DUT USB connection - sonyxperiadev/CDB-Assist GitHub Wiki

###USB cable The USB cable used between the CDB Assist and the target device (DUT) is a bit non-standard, it has to be a straight-through cable with all five wires connected without any internal grounding of the ID pin. We've been using the RR-MCBMCB-18G5 cable with great results. Having all five wires connected is important when you want to switch between host and device mode on the fly or simply want to utilize the ID pin for something like a UART connection for instance. To minimize cable voltage drop the shortest cable is recommended.

###Voltage levels The VBUS path to/from the DUT USB connector is designed to handle not only the normal USB standard 5V supply but also the QC QuickCharge voltage levels up to 20V (with a max current of 2A). Current flowing IN to the DUT is reported as positive, current flowing OUT of the DUT is reported as negative. ID pin and D+/D- pins are designed to handle the USB data signaling voltages (up to 3.3V).

###USB multiplexing The USB D+/D- lines are routed through a high-speed capable USB switch. The MUX has five states in total including an isolated state where the data lines are tri-stated. This makes it possible to make the USB connection to the DUT behave as if the cable is completely disconnected. As the fourth switch position routes DUT D+/D- to the PSoC any digital function can be performed in firmware (analog is not supported on the SIO pins used).