Need PCI Card for Low Freq TTL Control Signals


Thread Starter

Randy Parker

Our Red Hat Linux 6.2 computer gets control signals from a television studio automation system. I need a better way to receive these control signals on a PCI card.

We are currently using a ComputerBoards PCI-INT32 card, for which we wrote our own device driver. The driver interrupts on a state change in any of 16 control lines, as opposed to polling the device register. The only problem is that the
card is too damn sensitive!

We've added an external low pass filter to each control line to eliminate some noise which might otherwise give us a false signal. The CMOS-based card (Zilog 8536) responds to pulse widths as short as 150 ns. Our signals have a minimum
width of 250,000,000 ns. In fact, the studio control signal is so crappy that we've had to add 500 ms of "software debounce" to protect against switching noise.

We'd like to eliminate the external low pass filters by finding a "Digital IO" card that is better suited to our low-frequency TTL application. Ideally, a PCI board with an interrupt-based Linux driver available, or one for which a driver can written as easily as the Z8536.

Please copy replies to "[email protected]", as I am not a list regular.

Randy J. Parker
STAR XL Project Mgr
The Weather Channel
Atlanta, GA

Johan Bengtsson

Can't you make a software filter instead of changing the hardware? I mean if you have written your own driver it shoulb e fairly easy to make a software filter ignoring too fast signals.

/Johan Bengtsson

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