4bit binary counter

< Function description >

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.