Two control pins on the HD3SS214 are responsible for selecting the incoming DP signal: Dx_SEL and AUX_SEL. Dx_SEL controls which high speed ports are selected. A low signal on Dx_SEL corresponds to Port A routed to Port C and a high signal corresponds to Port B routed to Port C. A slide switch is used to select the level for this signal. In an embedded application, this switch can be replaced by a GPIO signal from a microcontroller.

AUX channel is controlled by AUX_SEL. This pin configures the switch to route the incoming AUX signal to the outgoing AUX path, when AUX_SEL = 0 the AUXA channel will be routed to AUXC, when AUX_SEL = 1 the AUXB channel will be routed to AUXC. Figure 8-2 shows the selection circuitry.

Figure 8-2 AUX_SEL Schematic