Description
Reset
Type
Name
Bit/Field
Transfer Size (minus 1)
This field configures the total number of items to transfer. The value of
this field is 1 less than the number to transfer (value 0 means transfer
1 item). The maximum value for this 10-bit field is 1023 which represents
a transfer size of 1024 items.
The transfer size is the number of items, not the number of bytes. If the
data size is 32 bits, then this value is the number of 32-bit words to
transfer.
The μDMA controller updates this field immediately prior to entering the
arbitration process, so it contains the number of outstanding items that
is necessary to complete the μDMA cycle.
-
RW
XFERSIZE
13:4
Next Useburst
This field controls whether the Useburst
SET[n]
bit is automatically set
for the last transfer of a peripheral scatter-gather operation. Normally,
for the last transfer, if the number of remaining items to transfer is less
than the arbitration size, the μDMA controller uses single transfers to
complete the transaction. If this bit is set, then the controller uses a burst
transfer to complete the last transfer.
-
RW
NXTUSEBURST
3
μDMA Transfer Mode
This field configures the operating mode of the μDMA cycle. Refer to
“Transfer Modes” on page 685 for a detailed explanation of transfer
modes.
Because this register is in system RAM, it has no reset value. Therefore,
this field should be initialized to 0 before the channel is enabled.
Description
Value
Stop
0x0
Basic
0x1
Auto-Request
0x2
Ping-Pong
0x3
Memory Scatter-Gather
0x4
Alternate Memory Scatter-Gather
0x5
Peripheral Scatter-Gather
0x6
Alternate Peripheral Scatter-Gather
0x7
-
RW
XFERMODE
2:0
XFERMODE Bit Field Values.
Stop
Channel is stopped or configuration data is invalid. No more transfers can occur.
Basic
For each trigger (whether from a peripheral or a software request), the μDMA controller performs
the number of transfers specified by the
ARBSIZE
field.
Auto-Request
The initial request (software- or peripheral-initiated) is sufficient to complete the entire transfer
of
XFERSIZE
items without any further requests.
June 18, 2014
708
Texas Instruments-Production Data
Micro Direct Memory Access (μDMA)