The AS8221 provides an optimized host controller interface consisting of three low-active pins. The Enable (EN) and Standby (STBN) input pins for mode handling by the microcontroller and the Error (ERRN) out pin where system, chip failures or status information are signalled to the microcontroller. Signalling logic high on the Enable and Standby pin the device will enter NORMAL mode in case no fault condition is given and in this mode the device is fully operational meaning FlexRay communication is possible. Additionally a RECEIVE-0NLY mode is implemented, which can be accessed by the microcontroller where only FlexRay streams can be received in order to avoid unwanted disturbances on the FlexRay bus while listening to the bus traffic. In the low-power modes (STANDBY and SLEEP mode) very low power consumption is achieved.