USB CDC device example code for STM32F4 shows "Open Pipes:0 *!*ERROR: No open pipes!"

[rangaec01]

Hi am new to STM32,

I had generated USB device CDC example using STM32CubeMX 5.0.0 for STM32F427II and once i connect my DUT it show enumeration warning with following error, kindly see what i am doing wrong or can someone please share me just USB CDC device bare metal example code

Port1] : USB Serial Device

Is Port User Connectable:     no

Is Port Debug Capable:      no

Companion Port Number:      0

Companion Hub Symbolic Link Name: 

Protocols Supported:

 USB 1.1:             yes

 USB 2.0:             yes

 USB 3.0:             no

    ---===>Device Information<===---

String Descriptor for index 2 not available while device is in low power state.

ConnectionStatus:          

Current Config Value:       0x00 -> Device Bus Speed: Full (is not SuperSpeed or higher capable)

Device Address:          0x16

Open Pipes:              0

*!*ERROR: No open pipes!

     ===>Device Descriptor<===

bLength:              0x12

bDescriptorType:          0x01

bcdUSB:             0x0200

bDeviceClass:           0x02 -> This is a Communication Device

bDeviceSubClass:          0x02

*!*ERROR: bDeviceSubClass of 2 is invalid

bDeviceProtocol:          0x00

bMaxPacketSize0:          0x40 = (64) Bytes

idVendor:            0x0A12 = Cambridge Silicon Radio Ltd.

idProduct:            0x3039

bcdDevice:            0x0200

iManufacturer:           0x01

String Descriptor for index 1 not available while device is in low power state.

iProduct:             0x02

String Descriptor for index 2 not available while device is in low power state.

iSerialNumber:           0x03

String Descriptor for index 3 not available while device is in low power state.

bNumConfigurations:        0x01

    ---===>Full Configuration Descriptor<===---

     ===>Configuration Descriptor<===

bLength:              0x09

bDescriptorType:          0x02

wTotalLength:          0x0043 -> Validated

bNumInterfaces:          0x02

bConfigurationValue:        0x01

iConfiguration:          0x00

bmAttributes:           0xC0 -> Self Powered

MaxPower:             0x32 = 100 mA

     ===>Interface Descriptor<===

bLength:              0x09

bDescriptorType:          0x04

bInterfaceNumber:         0x00

bAlternateSetting:         0x00

bNumEndpoints:           0x01

bInterfaceClass:          0x02 -> This is Communications (CDC Control) USB Device Interface Class

bInterfaceSubClass:        0x02

bInterfaceProtocol:        0x01

iInterface:            0x00

 -> This is a Communications (CDC Control) USB Device Interface Class

     ===>Descriptor Hex Dump<===

bLength:              0x05

bDescriptorType:          0x24

05 24 00 10 01 

 -> This is a Communications (CDC Control) USB Device Interface Class

     ===>Descriptor Hex Dump<===

bLength:              0x05

bDescriptorType:          0x24

05 24 01 00 01 

 -> This is a Communications (CDC Control) USB Device Interface Class

     ===>Descriptor Hex Dump<===

bLength:              0x04

bDescriptorType:          0x24

04 24 02 02 

 -> This is a Communications (CDC Control) USB Device Interface Class

     ===>Descriptor Hex Dump<===

bLength:              0x05

bDescriptorType:          0x24

05 24 06 00 01 

     ===>Endpoint Descriptor<===

bLength:              0x07

bDescriptorType:          0x05

bEndpointAddress:         0x82 -> Direction: IN - EndpointID: 2

bmAttributes:           0x03 -> Interrupt Transfer Type

wMaxPacketSize:         0x0008 = 0x08 bytes

bInterval:             0x10

     ===>Interface Descriptor<===

bLength:              0x09

bDescriptorType:          0x04

bInterfaceNumber:         0x01

bAlternateSetting:         0x00

bNumEndpoints:           0x02

bInterfaceClass:          0x0A -> This is a CDC Data USB Device Interface Class

bInterfaceSubClass:        0x00

bInterfaceProtocol:        0x00

iInterface:            0x00

     ===>Endpoint Descriptor<===

bLength:              0x07

bDescriptorType:          0x05

bEndpointAddress:         0x01 -> Direction: OUT - EndpointID: 1

bmAttributes:           0x02 -> Bulk Transfer Type

wMaxPacketSize:         0x0040 = 0x40 bytes

bInterval:             0x00

     ===>Endpoint Descriptor<===

bLength:              0x07

bDescriptorType:          0x05

bEndpointAddress:         0x81 -> Direction: IN - EndpointID: 1

bmAttributes:           0x02 -> Bulk Transfer Type

wMaxPacketSize:         0x0040 = 0x40 bytes

bInterval:             0x00

[rangaec01]

Hi have generated code for CDC class virtual com, how does HID wil come in to picture (sorry my understating is wrong ) Could you please generate bare metal code for CDC class and send me if you wroking one or if you can generate for stm32f427II is my part number.

[Imen.D]

Hello @rangaec01​ ,

Sorry, I comment on your discussion by miskake. I delete my answer as it is not apprpriate for your discussion.

For your case, I recommend you to take as reference the CDC example within STM32CubeF4 firmware package: STM32Cube_FW_F4_V1.23.0\Projects\STM324x9I_EVAL\Applications\USB_Device\CDC_Standalone

You can get inspired from this working CDC Standalone application and modify it depending on your needs.

Kind Regards,

Imen