A USB Composite Device is a USB Device which uses more than one USB class.
In this use case, the "USB CDC (Composite Device)" module is used to create a USB composite device. Thus, this USB module can be associated with another "Composite Device" module, like "USB HID Mouse (Composite Device)".
Also, you can refer to application note AVR4902 ASF - USB Composite Device.
Setup steps
For the setup code of this use case to work, the basic use case must be followed.
Usage steps
Example code
Content of conf_usb.h:
#define USB_DEVICE_EP_CTRL_SIZE 64
#define USB_DEVICE_NB_INTERFACE (X+2)
#define USB_DEVICE_MAX_EP (X+3)
#define UDI_CDC_DATA_EP_IN_0 (1 | USB_EP_DIR_IN) // TX
#define UDI_CDC_DATA_EP_OUT_0 (2 | USB_EP_DIR_OUT) // RX
#define UDI_CDC_COMM_EP_0 (3 | USB_EP_DIR_IN) // Notify endpoint
#define UDI_CDC_COMM_IFACE_NUMBER_0 X+0
#define UDI_CDC_DATA_IFACE_NUMBER_0 X+1
#define UDI_COMPOSITE_DESC_T \
usb_iad_desc_t udi_cdc_iad; \
udi_cdc_comm_desc_t udi_cdc_comm; \
udi_cdc_data_desc_t udi_cdc_data; \
...
#define UDI_COMPOSITE_DESC_FS \
.udi_cdc_iad = UDI_CDC_IAD_DESC_0, \
.udi_cdc_comm = UDI_CDC_COMM_DESC_0, \
.udi_cdc_data = UDI_CDC_DATA_DESC_0_FS, \
...
#define UDI_COMPOSITE_DESC_HS \
.udi_cdc_iad = UDI_CDC_IAD_DESC_0, \
.udi_cdc_comm = UDI_CDC_COMM_DESC_0, \
.udi_cdc_data = UDI_CDC_DATA_DESC_0_HS, \
...
#define UDI_COMPOSITE_API \
&udi_api_cdc_comm, \
&udi_api_cdc_data, \
...
Workflow
- Ensure that conf_usb.h is available and contains the following parameters required for a USB composite device configuration:
#define USB_DEVICE_EP_CTRL_SIZE 64
#define USB_DEVICE_NB_INTERFACE (X+2)
#define USB_DEVICE_MAX_EP (X+3)
- Ensure that conf_usb.h contains the description of composite device:
#define UDI_CDC_DATA_EP_IN_0 (1 | USB_EP_DIR_IN) // TX
#define UDI_CDC_DATA_EP_OUT_0 (2 | USB_EP_DIR_OUT) // RX
#define UDI_CDC_COMM_EP_0 (3 | USB_EP_DIR_IN) // Notify endpoint
#define UDI_CDC_COMM_IFACE_NUMBER_0 X+0
#define UDI_CDC_DATA_IFACE_NUMBER_0 X+1
- Ensure that conf_usb.h contains the following parameters required for a USB composite device configuration:
#define UDI_COMPOSITE_DESC_T \
...
udi_cdc_comm_desc_t udi_cdc_comm; \
udi_cdc_data_desc_t udi_cdc_data; \
...
#define UDI_COMPOSITE_DESC_FS \
...
...
#define UDI_COMPOSITE_DESC_HS \
...
...
#define UDI_COMPOSITE_API \
...
...
- Note
- The descriptors order given in the four lists above must be the same as the order defined by all interface indexes. The interface index orders are defined through UDI_X_IFACE_NUMBER defines.
Also, the CDC requires a USB Interface Association Descriptor (IAD) for composite device.