RM0082
BS_DMA controller
Doc ID 018672 Rev 1
349/844
19.7.21
DMAC Configuration register
The DMAC Configuration is a RW register which allow to configure the relevant DMA
channel. The DMAC Configuration bit assignments are given in
.
[14:12]
SBSize
3’h0
Source 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.
[11:00]
Transfer
Size
12’h0
Transfer size.
A write to this field sets the size of the transfer in case the
DMAC is the flow controller. This value counts down from the
original value to zero, and a read from this field provides then
the number of transfers still to be completed on the destination
bus.
Note: This field should be set to zero if the DMAC is not the flow
controller, avoiding then the DMAC might attempt to use a non-
zero value instead of ignoring the field.
Table 299.
DMACCnControl register bit assignments (continued)
Bit
Name
Reset value Description
Table 300.
DMAC Configuration register bit assignments
Bit
Name
Reset value Description
[31:19]
Reserved
-
Read: undefined. Write as zero.
[18]
H
1’h0
Halt.
Setting this bit, extra source DMA requests are ignored
(otherwise enabled), and the content of channel FIFO is
drained. This bit can be jointly used with the active bit (A field
in this register) and the channel enable bit (E field in this
register) to cleanly disable a DMA channel.
[17]
A
1’h0
Active (read-only).
If this read-only field is set, it means that there is still data in
the channel FIFO. This bit can be jointly used with the halt bit
(H field in this register) and the channel enable bit (E field in
this register) to cleanly disable a DMA channel.