Could you give me some advice or point me in right direction?
I need accurate time/tick counter synchronized by GPS PPS synchronization signal.
I have got S.E.A. GPS cRIO Module which generate PPS signal to FPGA backplane. PPS signal rising edge precisely indicate the start of second.
When I measure number of ticks from 40MHz FPGA Onboard clock during one (PPS) second then number of ticks is not 40,000,000 ticks but something like 39,999,800 ticks.
I want measure accurately time between rising/falling edges of Digital signals. Because 40MHz FPGA onboard clock are drifting I can not use it.
How could I implement my own ticks counter witch will be tided with GPS PPS signal?
I don't expect that I could tune 40MHz FPGA on board oscillator.
Should I create my own counter which will increase counter by value 1.000,005 (40,000,000/39,999,800) every tick and this counter will run in Timed Loop (time base 40MHz FPGA onboard clock). Increment value (1.000...) will be updated every second depend on PPS vs FPGA clock drifting.
My configuration: cRIO-9025, cRIO-9116, S.E.A. GPS+ cRIO module, high speed DIs NI 9402, RT/FPGA LabVIEW 2011
Looking forward to hearing form you.
Peter
