ADLINK cPCI-7300 - Manual (Page 41)

Operation Theory
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for the assertion of DI-ACK. If the external device follows the rule, there
would be no data lost due to FIFO overrun.
3. Handshaking: For the digital input, through DI-REQ input signal from
external device and DI-ACK output signal to the external deviec, the digital
input can have simple handshaking data transfer.
For the digital output, through DO-REQ output signal to the dexternal
device and DO-ACK input signal from external device, the digital output
can have simple handshaking data transfer
4. Burst Handshaking: This mode is available for both digital output and
digital input. If the digital output DMA use internal clock and the burst
handshaking mode is enable, the cPCI/PCI-7300A output data only when
DO-ACK is asserted. That is, the external device can control the data input
from the cPCI/PCI-7300A by asserting the DO-ACK pin when it is ready to
receive data.
The software driver functions of 5.6 and 5.7 are provided to setup the clocking
mode of digital input and digital output, respectively.
Notes: Due to the internal clock is based on 10MHz clock, some specific
sampling rate o r pacer rate cannot be generated by software, such as
9MHz. For digital input, users can use the external clock source.
However, for digital output, users should replace the default 40MHz
oscillator because the current version of cPCI/PCI-7300A does not
s upport external clock for digital output.
The frequency of external input clock cannot exceed 40MHz due to the local
bus timing requirement.
When users replace the default oscillator on board, the corresponding
frequency would be changed, for example, by replacement with
36Mhz oscillator, the internal clock selection would be changed to
18MHz, 9MHz, and 9MHz base timer output.
4.8 Starting Mode
Users can also control the starting mode of digital input and output by external
signals (DITRIG and DOTRIG) with the software programs. The trigger modes
includes NoWait, WaitTRIG, WaitFIFO, and WaitBoth.
1. NoWait: The data transfer is started immediately when a I/O transfer
command is issued.