• State Not Answered
  • Locked Locked
  • Replies 12 replies
  • Subscribers 21 subscribers
  • Views 3788 views
  • Users 0 members are here
2025 survey

We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.

Options
Related
How was your experience today?
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

USB CDC-ACM function class

F D

Hi,

I use a modified version of Keil's USB CDC-ACM function class implementation. It works really well but I am having a problem in the way I am using it.
I use the virtual COM-port to connect as a modem to the host PC.
My target connects through PPP to the USB CDC-ACM input/output. This allows me to create multiple sockets for multi-channel TCP/IP communication. This creates the problem! With increasing communication throughput my application showes signs of instability.
I am looking for a way how I could limit the data throughput at the USB device level.
Could someone provide me with an feasable example of how to achieve this?
I appreciate your help - thank you!

-Frank

Parents Reply Children
  • 0 in reply to F D

    "but never succeeded in reading FE bit status"

    I mistakenly use WrCmd() in above posts. It is replaced to RdCmdDat() as follows.

    a) bulk OUT EP
- Check the FE bit of "Select Endpoint" command, if the EP buffer is empty, return
- - WrCmd( CMD_SEL_EP(EPAdr(CDC_DEP_OUT)) ); if ( CMD_DATA & EP_SEL_F == 0 ) return; // - wrong


    if ( RdCmdDat( CMD_SEL_EP(EPAdr(CDC_DEP_OUT)) ) & EP_SEL_F == 0 ) return;

    b) bulk IN EP
- Check the FE bit of "Select Endpoint" command, if no empty EP buffer, return
- - WrCmd( CMD_SEL_EP(EPAdr(EPNum)) ); if ( CMD_DATA & EP_SEL_F != 0 ) return; // - wrong


    if ( RdCmdDat( CMD_SEL_EP(EPAdr(CDC_DEP_IN)) ) & EP_SEL_F != 0 ) return;

    Tsuneo

  • 0 in reply to Tsuneo Chinzei

    Hi Tsuneo,

    thank you for your example.

    - Frank

  • 0 in reply to Tsuneo Chinzei

    Hi Tsuneo,

    you look like very skilled person in discussed area. I have found a different post (probably older and thus closed already - I can't reply there):

    http://www.keil.com/forum/docs/thread12298.asp

    It's regarding the composite virtual COM ports under M$ (related to usbser.sys). I'm trying to start uderstanding the CDC/ACM and would like to bring up more VCOMs on one device (LPC2368) with one (default, non-vendor specific) driver. You wrote you was testing it via IAD and/or multiple CDCs.

    Do you have any results from this?
    Is there any resource/example you could point me to or provide to speed up my understanding in this area?

    Thanks.

    Regards Pavel