23. Open-Drain I2C SDA line

Design i2c_line to model an open-drain I²C SDA line using tri1.

• Module: i2c_line
• Input: drive_low (1 = actively pull line low, 0 = release)
• Output: sda (idle high when undriven)

⚠️ Note: tri1 is not supported by current version of synthesizer.