Using USB to UART Bridge Controller with Windows CE USBUART Driver - KBA86255

Version: *A

 

Question:

What are the prerequisites of using the Windows CE USBUART driver with the USB to UART Bridge Controller? What is the COM port number assigned by the driver? Will this driver load without using the Cypress Vendor ID (VID) and Product ID (PID)?

 

Answer:

Your operating system must include the Microsoft UHCI/OHCI/EHCI driver and Microsoft USB stack module “USBD”. The Cypress USBUART virtual COM port driver depends on the Microsoft USB stack, and noncompliance to this architecture can severely affect the functionality of the USBUART driver. 

The current implementation takes the next available COM port number and assigns it to the Cypress USBUART driver. This avoids any COM port number conflicts. However, you can change the registry setting to use a fixed COM port number. For more information, refer to Windows CE documentation

You can follow these steps to load the driver without using the Cypress VID and PID: 

  1. Change Windows registry settings to reflect the new VID and PID.
  2. Add and set a new global environment variable called BSP_NO_CYP_VID. Recompile the source and build the Windows CE image.