Handshaked Transfer

[joshua william powell]

I have a high speed application wherein I use handshaking to read
data from a device. The REQ pulses sent by the device to the DAQ board
(an AT-DIO-32F) are TTL high .5 microsecond duration square pulses. These
signals are currently capable of triggering the computer, so I can get the
data I need. However, the device does not want to accept the ACK pulses
for some reason. Whenever I try to use them, the device just sits and
won't send data. My question is, can the board read the data fast enough
to make the ACK pulses irrelevant? The device waits another .5
microseconds after the END of the REQ pulse before it starts looking for
more data and latch to the buffer. If the DAQ board can read within the
first .5 microseconds while the
REQ signal is still high, the device will
keep the data on the buffer, guaranteed....or as guaranteed as it gets. 🙂
In the manual for the board it says "REQ to DRDY in leading edge
mode" is a maximum of 225 ns. Then it says "start of read or write to
DRDY inactive" maximum 240 ns. They never say how long it is from the
beginning of DRDY to the read or write, though. The only other piece of
information that seems to address this is "input data valid after REQ"
must be at least 120 ns. From how I interpret it, it seems like it could
take a maximum of about 620 ns. Does anyone out there have experience
with exactly how long it takes to read the data? I am not exactly sure
how to read the timing diagram.
If it reads within that microsecond, I don't even really need the
ACK pulse for the device, because it waits on it's own for that
microsecond. Thank you.

Josh