File name

CNT4.nsl

Function

4bit synchronouse counter circuit.

– Asynchronous reset.

– Carry input

– Initial value load

– Count enable

– Carry output

I/O signal

PARAM_in[4]=Initial value.

LOAD_in=Load request.

ENB_in=Count enable.

CARRY_in=Carry input.

Q_out[4]=Data output.

CARRY_out=Carry output.

Specification

This code shown example of 4bit clock synchronous counter using 4bit F/F.At a ‘LOAD_in’ signal is asserted, ‘PARAM_in’ values are loaded to 4bit counter.Also, ‘ENB_in’ and ‘CARRY_in’ are asserted, counter is ‘+1′.A ‘CARRY_out()’ function output signal is asserted at 4bit register value’s status is all H(4′b1111′).

Note

NSL language style does not need to care a implicit CLOCK and asynchronous reset in source code.These signals are automatically generated by NSL synthesis tools.At ‘CARRY_in()’ function control signal is asserted, ‘Function [sigName]‘ block will be called.