Tracii XL cannot operate without a reference voltage. The effects are that no I2C communication is possible. If you look at the SDA and SCL lines with an oscilloscope, you can see decreasing voltages which result in incorrect transmission. This is not a bug of Tracii XL - this is really a feature! It allows you to connect Tracii XL to I2C systems with voltages from 1.2 to 5.5 Volt without the need for Audrii. That means that your system needs to supply the reference voltage as Tracii XL does NOT do this (as a note: Tracii 400 does supply 5V and needs Audrii for different voltages).
So, for your system, you just need to apply your reference voltage to the VCC line of the bus. Itīs as simple as that.
