USB DUAL CDC endpoints for transferring data - usb

Question

I have emulated two VCPs with only one USB Device. I can send data in one VCP that has the following Endpoint Address.
#define CDC_IN_EP 0x81 /* EP1 for data IN */
#define CDC_OUT_EP 0x01 /* EP1 for data OUT */
#define CDC_CMD_EP 0x82 /* EP2 for CDC commands */
I would like to know if it's possible to send data in the other VCP with other Endpoint Address like:
#define CDC_IN_EP3 0x83 /* EP3 for data IN */
#define CDC_OUT_EP3 0x03 /* EP3 for data OUT */
#define CDC_CMD_EP4 0x84 /* EP4 for CDC commands */
My problem is that addresses others than 0x81 don't allow me to send data over the second VCP. I'm using two CDC interfaces Full-Speed. Normally we can use seven endpoints with CDC_FS and that's what I'm trying to do... I have six Endpoints: three for each VCP and the seventh is Endpoint 0 for configuration.
Have I missed something in the Endpoints Configuration or in the Composite Device Descriptors?
/* USB CDC device Configuration Descriptor */
__ALIGN_BEGIN uint8_t USBD_CDC_CfgFSDesc[USB_CDC_CONFIG_DESC_SIZ] __ALIGN_END =
{
/* Configuration Descriptor */
0x09, /* bLength: Configuration Descriptor size */
USB_DESC_TYPE_CONFIGURATION, /* bDescriptorType: Configuration */
USB_CDC_CONFIG_DESC_SIZ, /* wTotalLength:no of returned bytes */
0x00,
0x04, /* bNumInterfaces: 4 interface */
0x01, /* bConfigurationValue: Configuration value */
0x00, /* iConfiguration: Index of string descriptor describing the configuration */
0xC0, /* bmAttributes: Self powered */
0x32, /* MaxPower 100 mA */
/*---------------------------------------------------------------------------*/
// IAD0
0x08, // bLength: Interface Descriptor size
0x0B, // bDescriptorType: IAD
0x00, // bFirstInterface
0x02, // bInterfaceCount
0x02, // bFunctionClass: CDC
0x02, // bFunctionSubClass
0x01, // bFunctionProtocol
0x02, // iFunction
/* Interface0 Descriptor */
0x09, /* bLength: Interface Descriptor size */
USB_DESC_TYPE_INTERFACE, /* bDescriptorType: Interface */
/* Interface descriptor type */
0x00, /* bInterfaceNumber: Number of Interface */
0x00, /* bAlternateSetting: Alternate setting */
0x01, /* bNumEndpoints: One endpoints used */
0x02, /* bInterfaceClass: Communication Interface Class */
0x02, /* bInterfaceSubClass: Abstract Control Model */
0x01, /* bInterfaceProtocol: Common AT commands */
0x00, /* iInterface: */
/* Header Functional Descriptor */
0x05, /* bLength: Endpoint Descriptor size */
0x24, /* bDescriptorType: CS_INTERFACE */
0x00, /* bDescriptorSubtype: Header Func Desc */
0x10, /* bcdCDC: spec release number */
0x01,
/* Call Management Functional Descriptor */
0x05, /* bFunctionLength */
0x24, /* bDescriptorType: CS_INTERFACE */
0x01, /* bDescriptorSubtype: Call Management Func Desc */
0x03, /* bmCapabilities: D0+D1 */
0x01, /* bDataInterface: 1 */
/* ACM Functional Descriptor */
0x04, /* bFunctionLength */
0x24, /* bDescriptorType: CS_INTERFACE */
0x02, /* bDescriptorSubtype: Abstract Control Management desc */
0x02, /* bmCapabilities */
/* Union Functional Descriptor */
0x05, /* bFunctionLength */
0x24, /* bDescriptorType: CS_INTERFACE */
