NXP Semiconductors MPC5602S, Справочное руководство

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Enhanced Direct Memory Access (eDMA)
MPC5606S Microcontroller Reference Manual, Rev. 7
Freescale Semiconductor 501
Figure 15-32 and Table 15-27 define word 6 of the TCD n structure, the dlast_sga field.
citer[0:5]
or
citer.linkch[0:5]
Current “major” iteration count

or

Link channel number
if (TCD.citer.e_link = 0) then
No channel-to-channel linking (or chaining) is performed after the inner “minor” loop is
exhausted. TCD word 5, bits [30:25] are used to form a 15 bit citer field.
else
After the “minor” loop is exhausted, the DMA engine initiates a channel service request at the
channel defined by citer.linkch[5:0] by setting that channel’s TCD.start bit.
The value contained in citer.linkch[5:0] must not exceed the number of implemented
channels.
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. Once the major iteration count is exhausted, the channel performs a
number of operations (e.g., 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.
When the citer field is initially loaded by software, it must be set to the same value as that
contained in the biter field.
If the channel is configured to execute a single service request, the initial values of biter and
citer should be 0x0001.
doff[16:31] 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.
Address: DMA_ (32 × n) + 0x18 Access: User read/write
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
R
dlast_sga[0:15]
W
Reset — — — — — — — — — — — — — — — —
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
R
dlast_sga[16:31]
W
Reset — — — — — — — — — — — — — — — —
Figure 15-32. TCDn Word 6 (TCDn.dlast_sga) field
Table 15-26. TCDn Word 5 (TCDn.{doff,citer}) field descriptions (continued)
Name Description