what ports are used for handshaking signals?

[Joshua_Lamorie]

I want to use Handshaking Digital I/O on an AT-MIO-16DE-10, and I want to know if there are extra digital I/O lines used for this, or if there are independant handshaking connections. I can't seem to find any documentation which warns that you can only get 7 bits out of a port if you use handshaking. Or you can only use ports 2,3,4 because port 0 is used for the handshaking signals.

Any hints would be appreciated.

[Erin_B.]

The AT-MIO-16DE-10 has 2 digital chips on it. Port 0 is provided by the DAQ-STC chip. Ports 2, 3, and 4 are provided by the Intel 8255 chip. This chip is capable of handshaking. When it is used for handshaking, ports 2 and 3 are the data ports, and port 4 is used to handshake with the external device. For more information, you can refer to:

http://zone.ni.com/devzone/conceptd.nsf/webmain/667F2B831AFCBA6F86256802007B8CC9?OpenDocument

Regards,
Erin

[Joshua_Lamorie]

Great, actually, I found this information, and would like to re state my question. Now that I know what ports I should be using (this is described in detail in the hardware manual for the E series), I would like to see some definite information about what I must do in my external device to make use of these signals.

I'm a little confused by some comments in the documentation that some of the facilities of Port C (on the 8255) are only avialable if I use register level commands (as if using the parallel port). If I use the DIG_Prt_Config and set to handshaking (input) on a port, then I assume I set up my external hardware as if Port C was in Mode 1(input), and then follow the timing described in the E Series manual.

It's just a shame that everything o
n the PC side is well described, but there are no application notes that I can find about building an external device that can use the handshaking signals.

If 'you' (anyone) can confirm what my assumptions, or point me in the right direction, I would appreciate it greatly.

Thank you.

Joshua

[Erin_B.]

Calling DIG_Prt_Config and configuring the board for mode 1 will set up the chip for input mode 1 and the corresponding lines for port C will be used as depicted in the timing diagram for that mode. Your external device must be able to interpret the timing on those lines to output data accordingly. The Intel 8255 PPI handshaking protocol is a fairly common protocol.

There is some functionality of port C that is not exposed through NI-DAQ like the ability to use the available I/O lines on Port C during handshaking. Those lines have to be accessed with register level programming when a simulataneous handshaking operation is taking place on one of the other ports. However, this is a corner case and the majority of the functionality of the chip is expose
d through NI-DAQ.

Regards,
Erin