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S3C2440A RISC MICROPROCESSOR DMA
8-13
DMA MASK TRIGGER (DMASKTRIG) REGISTER
Register Address R/W Description Reset Value
DMASKTRIG0 0x4B000020 R/W DMA 0 mask trigger register 000
DMASKTRIG1 0x4B000060 R/W DMA 1 mask trigger register 000
DMASKTRIG2 0x4B0000A0 R/W DMA 2 mask trigger register 000
DMASKTRIG3 0x4B0000E0 R/W DMA 3 mask trigger register 000
DMASKTRIGn Bit Description Initial State
STOP [2] Stop the DMA operation.
1: DMA stops as soon as the current atomic transfer ends. If
there is no current running atomic transfer, DMA stops
immediately. The CURR_TC, CURR_SRC, and CURR_DST
will be 0.
Note: Due to possible current atomic transfer, “stop” operation
may take several cycles. The finish of the operation (i.e. actual
stop time) can be detected as soon as the channel on/off bit
(DMASKTRIGn[1]) is set to off. This stop is “actual stop”.
0
ON_OFF [1] DMA channel on/off bit.
0: DMA channel is turned off. (DMA request to this channel is
ignored.)
1: DMA channel is turned on and the DMA request is handled.
This bit is automatically set to off if we set the DCONn[22] bit to
“no auto reload” and/or STOP bit of DMASKTRIGn to “stop”.
Note that when DCON[22] bit is "no auto reload", this bit
becomes 0 when CURR_TC reaches 0. If the STOP bit is 1,
this bit becomes 0 as soon as the current atomic transfer is
completed.
Note. This bit should not be changed manually during DMA
operations (i.e. this has to be changed only by using DCON[22] or
STOP bit).
0
SW_TRIG [0] Trigger the DMA channel in S/W request mode.
1: it requests a DMA operation to this controller.
Note that this trigger gets effective after S/W request mode has
to be selected (DCONn[23]) and channel ON_OFF bit has to be
set to 1 (channel on). When DMA operation starts, this bit is
cleared automatically.
0
Note
You are allowed to change the values of DISRC register, DIDST registers, and TC field of DCON register. Those
changes take effect only after the finish of current transfer (i.e. when CURR_TC becomes 0). On the other hand,
any change made to other registers and/or fields takes immediate effect. Therefore, be careful in changing those
registers and fields.