Here’s an example Verilog code to implement a 4-bit ring counter circuit:
module ring_counter (output reg [3:0] count, input clk);
always @(posedge clk) begin
count <= {count[2:0], count[3]};
end
endmodule
This code defines a module called "ring_counter" that implements a 4-bit ring counter. The output "count" is a registered output that represents the current state of the counter. The input "clk" is the clock input that controls the counter operation.
The "always @(posedge clk)" block is a sequential logic block that updates the "count" output based on the clock signal. On every positive edge of the clock, the counter shifts the current contents of "count" left by one bit and inserts the most significant bit at the least significant bit position. This creates a circular shift that gives the impression of a rotating ring.
Note that this Verilog code assumes that the "count" output and the "clk" input are both 1-bit signals. If you want to use multi-bit signals, you would need to modify the code accordingly. Additionally, this code implements a rising-edge triggered counter. If you wanted to implement a falling-edge triggered counter, you would need to modify the code accordingly.