PRELIMINARY
DMA
S3C6400 RISC MICROPROCESSOR
11-6
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
DMA INTERFACE
DMA request signals
The DMA request signals are used by peripherals to request a data transfer. The DMA request signals indicate:
z
Whether a single word or a burst (multi-word)transfer of data is required
z
Whether the transfer is the last in the data packet.
The DMA request signals to the DMA controller for each peripheral are as follows:
DMACxBREQ :
Burst request signal. This executes a programmed burst number of words to be transferred.
DMACxSREQx:
Single transfer request signal. This executes a single word to be transferred. The DMA controller
transfers a single word to, or from the peripheral.
Note:
If a peripheral transfers only bursts of data, it is not mandatory to connect the single transfer request signal. If
a peripheral transfer only single word of data, it is not mandatory to connect the burst request signal.
DMA response signals
The DMA response signals indicate whether the transfer initiated by the DMA request signal is complete. The
response signals can also be used to indicate whether a complete packet has been transferred.
The DMA response signals from the DMA controller for each peripheral are as follows:
DMACxCLRx:
DMA clear or acknowledge signal.
DMACxTC:
DMA terminal count signal.
The
DMACxCLRx
signal is used by the DMA controller to acknowledge a DMA request from the peripheral.
The
DMACxTC
signal is used by the DMA controller to indicate to the peripheral that the DMA transfer is complete.
Note:
Some peripherals do not require connection to the DMA terminal count signal.
Transfer types
The DMA controller supports four types of transfer:
z
memory-to-peripheral
z
peripheral-to-memory
z
memory-to-memory
z
peripheral-to-peripheral.
Each transfer type can have either the peripheral or the DMA controller as the flow controller. Therefore there are
four possible control scenarios.