0x06, /* bDescriptorSubtype: Union func desc */
0x00, /* bMasterInterface: Communication class interface */
0x01, /* bSlaveInterface0: Data Class Interface */
/* Endpoint 2 Descriptor */
0x07, /* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_ENDPOINT, /* bDescriptorType: Endpoint */
CDC_CMD_EP, /* bEndpointAddress */
0x03, /* bmAttributes: Interrupt */
LOBYTE(CDC_CMD_PACKET_SIZE), /* wMaxPacketSize: */
HIBYTE(CDC_CMD_PACKET_SIZE),
0xFF, /* bInterval: */
/*---------------------------------------------------------------------------*/
/*Data class interface descriptor*/
0x09, /* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_INTERFACE, /* bDescriptorType: */
0x01, /* bInterfaceNumber: Number of Interface */
0x00, /* bAlternateSetting: Alternate setting */
0x02, /* bNumEndpoints: Two endpoints used */
0x0A, /* bInterfaceClass: CDC */
0x00, /* bInterfaceSubClass: */
0x00, /* bInterfaceProtocol: */
0x00, /* iInterface: */
/*Endpoint OUT Descriptor*/
0x07, /* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_ENDPOINT, /* bDescriptorType: Endpoint */
CDC_OUT_EP, /* bEndpointAddress */
0x02, /* bmAttributes: Bulk */
LOBYTE(CDC_DATA_FS_MAX_PACKET_SIZE), /* wMaxPacketSize: */
HIBYTE(CDC_DATA_FS_MAX_PACKET_SIZE),
0x00, /* bInterval: ignore for Bulk transfer */
/*Endpoint IN Descriptor*/
0x07, /* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_ENDPOINT, /* bDescriptorType: Endpoint */
CDC_IN_EP, /* bEndpointAddress */
0x02, /* bmAttributes: Bulk */
LOBYTE(CDC_DATA_FS_MAX_PACKET_SIZE), /* wMaxPacketSize: */
HIBYTE(CDC_DATA_FS_MAX_PACKET_SIZE),
0x00, /* bInterval: ignore for Bulk transfer */
/*---------------------------------------------------------------------------*/
// IAD1
0x08, // bLength: Interface Descriptor size
0x0B, // bDescriptorType: IAD
0x02, // bFirstInterface
0x02, // bInterfaceCount
0x02, // bFunctionClass: CDC
0x02, // bFunctionSubClass
0x01, // bFunctionProtocol
0x02, // iFunction
/* Interface1 Descriptor */
0x09, /* bLength: Interface Descriptor size */
USB_DESC_TYPE_INTERFACE, /* bDescriptorType: Interface */
/* Interface descriptor type */
0x02, /* bInterfaceNumber: Number of Interface */
0x00, /* bAlternateSetting: Alternate setting */
0x01, /* bNumEndpoints: One endpoints used */
0x02, /* bInterfaceClass: Communication Interface Class */
0x02, /* bInterfaceSubClass: Abstract Control Model */
0x01, /* bInterfaceProtocol: Common AT commands */
0x00, /* iInterface: */
/*Header Functional Descriptor*/
0x05, /* bLength: Endpoint Descriptor size */
0x24, /* bDescriptorType: CS_INTERFACE */
0x00, /* bDescriptorSubtype: Header Func Desc */
0x10, /* bcdCDC: spec release number */
0x01,
/*Call Management Functional Descriptor*/
0x05, /* bFunctionLength */
0x24, /* bDescriptorType: CS_INTERFACE */
0x01, /* bDescriptorSubtype: Call Management Func Desc */
0x03, /* bmCapabilities: D0+D1 */
0x03, /* bDataInterface: 1 */
/*ACM Functional Descriptor*/
0x04, /* bFunctionLength */
0x24, /* bDescriptorType: CS_INTERFACE */
0x02, /* bDescriptorSubtype: Abstract Control Management desc */
0x02, /* bmCapabilities */
/*Union Functional Descriptor*/
0x05, /* bFunctionLength */
