CC2430 Datasheet, PDF (89/234 Pages) Texas Instruments – A True System-on-Chip solution for 2.4 GHz IEEE 802.15.4 / ZigBee-TM

CC2430
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Figure 18: Variable Length (VLEN) Transfer Options
13.2.2.5 Trigger Event
Each DMA channel can be set up to sense on
a single trigger. This field determines which
trigger the DMA channel shall sense.
13.2.2.6 Source and Destination Increment
When the DMA channel is armed or rearmed
the source and destination addresses are
transferred to internal address pointers. The
possibilities for address increment are :
• Increment by zero. The address
pointer shall remain fixed after each
transfer.
• Increment by one. The address
pointer shall increment one count
after each transfer.
• Increment by two. The address
pointer shall increment two counts
after each transfer.
• Decrement by one. The address
pointer shall decrement one count
after each transfer.
13.2.2.7 DMA Transfer Mode
The transfer mode determines how the DMA
channel behaves when it starts transferring
data. There are four transfer modes described
below:
Single. On a trigger a single DMA transfer
occurs and the DMA channel awaits the next
trigger. After the number of transfers specified
by the transfer count, are completed, the CPU
is notified and the DMA channel is disarmed.
Block. On a trigger the number of DMA
transfers specified by the transfer count is
performed as quickly as possible, after which
the CPU is notified and the DMA channel is
disarmed.
Repeated single. On a trigger a single DMA
transfer occurs and the DMA channel awaits
the next trigger. After the number of transfers
specified by the transfer count are completed,
the CPU is notified and the DMA channel is
rearmed.
Repeated block. On a trigger the number of
DMA transfers specified by the transfer count
is performed as quickly as possible, after
which the CPU is notified and the DMA
channel is rearmed.
13.2.2.8 DMA Priority
A DMA priority is associated with each DMA
access port and is configurable for each DMA
channel. The DMA priority is used to
CC2430 PRELIMINARY Data Sheet (rev. 1.03) SWRS036A
Page 89 of 232