BS_DMA controller
RM0082
348/844
Doc ID 018672 Rev 1
[23:21]
Dwidth
3’h0
Destination transfer width.
This 3 bits field states the width of destination (resp. source)
transfer, according to encoding:
3‘b000 = Byte (8 bit)
3‘b001 = Halfword (16 bit)
3‘b010 = Word (32 bit)
3‘b011 to 3‘b111 = Reserved
The hardware automatically packs and unpacks the data when
required.
Note: Transfers wider than the AHB master bus width are illegal.
Besides, the source and the destinations widths can be different
from each other.
[20:18]
Swidth
3’h0
Source transfer width.
This 3 bits field states the width of destination (resp. source)
transfer, according to encoding:
3‘b000 = Byte (8 bit)
3‘b001 = Halfword (16 bit)
3‘b010 = Word (32 bit)
3‘b011 to 3‘b111 = Reserved
The hardware automatically packs and unpacks the data when
required.
Note: Transfers wider than the AHB master bus width are illegal.
Besides, the source and the destinations widths can be different
from each other.
[17:15]
DBSize
3’h0
Destination burst size.
This 3 bits field indicates the number of transfers that make up a
destination (resp. source) burst transfer request, according to
the encoding:
3‘b000 = 1
3‘b001 = 4
3‘b010 = 8
3‘b011 = 16
3‘b100 = 32
3‘b101 = 64
3‘b110 = 128
3‘b111 = 256
This value must be set to the burst size of the destination (resp.
source) peripheral, being the burst size the amount of data that
is transferred when the n-th
DMACBREQ
signal goes active in the
destination (resp. source) peripheral. In case destination (resp.
source) is the memory, this value must be set to the memory
boundary size.
Note: Burst equal or greater than 32 are available only using
data-width 32. The data-width 8 and 16 support only bursts of
1,4,8 & 16.
Table 299.
DMACCnControl register bit assignments (continued)
Bit
Name
Reset value Description