CDC-ACM Usb Host with FTDI adapter

[dontpostalot]

Hi

I'm trying to run the CDC-ACM Usb Host example with an FTDI RS485 adapter but my ESP32S2 fails to identify it as a serial device. The bDeviceClass, bDeviceSubClass and bDeviceProtocol fields of the device descriptor are all zero.

Code to list some of the fields:

Code: Select all

usb_device_handle_t current_device;
            // Open USB device
            if (usb_host_device_open(GetCdcAcm(), dev_addr_list[i], &current_device) != ESP_OK) {
Serial1.println("failed to open device");            
			continue; // In case we failed to open this device, continue with next one in the list
            }
            
            const usb_device_desc_t *device_desc;
            ESP_ERROR_CHECK(usb_host_get_device_descriptor(current_device, &device_desc));
			const usb_config_desc_t *config_desc;
			usb_host_get_active_config_descriptor(current_device, &config_desc);
			const usb_standard_desc_t *this_desc = (const usb_standard_desc_t *)config_desc;
			int desc_offset = 0;
			this_desc = usb_parse_next_descriptor(this_desc, config_desc->wTotalLength, &desc_offset);
			
            Serial1.println(device_desc->idVendor); // 0x0403
			Serial1.println(device_desc->idProduct); // 0x6001
			Serial1.println(device_desc->bDeviceClass);
			Serial1.println(device_desc->bDeviceSubClass);
			Serial1.println(device_desc->bDeviceProtocol);
			Serial1.println(device_desc->iSerialNumber);
			Serial1.println(device_desc->bMaxPacketSize0);
			Serial1.println(device_desc->bDescriptorType);
			Serial1.println(device_desc->bNumConfigurations);
			Serial1.println(config_desc->wTotalLength);
			Serial1.println(config_desc->bDescriptorType);
			Serial1.println(config_desc->bNumInterfaces);
			Serial1.println(this_desc->bDescriptorType);
			
			const usb_intf_desc_t* interface_desc = (const usb_intf_desc_t*) this_desc;
			Serial1.println(interface_desc->bInterfaceClass);
			Serial1.println(interface_desc->bInterfaceSubClass);
			Serial1.println(interface_desc->bInterfaceProtocol);

Output:

1027
24577
0
0
0
3
8
1
1
32
2
1
4
255
255
255

The adapter works fine with windows as a serial port. How to make it work with ESP-IDF?

[ESP_Dazz]

Have you tried the CDC Virtual COM Port example?

[dontpostalot]

I haven't and it looks like that's exactly what I need. Thanks!

[Michael.Uray]

Have you tried the CDC Virtual COM Port example?

I am wondering if this virtual COM port example would also work with an ESP32-C6.
It says there that USB OTG is required, which the C6 does not have, but it has UHCI support.
Is there a way to connect an USB-Serial adapter to the ESP32-C6?

[ESP_Sprite]

I am wondering if this virtual COM port example would also work with an ESP32-C6.
It says there that USB OTG is required, which the C6 does not have, but it has UHCI support.
Is there a way to connect an USB-Serial adapter to the ESP32-C6?

No. UHCI in the ESP32 series is an UART function block; it has nothing to do with USB.