CDC Class Device Mode Driver
[CDC-ACM (Virtual Serial) Class Driver - LUFA/Drivers/Class/CDC.h]

Data Structures

struct  USB_ClassInfo_CDC_Device_t
 CDC Class Device Mode Configuration and State Structure. More...

Functions

bool CDC_Device_ConfigureEndpoints (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
void CDC_Device_ProcessControlRequest (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
void CDC_Device_USBTask (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
void EVENT_CDC_Device_LineEncodingChanged (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
void EVENT_CDC_Device_ControLineStateChanged (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
void EVENT_CDC_Device_BreakSent (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo, uint8_t Duration) ATTR_NON_NULL_PTR_ARG(1)
uint8_t CDC_Device_SendString (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo, char *const Data, const uint16_t Length) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2)
uint8_t CDC_Device_SendByte (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo, const uint8_t Data) ATTR_NON_NULL_PTR_ARG(1)
uint16_t CDC_Device_BytesReceived (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
uint8_t CDC_Device_ReceiveByte (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
uint8_t CDC_Device_Flush (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
void CDC_Device_SendControlLineStateChange (USB_ClassInfo_CDC_Device_t *const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
void CDC_Device_CreateStream (USB_ClassInfo_CDC_Device_t *CDCInterfaceInfo, FILE *Stream)
void CDC_Device_CreateBlockingStream (USB_ClassInfo_CDC_Device_t *CDCInterfaceInfo, FILE *Stream)

Detailed Description

Module Source Dependencies

The following files must be built with any user project that uses this module:

Description

Device Mode USB Class driver framework interface, for the CDC USB Class driver.

Note:
There are several major drawbacks to the CDC-ACM standard USB class, however it is very standardized and thus usually available as a built-in driver on most platforms, and so is a better choice than a proprietary serial class.

One major issue with CDC-ACM is that it requires two Interface descriptors, which will upset most hosts when part of a multi-function "Composite" USB device, as each interface will be loaded into a separate driver instance. To conbat this, you should use the "Interface Association Descriptor" addendum to the USB standard which is available on most OSes when creating Composite devices.

Another major oversight is that there is no mechanism for the host to notify the device that there is a data sink on the host side ready to accept data. This means that the device may try to send data while the host isn't listening, causing lengthy blocking timeouts in the transmission routines. To combat this, it is recommended that the virtual serial line DTR (Data Terminal Ready) be used where possible to determine if a host application is ready for data.


Function Documentation

uint16_t CDC_Device_BytesReceived ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

Determines the number of bytes received by the CDC interface from the host, waiting to be read.

Note:
This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or the call will fail.
Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
Returns:
Total number of buffered bytes received from the host
bool CDC_Device_ConfigureEndpoints ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

Configures the endpoints of a given CDC interface, ready for use. This should be linked to the library EVENT_USB_Device_ConfigurationChanged() event so that the endpoints are configured when the configuration containing the given CDC interface is selected.

Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
Returns:
Boolean true if the endpoints were successfully configured, false otherwise
void CDC_Device_CreateBlockingStream ( USB_ClassInfo_CDC_Device_t CDCInterfaceInfo,
FILE *  Stream 
)

Identical to CDC_Device_CreateStream(), except that reads are blocking until the calling stream function terminates the transfer. While blocking, the USB and CDC service tasks are called repeatedly to maintain USB communications.

Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
[in,out] Stream Pointer to a FILE structure where the created stream should be placed
void CDC_Device_CreateStream ( USB_ClassInfo_CDC_Device_t CDCInterfaceInfo,
FILE *  Stream 
)

Creates a standard characer stream for the given CDC Device instance so that it can be used with all the regular functions in the avr-libc <stdio.h> library that accept a FILE stream as a destination (e.g. fprintf). The created stream is bidirectional and can be used for both input and output functions.

Reading data from this stream is non-blocking, i.e. in most instances, complete strings cannot be read in by a single fetch, as the endpoint will not be ready at some point in the transmission, aborting the transfer. However, this may be used when the read data is processed byte-per-bye (via getc()) or when the user application will implement its own line buffering.

