MUX Via Strapping Option

A hardware strapping (jumper setting) method can be utilized to change the expansion board configuration. It is important to note that the hardware configuration can conflict the BIOS setting when changing between the PCI-Express and USB3 pin configuration as the manual stuffing method does not provide dynamic board configuration. To facilitate the voltage level changes between module and connector, a level-shifter must be implemented on control signals CLKREQ, WAKE and PERST which shift their levels between 1.8V (module side) and 3.3V (connector side).

The diagram below offers an example that utilizes resistor stuffing options to connect one PCI-Express device or USB3 device.

 

Notes:
  1. Hardware based solution that supports either one USB3 or one PCI-Express based endpoint. A resistor stuffing selects which endpoint
    is physically connected (USB3 or PCI-Express).
     BIOS programs the compute module to support either USB3 or PCI-Express.
  2. Only PCI-Express Port 1 is a viable option; usage of Port 0 is not supported.
 
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