As the field of hybrid electronics continues to integrate novel materials, there are many new emerging fields in the wearables industry with many new conceptualized applications being developed. Textile electronics is one example that focuses on developing functional fabrics with seamlessly integrated electronics, and there is a great need for developing new design guidelines for this field. For example, the development of models for signal integrity validation is critical, especially for implementing established communication protocols. I2C is not typically concerned with signal integrity given its low speed and wide performance margins, however for a fabric bus implementation, there are many considerations to take that are often negligible in traditional rigid applications. These include, capacitive loading of signals, signal order, crosstalk, and pull-up resistor identification.
In this work, the I2C communication protocol is analyzed, and performance criteria is developed for meeting the I2C standard. Several timing and electrical factors are explored to identify probable failure modes and to define bus constraints to help in the design and development of fabric I2C busses. In addition, manufactured fabric busses are performance tested and characterized. Through this effort, NextFlex has identified the challenges, and developed design technique recommendations for minimizing crosstalk and parasitic capacitance in developing I2C compliant fabric busses.