Note:
The created stream can be given as stdout if desired to direct the standard output from all <stdio.h> functions to the given CDC interface.
Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
[in,out] Stream Pointer to a FILE structure where the created stream should be placed
uint8_t CDC_Device_Flush ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

Flushes any data waiting to be sent, ensuring that the send buffer is cleared.

Note:
This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or the call will fail.
Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
Returns:
A value from the Endpoint_WaitUntilReady_ErrorCodes_t enum
void CDC_Device_ProcessControlRequest ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

Processes incoming control requests from the host, that are directed to the given CDC class interface. This should be linked to the library EVENT_USB_Device_UnhandledControlRequest() event.

Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
uint8_t CDC_Device_ReceiveByte ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

Reads a byte of data from the host. If no data is waiting to be read of if a USB host is not connected, the function returns 0. The CDC_Device_BytesReceived() function should be queried before data is received to ensure that no data underflow occurs.

Note:
This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or the call will fail.
Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
Returns:
Next received byte from the host, or 0 if no data received
uint8_t CDC_Device_SendByte ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo,
const uint8_t  Data 
)

Sends a given byte to the attached USB host, if connected. If a host is not connected when the function is called, the byte is discarded. Bytes will be queued for transmission to the host until either the endpoint bank becomes full, or the CDC_Device_Flush() function is called to flush the pending data to the host. This allows for multiple bytes to be packed into a single endpoint packet, increasing data throughput.

Note:
This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or the call will fail.
Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
[in] Data Byte of data to send to the host
Returns:
A value from the Endpoint_WaitUntilReady_ErrorCodes_t enum
void CDC_Device_SendControlLineStateChange ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

Sends a Serial Control Line State Change notification to the host. This should be called when the virtual serial control lines (DCD, DSR, etc.) have changed states, or to give BREAK notifications to the host. Line states persist until they are cleared via a second notification. This should be called each time the CDC class driver's ControlLineStates.DeviceToHost value is updated to push the new states to the USB host.

Note:
This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or the call will fail.
Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
uint8_t CDC_Device_SendString ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo,
char *const   Data,
const uint16_t  Length 
)

Sends a given string to the attached USB host, if connected. If a host is not connected when the function is called, the string is discarded. Bytes will be queued for transmission to the host until either the endpoint bank becomes full, or the CDC_Device_Flush() function is called to flush the pending data to the host. This allows for multiple bytes to be packed into a single endpoint packet, increasing data throughput.

Note:
This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or the call will fail.
Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
[in] Data Pointer to the string to send to the host
[in] Length Size in bytes of the string to send to the host
Returns:
A value from the Endpoint_Stream_RW_ErrorCodes_t enum
void CDC_Device_USBTask ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

General management task for a given CDC class interface, required for the correct operation of the interface. This should be called frequently in the main program loop, before the master USB management task USB_USBTask().

Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
void EVENT_CDC_Device_BreakSent ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo,
uint8_t  Duration 
)

CDC class driver event for a send break request sent to the device from the host. This is generally used to seperate data or to indicate a special condition to the receiving device.

Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
[in] Duration Duration of the break that has been sent by the host, in milliseconds
void EVENT_CDC_Device_ControLineStateChanged ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

CDC class driver event for a control line state change on a CDC interface. This event fires each time the host requests a control line state change (containing the virtual serial control line states, such as DTR) and may be hooked in the user program by declaring a handler function with the same name and parameters listed here. The new control line states are available in the ControlLineStates.HostToDevice value inside the CDC interface structure passed as a parameter, set as a mask of CDC_CONTROL_LINE_OUT_* masks.

Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
void EVENT_CDC_Device_LineEncodingChanged ( USB_ClassInfo_CDC_Device_t *const   CDCInterfaceInfo  ) 

CDC class driver event for a line encoding change on a CDC interface. This event fires each time the host requests a line encoding change (containing the serial parity, baud and other configuration information) and may be hooked in the user program by declaring a handler function with the same name and parameters listed here. The new line encoding settings are available in the LineEncoding structure inside the CDC interface structure passed as a parameter.

Parameters:
[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state
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