Hi everybody!

I want to know how can i implement zero crossing detector using VHDL in FPGA. So i want to implement a digital constant fractional discriminator. The firt part provide a bipolar signal was implemented but i want to know how i can implement zero crossing detector in vhdl.


Thank you for your help!

 

You can't. Zero crossing is essentially an analog function, and VHDL has no concept of continuous analog values. Outside of the FPGA you could implement a window comparator with some hysteresis to indicate the zero crossing event. The DIGITAL output of the comparator can then be routed to the FPGA for further processing.

You could also have an analog to digital converter with a parallel output bus that would connect to FPGA inputs, but again that's not the same thing as doing it inside the FPGA in VHDL