Sampling 500kHz 8 digital input with USB-6341/6343

[kris06]

I'm looking for a device that can be connected with an FPGA to sample 8 digital input at positive edge of an external clock running at 500kHz.

My question is, will USB-6341 or 6343 be capable of doing this?

Also, could I use MatLab to control this interface rather than LabView?

Thank you,

Kris

[Lemongrab]

Hello Kris,

I’m not sure what you mean when saying the device must be connected with an FPGA. Is this an NI device with a built in FPGA you are connecting to? Without knowing more information, it’s difficult to understand the context of your application and make recommendations.

That being said: To accurately measure the frequency of a digital pulse train, you will need to sample at a frequency greater than 2x the signal frequency for a 50% duty cycle. By sampling faster, you can more accurately detect rising/falling edges and measure frequency/pulse width.

For the best results, we recommend doing edge detection using a counter with counter tasks. Counters have access to reference clocks up to 80Mhz in general, and are hence more accurate and more responsive to the pulse train then a DI/O line will be. However, USB DAQ devices do not possess eight counters.

I recommend contacting our product advisors we can obtain a better understanding of your application, determine the performance you require, and recommend a suitable device. They can be reached throught the appropriate links here:

http://www.ni.com/advisor/