ADLINK cPCI-7300 - Manual (Page 51)

Operation Theory • 43
4.11.3 Digital Output DMA in Burst Handshaking Mode
The burst handshaking mode is a fast and reliable data transfer protocol. It
has both advantage of handshaking mode, which is reliable, and the
advantage of internal clock mode, which is fast. When using this mode, the
sender has to check the availability of receiver indicated by the DO-ACK signal
before it starts to send data. Once the DO-ACK is asserted, the receiver has to
keep the DO-ACK signal asserted before its input buffer becomes too small.
When the DO-ACK is de-asserted, indicating the receiver’s buffer has not
much space for new data, the sender is still allowed to send 4 data to the
receiver, and the receiver has to receive these data. The following figure
illustrates the operation of the burst handshaking mode:
The operations sequence of digital output in burst 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 as burst handshaking mode and decide the timer
pacer rate to be 20Mhz, 10Mhz, or the output of 82C54 timer 1.
4. Connect the handshaking signals of the external device to output pin
DO-REQ and input pin DO-ACK.
5. Define the starting mode to be NoWait, TrigWait, WaitFIFO, or WaitBoth
6. Digital output data is moved from PC’s system memory to output FIFO by
using bus mastering DMA.
7. After output data is ready. DO-REQ signals are generated and sent the
output data to the external device when the DO-ACK is asserted.