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Questions about "virtual_com" USB CDC driver in MQX 3.6 & under CW10

Question asked by Michael Predko on Sep 6, 2010
Latest reply on Jun 12, 2012 by keith tang



I want to use the MQX USB driver configured as a CDC device.  I am using the "virtual_com" example app that comes with MQX 3.6.  I'm running on a M52223EVB. 


I am running virtual_com successfully on the M52223EVB and I am communicating with a Windows/XP PC using Tera Term.  I am not able to get a connection on a Windows 7 PC.  The goal for this product's USB interface is for the host app to be a single common Java program which runs on the different PCs listed below, opens and tests the different serial interfaces to find the product and start communicating with it. 


The product that this is being designed for will interface to:

- Windows PCs (various flavours XP, Vista 32 & 64 bit and Windows 7 32 & 64 bit)

- Macs

- Linux machines


My understanding is that a device that is set up as with the CDC interface provides this capability - but in the "virtual_com" folder, there is the "inf" folder which contains "fsl_ucwxp.inf" which must be installed on a Windows/XP machine for this to work - when I try it on a Windows 7 PC, I get "Unknown Device" in device manager and Windows 7 will not allow loading "fsl_ucwxp.inf". 


I have reviewed the "Universal Serial Bus Class Definitions for Communications Devices", Revision 1.2 which covers the CDC as well as the USB 2.0 specification and the class definition in virtual_com.c seems to be correct.  I have also searched the FLS forums and tried the trick suggested by BugMan to set the CIC_PROTOCOL_CODE value to AT_250_PROTOCOL as well as trying to associate "usbser.sys" to the "Unknown (USB) Device" in my Windows 7 machine as suggested in the uTasker documentation. 


Is there a way to set up a CDC driver that will appear as a serial port in whatever type of PC (defined above) without the need for special host .inf or .sys files?