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CCS/tm4c123gh6pm: usb_dev_serial.c from tm4c1294 and am335x

michael yang
Intellectual 680 points
Part Number: TM4C123GH6PM

Tool/software: Code Composer Studio

HI TI,

I am working on usb_host_cdc for tm4c123xgl following e2e.ti.com/.../, which is now able to send to / read back data from test equipments.

I have other evaluation boards, such as tm4c1294xl and am335x starter kit. Since both contain usb_dev_serial.c in tivaware and starterware packages respectively, I setup tm4c123xgl as USB host cdc connecting to other boards as USB device serial. (similar to https://www.keil.com/pack/doc/mw/USB/html/host_cdc_tutorial.html///) However, to my surprise, they cannot communicate to each other. Am335x screen shows "waiting for host...", and tm4c123xgl declarers "unknown USB connected".

Then I directly connected tm4c1294xl and am335x starter kit to a PC. Putty terminal demons usb_dev_serial runing smoothly.

I am wondering

1. whether there is a difference between cdc and serical, or

2. as USB device, tm4c1294xl and am335x starter kit need external power supply. or

3. as USB host, tm4c123xgl cannot supply power to USB device.

Please advise, thanks in advance

Mike

  • 0
    TI__Guru*** 135355 points

    Hello Michael,

    I can't speak about what the AM335x kit would need power wise, or what the software would do with a Tiva Host.

    The TM4C123 LaunchPad should be able to provide USB power, but whether it can power another LaunchPad such as the TM4C1294 LaunchPad I am not sure of. You at least need to make sure the other LaunchPad is configured for USB power via jumpers (which should keep it from backpowering the ICDI).

    From a serial vs cdc perspective, the example you are referring to for the TM4C1294 I believe is the 'cserial' example - that is a composite device example and very different from what you need. I did make a CDC device example a while back which I can share, so give this one a try:

    1362.usb_dev_cdcserial.zip

  • 0 in reply to Ralph Jacobi
    Intellectual 680 points
    Hi Ralph,

    Thank you for the help.
    Looks USB host/device can only communicate within the same class.
    My usb_host_cdc is able to transfer data to your usb_dev_cdcserical on TM4C1294xl. While connecting to cdc_dev_cserial, message reads "unknown USB connected".

    Best

    Mike