Des Mode; Gdma Function Description; Gdma Transfers; Starting/Ending Gdma Transfers - Samsung S3C2501X User Manual

S3C2501X

9.4.4 DES MODE

S3C2501X has only one DES. Any channel of GDMA can transmit the data of DES. If GDMA mode selection bit
"100" or "101", GDMA gets ready to communicate with DES. If GDMA mode is "100" (DES IN mode) and GDMA
receives the request signal transmitted from DES, GDMA transfers IN data of DES in memory into IN buffer/FIFO
of DES. If GDMA mode is "101" (DES OUT mode) and GDMA receives the request signal transmitted from DES,
GDMA transfers OUT data of OUT buffer/FIFO of DES into memory.
When GDMA is DES mode, GDMA transmits two words by single request. When GDMA is DES mode
and four-burst mode is enabled, GDMA transmits four words by single request. But DTCR register only
has to be a multiple of 8 (2 words), because GDMA can transmit the last misaligned data. (At this time if
GDMA count register is zero, the operation is ended.) In DES mode, you should set word ("10") on
transfer size (TS) [7:6] of DCON register. In DES IN mode, you don't need to care the destination
address direction (DD) [11:10] of DCON register either the DDAR register. In DES OUT mode, you don't
need to care the source address direction (SD) [9:8] of DCON register either the DSAR register.

9.5 GDMA FUNCTION DESCRIPTION

The following sections provide a functional description of the GDMA controller operations.

9.5.1 GDMA TRANSFERS

The GDMA transfers data directly between a requester and a target. The requester and target can be memory,
HUART, DES, special function registers, or external devices. An external device requests the GDMA service by
activating xGDMA_Req signal. A channel is programmed by writing to registers, which contain the requester
address, the target address, the amount of data, and other control contents. HUART, DES, external I/O, or
software (memory) can request GDMA service. HUART and DES are internally connected to the GDMA.

9.5.2 STARTING/ENDING GDMA TRANSFERS

GDMA starts to transfer data after the GDMA receives service request from xGDMA_Req signal, HUART, DES,
or software. When the entire buffer of data has been transferred, the GDMA becomes idle. If you want to perform
another buffer transfer, the GDMA must be reprogrammed. Although the same buffer transfer will be performed
again, the GDMA must be reprogrammed.
NOTE
GDMA CONTROLLER
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