23. Open-Drain I2C SDA line

How do you plan to solve it?

module i2c_line(
  input  wire drive_low,
  output tri1 sda           // tri1 = weak pull-up when undriven
);
  // Open-drain behavior: either pull low or release (Z)
  assign sda = drive_low ? 1'b0 : 1'bz;
endmodule