toplev.abl

16V8例程,应用GEL16V8实现的振荡器,振荡频率为300k-20Hz

MODULE toplev

TITLE '8 bit Johnson counter'

"Performs an 8 bit Johnson or ring count synchronously.


"Inputs
	CLK,SYSCLR,RUN			pin;

"Outputs
	Q7,Q6,Q5,Q4,Q3,Q2,Q1,Q0		pin istype 'reg_d,buffer';



"Sets
	count = [Q7,Q6,Q5,Q4,Q3,Q2,Q1,Q0]; 	"Counter set.
	prev  = [Q6,Q5,Q4,Q3,Q2,Q1,Q0,!Q7];     "Counter set is fed from this set.
						"It is much easier to perform wide
						"operations such as counters or mathematical
						"functions by establishing signal sets.



Equations

	count.d = prev.q & RUN             "increment count if RUN
		# count.q & !RUN;          "hold if not RUN

	count.clk = CLK;
	count.ar = SYSCLR;

Test_Vectors ([SYSCLR, RUN]->count)
	cycle CLK (0, 30) (1, 30);
	wait   15; [1,0]->.X.;
	WAIT   30; [0,0]->.X.;
	WAIT   75; [0,1]->.X.;
	WAIT 1800; [0,0]->.X.;
	WAIT  240; [0,1]->.X.;
	wait 100;
END