Generate a clock signal with pauses

[gfinder]

I have the NI-6259 multifunction DAQ card.

I would like to generate a digital clock with the following properties:

4MHz

After 1028 pulses, the clock pauses low for what would be 9639 pulses

and then the cycle repeats.

Is there a way to do this with my card?

[CKap]

Hello gfinder,

The PCI-6259 only has 2 counters with an onboard 80MHz clock. It is possible to generate a retriggerrable finite pulse train using these two counters following your specification, but your application demands a specific trigger which would require another counter for its generation. The trigger in this application would have to stay high for 1028 clocks cycles and then low for 9639 cycles. This is where the 6259 would be inadequate. I have attached an example program that generates retriggerable finite pulse train for your reference.

Chetan K

Application Engineer

NI

 

[gfinder]

Thank you Chetan. I did discover this example earlier today, and had made provisions for an external device to act as the trigger. Is there a similar example of this using the .NET api?

Also, is it necessary for the trigger to stay high for 1028 clocks cycles and then low for 9639 cycles as you say? The way I understood the example is that the trigger simply sets off the other two counters and it is only the trigger edge that matters. As I understand the process:

One counter generates a pulse train representing my clock.

A second counter counts to 1028 and stops the pulse train (I assume the pulse train generator's output is held low?)

An external trigger connected to a DIO pin resets the process. In my case, I would have that trigger occur at a fixed frequency from an external oscillator.

Thanks again for your assistance.

[CKap]

You were right about what you understood about the counter operations.

The trigger can either be defined for rising or falling edge and does not need to stay high for 1028 clocks. The only thing that matters are the edges. If you can generate an external signal which meets your requirements then that would be perfect.

I did come across a VC project that does a similar task. It should help you to head in the right direction.

Chetan K

Application Engineer

NI