Bit
Name
Description
This bit-field serves as the SYNCTRIG match value. A sync match triggers the load of the next linked DMA structure as
specified by link_mode, when: (SYNCTRIG & MATCHEN) == (MATCHVAL & MATCHEN).
8.3.7.3 WRI Descriptor Structure
This descriptor defines a write-immediate structure. This allows a list of descriptors to write a value to a register or memory location. For
example, if a channel wishes to perform two loops in a descriptor sequence a WRI may be used to program the loop count for the
second loop.
This structure type can only be linked in from memory.
For specifying WRI structure type, set STRUCTTYPE to 2.
Name
Bit Position
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
CTRL
DONEIFSEN
STRUCTTYPE
SRC
DST
DSTADDR
LINK
LINKADDR
LINK
LINKMODE
Bit
Name
Description
1:0
STRUCTTYPE
Descriptor Type
This field indicates which type of descriptor this is. It must be 2 for a WRI descriptor.
20
DONEIFSEN
Done if Set indicator
If set the interrupt flag will be set when descriptor completes.
31:0
IMMVAL
Immediate Value for Write
This bit-field specifies the immediate data value that is to be written to the address pointed to by DSTADDR. Only one
write occurs for WRI structures.
31:0
DSTADDR
Address to write
This bit-field specifies the address the immediate data should be written to.
8.3.8 Interaction With the EMU
The LDMA interacts with the Energy Management Unit (EMU) to allow transfers from a low energy peripheral while in EM2 Deep Sleep.
For example, when using the LEUART in EM2 Deep Sleep the EMU can wake up the LDMA sufficiently long to allow data transfers to
occur. See section "DMA Support" in the LEUART documentation.
Similarly, when using the ADC in EM2 Deep Sleep or EM3 Stop the EMU can wake up the LDMA as needed to allow data transfers to
occur.
Reference Manual
LDMA - Linked DMA Controller
silabs.com
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