0x24, /* bDescriptorType: CS_INTERFACE */
0x06, /* bDescriptorSubtype: Union func desc */
0x02, /* bMasterInterface: Communication class interface */
0x03, /* bSlaveInterface0: Data Class Interface */
/*Endpoint 2 Descriptor*/
0x07, /* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_ENDPOINT, /* bDescriptorType: Endpoint */
CDC_CMD_EP4, /* bEndpointAddress */
0x03, /* bmAttributes: Interrupt */
LOBYTE(CDC_CMD_PACKET_SIZE), /* wMaxPacketSize: */
HIBYTE(CDC_CMD_PACKET_SIZE),
0xFF, /* bInterval: */
/*---------------------------------------------------------------------------*/
/*Data class interface descriptor*/
0x09, /* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_INTERFACE, /* bDescriptorType: */
0x03, /* bInterfaceNumber: Number of Interface */
0x00, /* bAlternateSetting: Alternate setting */
0x02, /* bNumEndpoints: Two endpoints used */
0x0A, /* bInterfaceClass: CDC */
0x00, /* bInterfaceSubClass: */
0x00, /* bInterfaceProtocol: */
0x00, /* iInterface: */
/*Endpoint OUT Descriptor*/
0x07, /* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_ENDPOINT, /* bDescriptorType: Endpoint */
CDC_OUT_EP3, /* bEndpointAddress */
0x02, /* bmAttributes: Bulk */
LOBYTE(CDC_DATA_FS_MAX_PACKET_SIZE), /* wMaxPacketSize: */
HIBYTE(CDC_DATA_FS_MAX_PACKET_SIZE),
0x00, /* bInterval: ignore for Bulk transfer */
/*Endpoint IN Descriptor*/
0x07, /* bLength: Endpoint Descriptor size */
USB_DESC_TYPE_ENDPOINT, /* bDescriptorType: Endpoint */
CDC_IN_EP3, /* bEndpointAddress */
0x02, /* bmAttributes: Bulk */
LOBYTE(CDC_DATA_FS_MAX_PACKET_SIZE), /* wMaxPacketSize: */
HIBYTE(CDC_DATA_FS_MAX_PACKET_SIZE),
0x00 /* bInterval: ignore for Bulk transfer */
};

Answer 1

I had a similar problem with the STM32 USB device library. When you modify or add a new endpoint address in the configuration descriptor, you also have to set the endpoint address in the PMA (packet memory area). You can do that in the USBD_LL_INIT block with the HAL_PCDEx_PMAConfig function:
USBD_StatusTypeDef USBD_LL_Init (USBD_HandleTypeDef *pdev)
{
/* Init USB_IP */
/* enable USB power on Pwrctrl CR2 register */
HAL_PWREx_EnableVddUSB();
/* Link The driver to the stack */
hpcd_USB_FS.pData = pdev;
pdev->pData = &hpcd_USB_FS;
hpcd_USB_FS.Instance = USB;
hpcd_USB_FS.Init.dev_endpoints = 8;
hpcd_USB_FS.Init.speed = PCD_SPEED_FULL;
hpcd_USB_FS.Init.ep0_mps = DEP0CTL_MPS_8;
hpcd_USB_FS.Init.phy_itface = PCD_PHY_EMBEDDED;
hpcd_USB_FS.Init.Sof_enable = DISABLE;
hpcd_USB_FS.Init.low_power_enable = DISABLE;
hpcd_USB_FS.Init.lpm_enable = DISABLE;
hpcd_USB_FS.Init.battery_charging_enable = DISABLE;
if (HAL_PCD_Init(&hpcd_USB_FS) != HAL_OK)
{
Error_Handler();
}
HAL_PCDEx_PMAConfig((PCD_HandleTypeDef*)pdev->pData , 0x00 , PCD_SNG_BUF, 0x18);
HAL_PCDEx_PMAConfig((PCD_HandleTypeDef*)pdev->pData , 0x80 , PCD_SNG_BUF, 0x58);
HAL_PCDEx_PMAConfig((PCD_HandleTypeDef*)pdev->pData , 0x81 , PCD_SNG_BUF, 0xC0);
HAL_PCDEx_PMAConfig((PCD_HandleTypeDef*)pdev->pData , 0x01 , PCD_SNG_BUF, 0x110);
HAL_PCDEx_PMAConfig((PCD_HandleTypeDef*)pdev->pData , 0x82 , PCD_SNG_BUF, 0x100);
return USBD_OK;
}
After that I could use the new endpoints for data transfer.