EFM32WG Datasheet, PDF (61/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

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Bit
[13:4]
Field
n_minus_1
Value
N¹
Description
Configures the controller to perform N DMA transfers, where N is a multiple of four
[3]
next_useburst -
When set to 1, the controller sets the chnl_useburst_set [C] bit to 1 after the
alternate transfer completes
1_{Because the R_power field is set to four, you must set N to be a multiple of four. The value given by N/4 is the number of times}
that you must configure the alternate data structure.
See Section 8.4.3.3 (p. 65) for more information.
Figure 8.5 (p. 61) shows a peripheral scatter-gather example.
Figure 8.5. Peripheral scatter-gather example
Init ializat ion:1. Configure prim ary t o enable t he copy A, B, C, and D operat ions: cycle_ct rl = b110, 2^R = 4, N = 16.
2. Write the prim ary source data in m em ory, using the structure shown in the following table.
Dat a for Task A
Dat a for Task B
Dat a for Task C
Dat a for Task D
src_dat a_end_pt r
0 x 0 A0 0 0 0 0 0
0 x 0 B0 0 0 0 0 0
0 x 0 C0 0 0 0 0 0
0x0D000000
dst _dat a_end_pt r
0 x 0 AE0 0 0 0 0
0 x 0 BE0 0 0 0 0
0 x 0 CE0 0 0 0 0
0 x 0 D E0 0 0 0 0
c h a n n e l _c f g
cycle_ct rl = b111, 2^R = 4, N = 3
cycle_ct rl = b111, 2^R = 2, N = 8
cycle_ct rl = b111, 2^R = 8, N = 5
cycle_ct rl = b001, 2^R = 4, N = 4
Unused
0 x XXXXXXXX
0 x XXXXXXXX
0 x XXXXXXXX
0 x XXXXXXXX
Peripheral scat t er-gat her t ransact ion:
Prim a ry
Re q u e st
Copy from A in
m em ory, to Alternate
Copy from B in
m em ory, to Alternate
Re q u e st
Alt e r n a t e
Task A
For all prim ary t o alt ernat e t ransit ions,
the controller does not enter the
arbitration process and im m ediately
perform s the DMA transfer that the
alternate channel control data structure
specifies.
N = 3, 2^R = 4
Re q u e st
Re q u e st
Re q u e st
Copy from C in
m em ory, to Alternate
Re q u e st
Task B
N = 8, 2^R = 2
Copy from D in
m em ory, to Alternate
Re q u e st
Task C
N = 5, 2^R = 8
Task D
N = 4, 2^R = 4
d m a _d on e [ C]
In Figure 8.5 (p. 61) :
Initialization
1. The host processor configures the primary data structure to operate in peripheral
scatter-gather mode by setting cycle_ctrl to b110. Because a data structure for a
single channel consists of four words then you must set 2^R to 4. In this example,
there are four tasks and therefore N is set to 16.
2. The host processor writes the data structure for tasks A, B, C, and D to the
memory locations that the primary src_data_end_ptr specifies.
3. The host processor enables the channel.
The peripheral scatter-gather transaction commences when the controller receives a request on
dma_req[ ]. The transaction continues as follows:
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
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