User`s guide

42 • Operation Theory
As the data output in the internal clock mode, the DOREQ signal could be use
as the output strobe to indicate the output operation to the external device. The
timing diagram of the DOREQ is shown as follows:
DOREQ as output data strobe
4.11.2 Digital Output DMA in Handshaking Mode
For digital output, through DO-REQ output signal and DO-ACK input signal,
the digital output can have simple handshaking data transfer.
The operations sequence of digital output in handshaking mode are listed:
1. Define the input configuration to be 32-bit, 16-bit or 8-bit data width.
2. Enable or disable the active terminators.
3. Define the output clock mode as handshaking mode. Connect the
handshaking signals of the external device to output pin DO-REQ and input
pin DO-ACK.
4. Define the starting mode to be NoWait, WaitTRIG, WaitFIFO, or WaitBoth
5. Digital output data is moved from PC’s system memory to output FIFO by
using bus mastering DMA.
6. After output data is ready. A DO-REQ signal is generated and sent the
output data to the external device.
7. After a DO-ACK signal is gotten, the step 6 and step 7 will be repeated again