Serial communications data path with optional features

Integrated circuits compliant with a serial communications protocol with optional and adjustable features are provided. Tools for designing such circuits are also provided. The protocol supports different data transmission modes such as streaming data and packetized data. A regular data port and priority data port may be provided so that priority data may be nested inside regular data during transmission. Various levels of data integrity protection may be provided. If no data integrity protection is desired, a user can opt to omit data integrity protection from a given integrated circuit design, thereby conserving resources. If data integrity protection is desired, the user can select from different available levels of data integrity protection. Data may be multiplexed using user-defined data channels.