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AN666

USAGE GUIDE FOR SIM3U1XX, SIM3C1XX, AND SIM3L1XX DMA AND DTM MODULES

Silicon Laboratories 

AN666

Bit

17:14

Name

RPOWER

Function

Transfer Size Select.

This field determines the number of data transfers between each DMA channel re-arbi-

tration. The number of data transfers is given by:

Number of Transfers = 2RPOWER

This field is ignored for peripherals that support single data requests only. A value of 0

for RPOWER should be used for channels interfacing with these types of peripherals.

13:4

NCOUNT Transfer Total.

This field is the total number of transfers for the DMA channel. The total number is

NCOUNT + 1, so software requiring a total of 4 transfers would set the NCOUNT field

to 3.

The DMA controller decrements this field as transfers are made.

3

Reserved Must write 0 to this bit.

2:0

TMD

Transfer Mode.

000: Stop the DMA channel.

001: Use the Basic transfer type (single descriptor only).

010: Use the Auto-Request transfer type (single descriptor only).

011: Use the Ping-Pong transfer type (primary and alternate descriptors).

100: Use the Memory Scatter-Gather Primary transfer type (primary, alternate, and

scattered descriptors).

101: Use the Memory Scatter-Gather Alternate transfer type (primary, alternate, and

scattered descriptors).

110: Use the Peripheral Scatter-Gather Primary transfer type (primary, alternate, and

scattered descriptors).

111: Use the Peripheral Scatter-Gather Alternate transfer type (primary, alternate, and

scattered descriptors).

Rev. 0.1

7

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