- From: Caleb Tennis <caleb_at_aei-tech.com>
- Date: Fri, 11 Oct 2002 08:05:05 -0500
> I'm planning to use the GPCT features of NI PCI cards > (6023E to be specific) and found a number of routines > in the ni_mio_common.c driver. These routines probably > cover all I need for now, but since the documentation > on this part is a bit scarce (or maybe I just can't find it:-) > I'd be happier reading someone else's suggestions/directions/ > application code rather than diving into the source... I use the GPCT on this very card to measure frequency. At first I was using the internal timer (20 Mhz), telling the GPCT to start, then stopping on the trigger of my input frequency. For some reason, I didn't have a lot of luck with that method. Now I have it set up to directly measure the number of pulses it sees in 1/10 of a second. I can use that to determine my frequency, and that works pretty well. I'd be happy to send you code snippets if that would be helpful. My biggest problem, and one that still plagues me, is false triggering. Unfortunately, my equipment is being used in an environment where there is a lot of electrical noise, and there are times that I pick up ground noise and it impacts my frequency measurement. We're still trying to figure out the best "buffer" circuit to suppress that, but once in a while it still occurs. Caleb
Received on 2002-10-11Z12:05:05