Method and apparatus for valid encoding

Aspects of the disclosure provide a circuit including an encoding circuit and a valid circuit. The encoding circuit is configured to encode data to be transmitted as signals on a data bus to satisfy a requirement that limits a number of bit transitions between consecutive transmissions. The valid circuit is configured to selectively corrupt the signals not to satisfy the requirement that limits the number of bit transitions between the consecutive transmissions to indicate whether the signals to be transmitted on the data bus constitute valid data or invalid data.