VME-$\rm I^2C$

An interface between VME and $\rm I^2C$ buses is provided by the VME-$\rm I^2C$ board. As seen in the block diagram (fig. ), the functionality of this module is straight-forward. The VME bus is bridged to an $\rm I^2C$ bus master, followed by an opto-coupler and a bus extender.

Figure: Block diagram of the HEPHY VME-$\rm I^2C$.

An opto-coupler is used to connect $\rm I^2C$ signals of different voltage levels. This implies that the bus extender is powered by the remote repeater. Originally, the $\rm I^2C$ bus was intended for communication between components on a single board and thus has a limited line drive capability. Between a set of two extenders, the line currents are amplified to cope with the higher capacitive load and noise.