for (i = 0; i < BIN_WIDTH; i = i + 1) begin // Shift left bcd_reg = bcd_reg[4*BCD_DIGITS-2:0], bin_reg[BIN_WIDTH-1]; bin_reg = bin_reg[BIN_WIDTH-2:0], 1'b0;
bcd = bcd_reg; end endmodule module tb_bin2bcd; reg [7:0] binary; wire [11:0] bcd;
module binary_to_bcd #( parameter BINARY_WIDTH = 8, // e.g., 8-bit binary input parameter BCD_DIGITS = 3 // 8-bit binary max = 255 → 3 BCD digits )( input wire [BINARY_WIDTH-1:0] binary, output reg [4*BCD_DIGITS-1:0] bcd ); integer i; reg [4*BCD_DIGITS-1:0] temp; reg [BINARY_WIDTH-1:0] bin;
bin2bcd #(.BIN_WIDTH(8), .BCD_DIGITS(3)) uut ( .bin(binary), .bcd(bcd) ); Binary To Bcd Verilog Code
// Add 3 to digits > 4 for (j = 0; j < BCD_DIGITS; j = j + 1) begin if (bcd_reg[4*j +: 4] > 4) bcd_reg[4*j +: 4] = bcd_reg[4*j +: 4] + 3; end end
always @(*) begin temp = 0; // Clear BCD accumulator bin = binary; // Local copy of input
initial begin $monitor("Binary = %d (%b) → BCD = %b (%d %d %d)", binary, binary, bcd, bcd[11:8], bcd[7:4], bcd[3:0]); binary = 8'd0; #10; binary = 8'd5; #10; binary = 8'd42; #10; binary = 8'd99; #10; binary = 8'd170; #10; binary = 8'd255; #10; $finish; end endmodule for (i = 0; i < BIN_WIDTH; i
: BCD uses only 0–9; combinations 1010–1111 are invalid. 3. The Double‑Dabble Algorithm The Double‑Dabble (or shift‑and‑add‑3) algorithm converts binary to BCD without division or multiplication, making it ideal for hardware implementation.
for (i = 0; i < BINARY_WIDTH; i = i + 1) begin // Shift left by 1: bring next binary bit into LSB of temp temp = temp[4*BCD_DIGITS-2:0], bin[BINARY_WIDTH-1]; bin = bin[BINARY_WIDTH-2:0], 1'b0;
module bin2bcd #( parameter BIN_WIDTH = 8, parameter BCD_DIGITS = 3 )( input [BIN_WIDTH-1:0] bin, output [4*BCD_DIGITS-1:0] bcd ); reg [4*BCD_DIGITS-1:0] bcd_reg; reg [BIN_WIDTH-1:0] bin_reg; integer i, j; for (i = 0; i < BINARY_WIDTH; i
always @(*) begin bcd_reg = 0; bin_reg = bin;
bcd = temp; end endmodule For a truly scalable version, use a generate loop or a for loop that iterates over BCD digits:
Here’s a comprehensive write-up on , suitable for a technical blog, documentation, or academic submission. Binary to BCD Conversion in Verilog 1. Introduction In digital systems, binary numbers are the native representation, but many human‑interface devices (like 7‑segment displays, LCDs, or real‑time clocks) require Binary Coded Decimal (BCD) format. BCD represents each decimal digit of a number by a separate 4‑bit binary code.
// Check and correct each BCD digit // (using blocking statements inside loop) // Digit 0 (least significant BCD digit) if (temp[3:0] > 4) temp[3:0] = temp[3:0] + 3; // Digit 1 if (temp[7:4] > 4) temp[7:4] = temp[7:4] + 3; // Digit 2 (for 3-digit BCD) if (BCD_DIGITS > 2 && temp[11:8] > 4) temp[11:8] = temp[11:8] + 3; // Add more digits if needed end