* \section Module Description\r
* Device Mode USB Class driver framework interface, for the CDC USB Class driver.\r
*\r
+ * \note There are several major drawbacks to the CDC-ACM standard USB class, however\r
+ * it is very standardized and thus usually available as a built-in driver on\r
+ * most platforms, and so is a better choice than a proprietary serial class.\r
+ * \r
+ * One major issue with CDC-ACM is that it requires two Interface descriptors,\r
+ * which will upset most hosts when part of a multi-function "Composite" USB\r
+ * device, as each interface will be loaded into a separate driver instance. To\r
+ * conbat this, you should use the "Interface Association Descriptor" addendum to\r
+ * the USB standard which is available on most OSes when creating Composite devices.\r
+ *\r
+ * Another major oversight is that there is no mechanism for the host to notify the\r
+ * device that there is a data sink on the host side ready to accept data. This\r
+ * means that the device may try to send data while the host isn't listening, causing\r
+ * lengthy blocking timeouts in the transmission routines. To combat this, it is\r
+ * recommended that the virtual serial line DTR (Data Terminal Ready) be used where\r
+ * possible to determine if a host application is ready for data.\r
+ *\r
* @{\r
*/\r
\r
void EVENT_CDC_Device_ControLineStateChanged(USB_ClassInfo_CDC_Device_t* const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1);\r
\r
/** Sends a given string to the attached USB host, if connected. If a host is not connected when the function is called, the\r
- * string is discarded.\r
+ * string is discarded. Bytes will be queued for transmission to the host until either the endpoint bank becomes full, or the\r
+ * \ref CDC_Device_Flush() function is called to flush the pending data to the host. This allows for multiple bytes to be \r
+ * packed into a single endpoint packet, increasing data throughput.\r
+ *\r
+ * \note This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or\r
+ * the call will fail.\r
*\r
* \param[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state\r
* \param[in] Data Pointer to the string to send to the host\r
ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2);\r
\r
/** Sends a given byte to the attached USB host, if connected. If a host is not connected when the function is called, the\r
- * byte is discarded.\r
+ * byte is discarded. Bytes will be queued for transmission to the host until either the endpoint bank becomes full, or the\r
+ * \ref CDC_Device_Flush() function is called to flush the pending data to the host. This allows for multiple bytes to be \r
+ * packed into a single endpoint packet, increasing data throughput.\r
+ *\r
+ * \note This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or\r
+ * the call will fail.\r
*\r
* \param[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state\r
* \param[in] Data Byte of data to send to the host\r
\r
/** Determines the number of bytes received by the CDC interface from the host, waiting to be read.\r
*\r
+ * \note This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or\r
+ * the call will fail.\r
+ *\r
* \param[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state\r
*\r
* \return Total number of buffered bytes received from the host\r
* returns 0. The \ref CDC_Device_BytesReceived() function should be queried before data is received to ensure that no data\r
* underflow occurs.\r
*\r
+ * \note This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or\r
+ * the call will fail.\r
+ *\r
* \param[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state\r
*\r
* \return Next received byte from the host, or 0 if no data received\r
\r
/** Flushes any data waiting to be sent, ensuring that the send buffer is cleared.\r
*\r
+ * \note This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or\r
+ * the call will fail.\r
+ *\r
* \param[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state\r
*\r
* \return A value from the \ref Endpoint_WaitUntilReady_ErrorCodes_t enum\r
* until they are cleared via a second notification. This should be called each time the CDC class driver's \r
* ControlLineStates.DeviceToHost value is updated to push the new states to the USB host.\r
*\r
+ * \note This function must only be called when the Device state machine is in the DEVICE_STATE_Configured state or\r
+ * the call will fail.\r
+ *\r
* \param[in,out] CDCInterfaceInfo Pointer to a structure containing a CDC Class configuration and state\r
*/\r
void CDC_Device_SendControlLineStateChange(USB_ClassInfo_CDC_Device_t* const CDCInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1);\r
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