05-18-2012 01:46 AM
I have data encoded as 5 MHz (200ns) pulses. So, every 200 ns, I will get short pulses of 5ns duration (if data transmitted is 1) or no pulse (if data transmitted is 0). This data is transmitted via the SMA connector (C9) on the Spartan 3E starter kit, passes through some external circuitry (communication circuit) and is received back to the FPGA. I want to test if the data transmitted is same as data received and display the error on the LCD.
So, what pin on the FPGA kit should I use as an input pin in order to detect the 4ns-5ns pulses every 200ns?
05-18-2012 07:38 AM
I would route the signal to a global clock input. That way if you want to sample the pulses
by toggling a flip-flop when a pulse arrives you will be able to easily route the signal to a BUFG.
If you instead try to sample the input, you would need a pretty high speed sampling clock to
avoid missing pulses. In any case you can use a global clock input pin even if you decide to
sample the signal on another clock.