LM3S3759 Luminary Micro, Inc, LM3S3759 Datasheet - Page 207

• Manufacturer Part Number: LM3S3759
• Description: Lm3s3759 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

9.6
June 02, 2008
Bit/Field
2:0
μDMA Register Descriptions
The register addresses given are relative to the μDMA base address of 0x400F.F000.
XFERMODE
Name
Type
R/W
Reset
-
Preliminary
Description
DMA Transfer Mode
Since this register is in system RAM, it has no reset value. Therefore,
this field should be initialized to 0 before the channel is enabled.
The operating mode of the DMA cycle. Refer to “Transfer
Modes” on page 185 for a detailed explanation of transfer modes.
Value
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
Description
Stop
Channel is stopped, or configuration data is invalid.
Basic
The controller must receive a new request, prior to it entering
the arbitration process, to enable the DMA cycle to complete.
Auto-Request
The initial request (software- or peripheral-initiated) is sufficient
to complete the entire transfer of XFERSIZE items without any
further requests.
Ping-Pong
The controller performs a DMA cycle using one of the channel
control structures. After the DMA cycle completes, it performs
a DMA cycle using the other channel control structure. After the
next DMA cycle completes (and provided that the host processor
has updated the original channel control data structure), it
performs a DMA cycle using the original channel control data
structure. The controller continues to perform DMA cycles until
it either reads an invalid data structure or the host processor
changes this field to 0x1 or 0x2. See “Ping-Pong” on page 185.
Memory Scatter-Gather
When the controller operates in Memory Scatter-Gather mode,
you must only use this value in the primary channel control data
structure. See “Memory Scatter-Gather” on page 187.
Alternate Memory Scatter-Gather
When the controller operates in Memory Scatter-Gather mode,
you must only use this value in the alternate channel control
data structure.
Peripheral Scatter-Gather
When the controller operates in Peripheral Scatter-Gather mode,
you must only use this value in the primary channel control data
structure. See “Peripheral Scatter-Gather” on page 190.
Alternate Peripheral Scatter-Gather
When the controller operates in Peripheral Scatter-Gather mode,
you must only use this value in the alternate channel control
data structure.
LM3S3759 Microcontroller
207