I am trying to understand counters. Can anyone of you clarify me about terms (Divide by N) and Modulo(N) used in counter? What exactly it means?
A Divide by N counter implies that it divides the input clock frequency by N ie; if you cascade four flip-flops then, the output of every stage is divided by 2, if you are taking the output from the 4th flip-flop, then its output frequency is clock frequency by 16 (2^4).
Example: take a look at the timing diagram of a 3bit counter
A modulo N counter does the same thing as above and is also used as an alternate definition which implies that the counter counts N states.
Example: If a MOD-10 counter counts 10 states ( 0000 - 1000 )
I think simple answer is this
A counter which is reset at the Nth clock pulse is called Mod N counter or Divide by N counter.
found it here