Freescale Semiconductor MCF54455 Reference Manual page 435

Enhanced Direct Memory Access (eDMA)
Field
31–0 Destination address. Memory address pointing to the destination data.
DADDR
Address: 0xFC04_5014 + (0x20 n) (TCDn_CITER)
15
R
E_LINK = 1 E_LINK
W
R
E_LINK = 0 E_LINK
W
Reset —
Figure 19-24. TCDn Current Major Iteration Count (TCDn_CITER)
Field
15 Enable channel-to-channel linking on minor-loop complete. As the channel completes the minor loop, this
E_LINK flag enables linking to another channel, defined by the LINKCH field. The link target channel initiates a
channel service request via an internal mechanism that sets the TCDn_CSR[START] bit of the specified
channel.
If channel linking is disabled, the CITER 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: This bit must be equal to the BITER.E_LINK bit. Otherwise, a configuration error is reported.
14–13 Reserved, must be cleared.
12–9 Link channel number. If channel-to-channel linking is enabled (E_LINK = 1), then after the minor loop is
LINKCH exhausted, the eDMA engine initiates a channel service request to the channel defined by these four bits
by setting that channel's TCDn_CSR[START] bit.
0–15 Link to DMA channel 0–15
14–0 or Current major iteration count. This 9-bit (E_LINK = 1) or 15-bit (E_LINK = 0) count represents the current
8–0 major loop count for the channel. It is decremented each time the minor loop is completed and updated in
CITER the transfer control descriptor memory. After 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.
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.
19-20
Table 19-25. TCDn_DADDR Field Descriptions
14 13 12 11 10
0 0
LINKCH
— — — — —
Table 19-26. TCDn_CITER Field Descriptions
Description
9 8 7 6 5
CITER
— — — — —
Description
Access: User read/write
4 3 2 1 0
CITER
— — — — —
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