Errors when starting the library with USB device already connected

[andreavalle]

Hello Bert,
I'm testing your library with the loopback code on a ESP32-S3 connected to a M-Bus USB interface implementing a CH341 chip (PID=0x7523).
Everything seems to work fine, but only if I connect the USB device to the OTG port after booting the ESP32 program. Instead, if the ESP32 starts with the USB device already connected to it, I get the following errors, with the last 5 lines that keep repeating:

E (3085) cdc_acm_ops: cdc_acm_host_line_coding_get(25): line_coding_get function not supported
E (3386) USBH: EP with 130 address already allocated
E (3386) USB HOST: EP allocation error ESP_ERR_INVALID_STATE
E (3387) USB HOST: Claiming interface error: ESP_ERR_INVALID_STATE
E (3391) cdc_acm: cdc_acm_start(191): Could not claim interface
E (3397) cdc_acm: cdc_acm_host_open(621): 

Any idea of the problem and on how to avoid it?

Thanks
Andrea

[bertmelis]

Which tool you use to build your program? Did you disable USB and CDC on boot?

I have to be honest, I didn't dig deep into the workings of the underlying libraries.

[andreavalle]

I use the Arduino IDE 2.3.6 with ESP32 3.3.4.
USB CDC on Boot is Disabled.
What about the "USB Mode"? Should I use "Hardware CDC and JTAG" or "USB-OTG (TinyUSB)"?

[bertmelis]

I'd say USB-OTG.

[andreavalle]

Doesn't seem to change

[bertmelis]

How did you actually connect the USB interface?
And how are you getting the log statements from the ESP? Make sure there is no interference here.

[andreavalle]

I'm using an ESP32S3-Wroom-1 like this: https://www.amazon.it/Diymore-DevKitC-sviluppo-Bluetooth-saldati/dp/B0CYZVQR27
It has 2 USB-C ports, the left one is configured as USB-OTG and the right one as USB-UART. The logging comes from normal Serial.print statements via the USB-UART port connected to the computer.
The interface is like this: https://it.aliexpress.com/item/1005008279574548.html
It has a USB-C port and I've connected it to the USB-OTG port of the ESP32.

I modified your code to use the USBHostSerial library to drive the USB Host port as a serial I/F.