Pico CDC gets "Function is not supported"

[u77345]

Using the latest development branch, I'm getting "Function is not supported" on a Pico plugged in. The pico runs standard SDK, 1.5.1, the CDC is the vanilla device that is created by pico_enable_stdio_usb.

Is this behavior expected?

This is how the Pico descriptor looks like:

Information for device Pico (VID=0x2E8A PID=0x000A):

------------------------------
Connection Information:
------------------------------
Device current bus speed: FullSpeed
Device supports USB 1.1 specification
Device address: 0x0003
Current configuration value: 0x01
Number of open pipes: 3


------------------------------
Device Descriptor:
------------------------------
0x12	bLength
0x01	bDescriptorType
0x0200	bcdUSB
0xEF	bDeviceClass      (Miscellaneous device)
0x02	bDeviceSubClass   
0x01	bDeviceProtocol   
0x40	bMaxPacketSize0   (64 bytes)
0x2E8A	idVendor
0x000A	idProduct
0x0100	bcdDevice
0x01	iManufacturer   "Raspberry Pi"
0x02	iProduct        "Pico"
0x03	iSerialNumber   "E660C06213865126"
0x01	bNumConfigurations


-------------------------
Configuration Descriptor:
-------------------------
0x09	bLength
0x02	bDescriptorType
0x0054	wTotalLength   (84 bytes)
0x03	bNumInterfaces
0x01	bConfigurationValue
0x00	iConfiguration
0x80	bmAttributes   (Bus-powered Device)
0x7D	bMaxPower      (250 mA)

Interface Association Descriptor:
------------------------------
0x08	bLength
0x0B	bDescriptorType
0x00	bFirstInterface
0x02	bInterfaceCount
0x02	bFunctionClass      (Communication Device Class)
0x02	bFunctionSubClass   (Abstract Control Model - ACM)
0x00	bFunctionProtocol   
0x00	iFunction

Interface Descriptor:
------------------------------
0x09	bLength
0x04	bDescriptorType
0x00	bInterfaceNumber
0x00	bAlternateSetting
0x01	bNumEndPoints
0x02	bInterfaceClass      (Communication Device Class)
0x02	bInterfaceSubClass   (Abstract Control Model - ACM)
0x00	bInterfaceProtocol   
0x04	iInterface   "Board CDC"

CDC Header Functional Descriptor:
------------------------------
0x05	bFunctionalLength
0x24	bDescriptorType
0x00	bDescriptorSubtype
0x0120	bcdCDC

CDC Call Management Functional Descriptor:
------------------------------
0x05	bFunctionalLength
0x24	bDescriptorType
0x01	bDescriptorSubtype
0x00	bmCapabilities
0x01	bDataInterface

CDC Abstract Control Management Functional Descriptor:
------------------------------
0x04	bFunctionalLength
0x24	bDescriptorType
0x02	bDescriptorSubtype
0x02	bmCapabilities

CDC Union Functional Descriptor:
------------------------------
0x05	bFunctionalLength
0x24	bDescriptorType
0x06	bDescriptorSubtype
0x00	bControlInterface
0x01	bSubordinateInterface(0)

Endpoint Descriptor:
------------------------------
0x07	bLength
0x05	bDescriptorType
0x81	bEndpointAddress  (IN endpoint 1)
0x03	bmAttributes      (Transfer: Interrupt / Synch: None / Usage: Data)
0x0008	wMaxPacketSize    (1 x 8 bytes)
0x10	bInterval         (16 frames)

Interface Descriptor:
------------------------------
0x09	bLength
0x04	bDescriptorType
0x01	bInterfaceNumber
0x00	bAlternateSetting
0x02	bNumEndPoints
0x0A	bInterfaceClass      (CDC Data)
0x00	bInterfaceSubClass   
0x00	bInterfaceProtocol   
0x00	iInterface

Endpoint Descriptor:
------------------------------
0x07	bLength
0x05	bDescriptorType
0x02	bEndpointAddress  (OUT endpoint 2)
0x02	bmAttributes      (Transfer: Bulk / Synch: None / Usage: Data)
0x0040	wMaxPacketSize    (64 bytes)
0x00	bInterval         

Endpoint Descriptor:
------------------------------
0x07	bLength
0x05	bDescriptorType
0x82	bEndpointAddress  (IN endpoint 2)
0x02	bmAttributes      (Transfer: Bulk / Synch: None / Usage: Data)
0x0040	wMaxPacketSize    (64 bytes)
0x00	bInterval         

Interface Descriptor:
------------------------------
0x09	bLength
0x04	bDescriptorType
0x02	bInterfaceNumber
0x00	bAlternateSetting
0x00	bNumEndPoints
0xFF	bInterfaceClass      (Vendor specific)
0x00	bInterfaceSubClass   
0x01	bInterfaceProtocol   
0x05	iInterface   "Reset"

Microsoft OS Descriptor is not available. Error code: 0x0000001F


--------------------------------
String Descriptor Table
--------------------------------
Index  LANGID  String
0x00   0x0000  0x0409 
0x01   0x0409  "Raspberry Pi"
0x02   0x0409  "Pico"
0x03   0x0409  "E660C06213865126"
0x04   0x0409  "Board CDC"
0x05   0x0409  "Reset"

------------------------------

Connection path for device: 
Intel(R) 82801FB/FBM USB Universal Host Controller - 2658
Root Hub
Generic USB Hub
Pico (VID=0x2E8A PID=0x000A) Port: 8

Running on: Windows 10 or greater (Build Version 19045)

Brought to you by TDD v2.19.0, Dec  5 2023, 12:08:38

[rsta2]

The message "Function is not supported" belongs to the vendor specific interface descriptor in the last place of the descriptor list, which is ignored by Circle. The 2-2-0 serial CDC interface should work as expected. I tested this successfully with the hello_world/usb sample from the pico-examples project.

[u77345]

Thanks Rene! Pico shows up as "utty1".

[u77345]

However, reads from the device gets garbled bytes. Did not try Write(). This is how I acquire the device:

m_pUSBSerialDevice = (CUSBSerialDevice *)(
		CDeviceNameService::Get ()->GetDevice ("utty1", FALSE));

And this is how I read from it in the main loop:

		if (m_pUSBSerialDevice)
		{
			char Buffer[100];
			int nResult = m_pUSBSerialDevice->Read (Buffer, sizeof Buffer);
			if (nResult > 0)
			{	
				m_Serial.Write (Buffer, nResult);
			}
		}

I'm reading [49 49 8A 49 04 91 A3 23 C4 1A 0A 35 FE] instead of [49 52 51 3A 20 32 37 20 34 0A]

What could possibly be the problem?

[rsta2]

Unfortunately I don't know. With this example, installed on the Pico, and the attached test program, running on a RPi 3B, everything looks all right to me. Perhaps you can try it with these programs?

userial-test.zip

[u77345]

Like always, thanks Rene! Found the bug in my code, the stick parity test code left the m_Serial framing modified, that's why the log output was garbled. Your CDC support is awesome!