USB Host: number of endpoints limited to 8

clydeps
Posts: 8
Joined: Tue Jun 14, 2022 12:17 am

USB Host: number of endpoints limited to 8

Postby clydeps » Mon Aug 26, 2024 1:52 am

I'm trying to talk to a 4 port usb-serial chip, which needs 9 endpoints (control plus 2 each for each port, i.e. 4 interfaces.)

When I try to claim the fourth interface, it fails with NOT_SUPPORTED error, and I believe this is due to the number of channels available being only 8, as defined in components/hal/include/hal/usbh_hal.h:

Code: Select all

#define USBH_HAL_NUM_CHAN                   8
Firstly, am I right in my assumption that this is the limiting factor?
Secondly, am I to right assume that the only work-around would be to use a custom version of the SDK?

clydeps
Posts: 8
Joined: Tue Jun 14, 2022 12:17 am

Re: USB Host: number of endpoints limited to 8

Postby clydeps » Mon Aug 26, 2024 2:41 am

Ah, it seems this is a hardware limitation of the ESP32-Sx chips.

chegewara
Posts: 2362
Joined: Wed Jun 14, 2017 9:00 pm

Re: USB Host: number of endpoints limited to 8

Postby chegewara » Mon Aug 26, 2024 10:09 am

esp32 P4 should have EP0 + 15 endpoints, at least according to very old datasheet you can find on internet.

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