LM3S9B81 Datasheet, PDF (238/1155 Pages) Texas Instruments – Stellaris® LM3S9B81 Microcontroller

Micro Direct Memory Access (μDMA)
8.2.1
Each channel also has a configurable arbitration size. The arbitration size is the number of items
that are transferred in a burst before the μDMA controller rearbitrates for channel priority. Using the
arbitration size, it is possible to control exactly how many items are transferred to or from a peripheral
each time it makes a μDMA service request.
Channel Assignments
μDMA channels 0-31 are assigned to peripherals according to the following table. The DMA Channel
Assignment (DMACHASGN) register (see page 284) can be used to specify the primary or secondary
assignment. If the primary function is not available on this microcontroller, the secondary function
becomes the primary function. If the secondary function is not available, the primary function is the
only option.
Note: Channels noted in the table as "Available for software" may be assigned to peripherals in
the future. However, they are currently available for software use. Channel 30 is dedicated
for software use.
The USB endpoints mapped to μDMA channels 0-3 can be changed with the USBDMASEL
register (see page 1000).
If a channel is marked with "*" below and is configured to transfer data with a software
request using the DMASWREQ register, this channel must also be enabled in the
DMAENASET register.
Table 8-1. μDMA Channel Assignments
μDMA Channel
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Primary Assignment
USB Endpoint 1 Receive
USB Endpoint 1 Transmit
USB Endpoint 2 Receive
USB Endpoint 2 Transmit
USB Endpoint 3 Receive
USB Endpoint 3 Transmit
Ethernet Receive
Ethernet Transmit
UART0 Receive
UART0 Transmit
SSI0 Receive
SSI0 Transmit
Available for software
Available for software
ADC0 Sample Sequencer 0
ADC0 Sample Sequencer 1
ADC0 Sample Sequencer 2
ADC0 Sample Sequencer 3
General-Purpose Timer 0A
General-Purpose Timer 0B
General-Purpose Timer 1A
General-Purpose Timer 1B
UART1 Receive
Secondary Assignment
UART2 Receive*
UART2 Transmit*
General-Purpose Timer 3A*
General-Purpose Timer 3B*
General-Purpose Timer 2A*
General-Purpose Timer 2B*
General-Purpose Timer 2A*
General-Purpose Timer 2B*
UART1 Receive
UART1 Transmit
SSI1 Receive
SSI1 Transmit
UART2 Receive*
UART2 Transmit*
General-Purpose Timer 2A*
General-Purpose Timer 2B*
Available for software
Available for software
General-Purpose Timer 1A
General-Purpose Timer 1B
EPI0 NBRFIFO*
EPI0 WFIFO*
Available for software
238
June 29, 2010
Texas Instruments-Advance Information