USB CDC Serial Port

longTimer · ‎2011-06-10

Posted on June 10, 2011 at 21:14

Hi,

I am concepting a new design that has to communicate using USB. I have a pivitol question. Is it possible to implement a USB interface that emulates a PC COM port that will install under Windows without having a device specific '.INF' file? It looks like a device with a CDC class and an ADM subclass should install, but, it hasn't worked yet.

Also, does anyone know of some example code for a CDC 'USB to Serial' device. I would like to compare my code with a working example.

Thanks,

#install-virtual-com-port-driver-from-http://www.st.com/stonline/stappl/resourceselector/app?page=res #hi

longTimer · ‎2011-06-13

Posted on June 13, 2011 at 20:25

I have a STM3210E-EVAL board. Got and compiled the example code for Virtual com port. No display. Bad USB install in Windows.

Any suggestions? Thanks.

alok472 · ‎2011-06-17

Posted on June 17, 2011 at 15:57

Do you see a Yellow mark in Device Manager on connection ? Did you install Virtual COM Port driver - Release 1.3.1 available on Web ?

vikas_sinha75 · ‎2011-07-05

Posted on July 06, 2011 at 07:40

Hi,

For this you can use the USB to Virtual Com Port example. The firmware example for this is available at

http://www.st.com/stonline/stappl/resourceSelector/app?page=resourceSelector&doctype=FIRMWARE&ClassID=1734

STM32F101CB

http://www.st.com/internet/com/SOFTWARE_RESOURCES/SW_COMPONENT/FIRMWARE/um0424.zip

STM32F10x and STM32L1xx USB full-speed device library

3.3.0

. Modify the code (GPIO settings etc for Pull up pin of USB) as per your requirement and run it on your board. Then check the status of device in device manager if shows a yellow mark under com port catagory then your board has not been configured properly. For this you have to install the V Com Prt driver available at

http://www.st.com/stonline/stappl/resourceSelector/app?page=resourceSelector&doctype=SW_DRIVER&ClassID=1734

vikas_sinha75 · ‎2011-07-05

Posted on July 06, 2011 at 07:49

Hi,

install Virtual Com port driver from

http://www.st.com/stonline/stappl/resourceSelector/app?page=resourceSelector&doctype=SW_DRIVER&ClassID=1734

. If problem still persists simply replace the VID and PID fields from inf files (generally available in C:\Program Files\STMicroelectronics\Software\Virtual COM Port Driver) with the VID and PID provided in your usb_desc.c file under device descriptor.

Hope it will work.

swapnilkhorate · ‎2012-01-08

Posted on January 09, 2012 at 08:35

I am using Ubuntu for development and using arm-none-eabi-gcc. I would like to know if Virtual com port driver for linux is available. The driver you have given is only for windows.

Thank you.

sudipto · ‎2012-10-03

Posted on October 03, 2012 at 13:11

Hi Vikas,

Thanks for the guidance that you have provided.

As per your suggestion, we downloaded the Virtual Com port driver ver 1.3.1 and installed it. We were still getting the yellow mark in the device manager.

We then tried to match teh VID and the PID as per our usbd_desc.c file. But still we are not able to identify the device as a virtual COM port.

We are using STM32F407VE controller on our target system and Windows 7 32 bit system.

Any help would be appreciated.

Andrew Neil · ‎2012-10-03

Posted on October 03, 2012 at 14:30

''a USB interface ... that will install under Windows without having a device specific '.INF' file?''

HID ?

sudipto · ‎2012-10-03

Posted on October 03, 2012 at 15:23

I am using CDC driver on my target and when i am connecting this device to my system, it says that Unknown device under Universal Serial Bus. What i had expected is that my device woul dbe populated under the ''Ports'' section in my device manager as a virtual COM port.