casex	STAT[1:0]	OVF	output	NEXT[1:0]	LED_BUILTIN_t	TPRD[23:0]	comment
	T0	0		T0	0	TPRD_S	LED on 150ms
	T0	1		T1	1	TPRD_S	got overflow, move to T1
	T1	0		T1	1	TPRD_S	LED off 150ms
	T1	1		T2	0	TPRD_S	got overflow, move to T2
	T2	0		T2	0	TPRD_S	LED on 150ms
	T2	1		T3	1	TPRD_L	got overflow, move to T3
	T3	0		T3	1	TPRD_L	LED off 550ms
	T3	1		T0	0	TPRD_S	got overflow, move to T0
default				T0	0	TPRD_S	
							
ff LED_BUILTIN clk LED_BUILTIN_t !rst_n 1'b1							
ff STAT[1:0] clk NEXT[1:0] !rst_n T0							
							
module blink_fsm							
							
input\tclk;							
input\trst_n;							
input\tOVF;							
output\tLED_BUILTIN;							
output\t[23:0]\tTPRD;							
							
							
// state code							
parameter\t[1:0]\tT0=2'h0;							
parameter\t[1:0]\tT1=2'h1;							
parameter\t[1:0]\tT2=2'h2;							
parameter\t[1:0]\tT3=2'h3;							
// timer period							
`ifdef\t\tSIMULATION							
parameter\t[23:0]\tTPRD_S=24'd15 - 24'd1;							
parameter\t[23:0]\tTPRD_L=24'd55 - 24'd1;							
`else\t//\tSIMULATION							
parameter\t[23:0]\tTPRD_S=24'h36EE80 - 24'h1;\t// 150ms for clk=24MHz							
parameter\t[23:0]\tTPRD_L=24'hC96A80 - 24'h1;\t// 550ms for clk=24MHz							
`endif\t//\tSIMULATION							
							
reg\t\t[1:0]\tSTAT;							
reg\t\t[1:0]\tNEXT;							
reg\t\tLED_BUILTIN;							
reg\t\tLED_BUILTIN_t;							
reg\t\t[23:0]\tTPRD;