Table 7.1. Arbitration Slot Order
Arb-
slot
order
8
4
8
2
8
4
8
1
8
4
8
2
8
4
Arb-
slot1
1
Arb-
slot2
1
1
Arb-
slot4
1
1
1
1
Arb-
slot8
1
1
1
1
1
1
1
The top row shows the order at which the arbitration slots are executed. The remaining part of the table shows a more visual interpreta-
tion of the arbitration order.
For example, if we have one low latency channel (CHNL0) and two latency tolerant channels (CHNL1 and CHNL2). We could use the
following settings.
LDMA_CTRL.NUMFIXED = 0; set round robbin for all channels.
CHNL0_CFG.ARBSLOTS = TWO;
CHNL1_CFG.ARBSLOTS = ONE;
CHNL2_CFG.ARBSLOTS = ONE;
If all channels are constantly requesting transfers, then the arbitration order is: CHNL0, CHNL1, CHNL0, CHNL2, CHNL0, CHNL1,
CHNL0, CHNL2, CHNL0, etc
Note, there are no channels assigned to arbitration slot four or eight in this exampl, so thoes slots are skipped and the final sequence is
ARBSLOT2, ARBSLOT1, ARBSLOT2, ARBSLOT1, etc...
Channel 1 and Channel 2 are selected in round robin order when arbitration slot 1 is executed.
If we replace the ARBSLOTS value for channel 0 with EIGHT, then the sequence would look like the following:
CHNL0, CHNL0, CHNL0, CHNL0, CHNL1, CHNL0, CHNL0, CHNL0, CHNL2, CHNL0, CHNL0, CHNL0, CHNL0, CHNL1, etc.
EFM32JG1 Reference Manual
LDMA - Linked DMA Controller
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