VIM4 USB endpoint count on USB-C/OTG port?

VIM4
1

Which system do you use? Android, Ubuntu, OOWOW or others?

Android 11

Please describe your issue below:

How many USB endpoints are available on the VIM4’s USB device exposed through the OTG/Type-C connector?

2

@xavier,

The VIM4 Type-C interface does not support USB HOST. Cannot be used externally for expanding and connecting USB devices

3

Yes, I understand that the TypeC connector is only for exposing a USB device from the VIM4 (typically ADB/MTP or similar). I use the Linux USB Gadget driver and want to understand how many USB functions can coexist as a USB composite device in the VIM4. Therefore I need to know how many IN/OUT EP are supported by the hardware block (USB2 OTG in device mode). The documents I have available do not describe these details of the A311D2.

4

@xavier,

According to the USB protocol standard, the theoretical maximum number of devices that can be connected via a USB interface is 127.

5

My use case involves the Linux USB Gadget framework, where the VIM4 acts as a USB composite device (that is, a single USB device presenting multiple USB functions simultaneously, such as Ethernet-over-USB, serial, mass storage, etc.).

To correctly design and configure the gadget descriptors, I need to determine the maximum number of USB endpoints (both IN and OUT) supported by the hardware when the USB2.0 OTG controller operates in device mode. Each endpoint pair corresponds to a logical data channel, and their availability limits how many USB functions can coexist within one composite device.

Unfortunately, the public documentation for the Amlogic A311D2 SoC used in the VIM4 does not specify these low-level details — such as the total count of configurable IN/OUT endpoints, supported endpoint types (Bulk, Interrupt, Isochronous), or any architectural constraints of the USB2 OTG controller.

Could you please confirm:

  1. The exact number and type of available endpoints (beyond the mandatory EP0 control endpoint) supported in USB device mode by the USB2 OTG controller on the A311D2.
6

@xavier,

We have checked the relevant documents, but have not seen the relevant information for the time being. We will reply to you as soon as possible.

7

@xavier,

A311D2 otg as device： EP0 + 3 IN EP + 3 OUT EP 。

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8

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