HC-SR04 (ultrasonic sensor) verilog code help

Hi, i took help from a vhdl code (i am not familiar with it though). Here's the link to the vhdl code:

https://github.com/xesscorp/xula/blob/master/fpga/xula_lib/hcsr04.vhd

I know i'm missing something. I am a verilog beginner. Hope you can help.

Here's the code I've written so far:

'timescale 1 us/ 1 us

module sensor (trig, dist, clear, led, clk, echo);

output trig, dist, clear, led;

input clk, echo;

reg [3:0] timer;

always @ (posedge clk)

begin

timer <= timer +1; //timer will start soon as positive clock pulse is detected

if timer = 10; //It takes 10 us to send pulse from sensor

trig = 1; //then,trig is high after 10us

else if echo; //when echo is high, dist counting starts, trig goes to low, led turns on

begin

dist <= dist + 1; //echo pulse width

trig <= 0;

led = 1;

end

if dist <= 38; //max echo back time = 38 us without obstacles

begin //then everything will be back to intial condition

clear =1;

dist <= 0;

timer <=0;

led <= 0;

end

end

assign dist = dist * 340; //multiplying with speed of sound in air

endmodule