23. Open-Drain I2C SDA line

How do you plan to solve it?

• An I²C SDA line is open-drain, meaning devices can pull it low but never drive it high.
• Using tri1 declares the wire with a default pull-up to logic 1 when undriven.
• When drive_low = 1, the module actively drives 0 onto the line.
• When drive_low = 0, the module outputs high-impedance (Z), releasing the line.
• The result correctly models I²C behavior: wired-AND, idle high, pull-low only.

/*Write your code here*/
module i2c_line(
    input  drive_low,   
    output tri1 sda     
);
    assign sda = (drive_low) ? 1'b0 : 1'bz;
endmodule