bcd = temp; end endmodule For a truly scalable version, use a generate loop or a for loop that iterates over BCD digits:
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;
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
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. Binary To Bcd Verilog Code
bin2bcd #(.BIN_WIDTH(8), .BCD_DIGITS(3)) uut ( .bin(binary), .bcd(bcd) );
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;
: 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. bcd = temp; end endmodule For a truly
always @(*) begin bcd_reg = 0; bin_reg = bin;
// 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
// 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 BCD represents each decimal digit of a number
always @(*) begin temp = 0; // Clear BCD accumulator bin = binary; // Local copy of input
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;
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;