DM6446 EVM usb port can't connect USB to UART converter

Have you enabled kernel support for serial gadget:

Device  Driver ->  USB Support -> USB Gadget ->

                                USB peripheral controller

                                    <X> Inverntra (M) USB peripheral

                                <M> USB Gadget driver

                                <M> Serial Gadget

Also, did you set J7 jumper on DM6446 EVM to enable slave USB mode.

I did as you said, however, if DM6446 EVM works in host mode, the issue still exists. if i let DM6446 EVM to work in slave mode, the DM6446 can't recognize USB devices. can you tell me what's the difference betweet DM355 and DM6446 for the USB part?  The usb port works well in DM355 EVM.

Thanks

I am not sure if the silicon has any significant differences, but the external circuitry and thus the kernel drivers are different.  For example, DM6446 EVM cannot support OTG without some hardware mods, while DM355 I believe can.

I do not recall anyone ever doing a master USB implementation of a serial port;  a slave (or gadget) implementation is more popular, hence my previous post suggestion.

I replaced the USB driver of DM6446 EVM by the one of DM355 EVM, it doesn't make difference.  It seems DM6467 EVM has the same issue of USB port as DM6446 has.

Can you tell us a little bit more about your setup; for example, what are you using at the end of the UART connector?  How is the communication flowing across this device (PC (UART) to EVM(USB))?

The main difference I could think of is the OTG support on DM355; hence I wonder is DM355 EVM is really working as a master or slave USB device...

The Current connection is: I have one USB_UART adaptor connect to USB of EVM, the USB UART will connect to the UART of PC. I use these two UARTs to communication each other. When I connect the USB UART to DM6446 EVM, the EVM reports VBUS Error when it works in master mode. if I use the separate power supply to USB UART, it works. However, when i use the usb hub to connect to the usb port of DM6446 EVM, then i connect USB UART to usb hub. but the USB UART doesn't work well.  However, I did the samething to DM355 EVM, it works well.

Between DM644x and DM355 USB behavior would typically be the same.  Are you using different LSP versions on DM644x and DM355 platforms?

    For DM355 and DM6446 EVM, I am using the same version of LSP and kernel: LSP_PSP_01_20_00_014.  I downloaded them from Ti website: DM355_1_30_01 and DM6446_1_30_01.