TM4C123GH6PGE: Question on USB endpoint usage when implementing multiple VCOM ports

Richard Chen75

Part Number: TM4C123GH6PGE

Hi all, when implementing a VCOM port, two endpoints are needed:

- One for control interface (In and Out)

- The other for Data interface (In and Out)

Does anyone know if the Control Interface can be shared when implementing multiple VCOM ports? In other words, the extra endpoints for the additional VCOM ports are needed for the data interface only? Or the control interface is per VCOM port therefore extra endpoints are required as the result?

I would appreciate any document or link on this regard.

Thank you!

Richard

over 7 years ago

0 Ralph Jacobi over 7 years ago

TI__Guru*** 135355 points

Hello Richard,

Honestly that boils down to more of a USB specifications question. While I do work with the USB stack a lot, I didn't develop it personally and don't know all the specifications regarding endpoints. Google might be your best bet, but I'll share with you my go to site when I need to figure out how the USB stack should be working: http://www.beyondlogic.org/usbnutshell

Just looking at the USB Descriptors portion, it looks like based on the structure that you'd need a control interface for each VCOM port. Though if all VCOM ports were under the same Interface Descriptor, then maybe you could get away with just one...?

0 Richard Chen75 over 7 years ago in reply to Ralph Jacobi

Intellectual 550 points

Thank you so much for the reply Ralph! I will do some more research on this regard.

Regards,
Richard

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TM4C123GH6PGE: Question on USB endpoint usage when implementing multiple VCOM ports