued)
Bits
Word Offset
[n:n]
Field Name Description