Functions
UsbHid.c File Reference

Detailed Description

Contains APIs related to HID (Human Interface Device) device class.

Functions

BYTE USBHID_sendReport (const BYTE *reportData, BYTE intfNum)
BYTE USBHID_receiveReport (BYTE *reportData, BYTE intfNum)
BYTE USBHID_sendData (const BYTE *data, WORD size, BYTE intfNum)
BYTE USBHID_abortSend (WORD *size, BYTE intfNum)
BYTE USBHID_receiveData (BYTE *data, WORD size, BYTE intfNum)
BYTE USBHID_abortReceive (WORD *size, BYTE intfNum)
BYTE USBHID_rejectData (BYTE intfNum)
BYTE USBHID_intfStatus (BYTE intfNum, WORD *bytesSent, WORD *bytesReceived)
BYTE USBHID_bytesInUSBBuffer (BYTE intfNum)

Function Documentation

BYTE USBHID_sendReport ( const BYTE *  reportData,
BYTE  intfNum 
)

Sends a Data Report to the Host.

Parameters:
reportDatais an array containing the report.
intfNumis which HID interface the data should be transmitted over.

Sends a pre-built report reportData to the host, on interface intfNum. The report must be organized to reflect the format defined by the report descriptor in descriptors.c.

When the function returns kUSBHID_sendComplete, the data has been written to the USB transmit buffers, and will be transferred to the host in the next polling frame. If the function returns kUSBHID_busNotAvailable, then the bus has either been disconnected or the device is suspended, allowing no reports to be sent. If the function returns kUSBHID_intfBusyError, it means the USB buffer for the interface has data in it, suggesting that the host has not yet fetched the previously-loaded report.

Returns:
Any of the following:
  • kUSBHID_sendComplete
  • kUSBHID_busNotAvailable
  • kUSBHID_intfBusyError
BYTE USBHID_receiveReport ( BYTE *  reportData,
BYTE  intfNum 
)

Receives a Report from the Host into reportData.

Parameters:
reportDatais an array containing the report.
intfNumis the HID interface over which the data is to be received.

Receives a report from the host into reportData, on interface intfNum. It is expected that the host will organize the report in the format defined by the report descriptor in descriptors.c.

When the function returns kUSBHID_receiveCompleted, the data has been successfully copied from the USB receive buffers into reportData. If the function returns kUSBHID_busNotAvailable, then the bus has either been disconnected or the device is suspended, allowing no reports to be sent. If the function returns kUSBHID_generalError, it means the call failed for unspecified reasons.

The call is intended to be called only when it is known that a report is in the USB buffer. This means it is best called in response to the API calling USBHID_handleDataReceived(), which indicates that a report has been received for interface intfNum.

Returns:
Any of the following:
  • kUSBHID_receiveCompleted
  • kUSBHID_busNotAvailable
  • kUSBHID_intfBusyError
BYTE USBHID_sendData ( const BYTE *  data,
WORD  size,
BYTE  intfNum 
)

Initiates Sending of a User Buffer Over HID Interface.

Parameters:
datais an array of data to be sent.
sizeis the number of bytes to be sent, starting from address data.
intfNumis which data interface the data should be transmitted over.

Initiates sending of a user buffer over HID interface intfNum, of size size and starting at address data. If size is larger than the packet size, the function handles all packetization and buffer management. size has no inherent upper limit (beyond being a 16-bit value).

In most cases where a send operation is successfully started, the function will return kUSBHID_sendStarted. A send operation is said to be underway. At some point, either before or after the function returns, the send operation will complete, barring any events that would preclude it. (Even if the operation completes before the function returns, the return code will still be kUSBHID_sendStarted.)

If the bus is not connected when the function is called, the function returns kUSBHID_busNotAvailable, and no operation is begun. If size is 0, the function returns kUSBHID_generalError. If a previous send operation is already underway for this data interface, the function returns with kUSBHID_intfBusyError.

USB includes low-level mechanisms that ensure valid transmission of data.

See Sec. 7.2 of "Programmer's Guide: MSP430 USB API Stack for CDC/PHDC/HID/MSC" for a detailed discussion of send operations.

Returns:
Any of the following:
  • kUSBHID_sendStarted: a send operation was successfully started.
  • kUSBHID_intfBusyError: a previous send operation is underway.
  • kUSBHID_busNotAvailable: the bus is either suspended or disconnected.
  • kUSBHID_generalError: size was zero, or other errorkUSBHID_receiveCompleted.

Referenced by hidSendDataInBackground(), and hidSendDataWaitTilDone().

BYTE USBHID_abortSend ( WORD *  size,
BYTE  intfNum 
)

Aborts an Active Send Operation on Data Interface.

Parameters:
sizeis the number of bytes that were sent prior to the aboert action.
intfNumis the data interface for which the send should be aborted.

Aborts an active send operation on data interface intfNum. Returns the number of bytes that were sent prior to the abort, in size.

An application may choose to call this function if sending failed, due to factors such as:

  • a surprise removal of the bus
  • a USB suspend event
  • any send operation that extends longer than desired//!
Returns:
kUSB_succeed
BYTE USBHID_receiveData ( BYTE *  data,
WORD  size,
BYTE  intfNum 
)

Receives size Bytes Over HID Interface.

Parameters:
datais an array to contain the data received.
sizeis the number of bytes to be received.
intfNumis which data interface to receive from.

Receives size bytes over HID interface intfNum into memory starting at address data. size has no inherent upper limit (beyond being a 16-bit value).

The function may return with kUSBHID_receiveStarted, indicating that a receive operation is underway. The operation completes when size bytes are received. The application should ensure that the data memory buffer be available during the whole of the receive operation.

The function may also return with kUSBHID_receiveCompleted. This means that the receive operation was complete by the time the function returned.

If the bus is not connected when the function is called, the function returns kUSBHID_busNotAvailable, and no operation is begun. If size is 0, the function returns kUSBHID_generalError. If a previous receive operation is already underway for this data interface, the function returns kUSBHID_intfBusyError.

USB includes low-level mechanisms that ensure valid transmission of data.

See Sec. 7.2 of "Programmer's Guide: MSP430 USB API Stack for CDC/PHDC/HID/MSC" for a detailed discussion of receive operations.

Returns:
Any of the following:
  • kUSBHID_receiveStarted: A receive operation has been successfully started.
  • kUSBHID_receiveCompleted: The receive operation is already completed.
  • kUSBHID_intfBusyError: a previous receive operation is underway.
  • kUSBHID_ busNotAvailable: the bus is either suspended or disconnected.
  • kUSBHID_generalError: size was zero, or other error.

Referenced by hidReceiveDataInBuffer().

BYTE USBHID_abortReceive ( WORD *  size,
BYTE  intfNum 
)

Aborts an Active Recieve Operation on HID Interface.

Parameters:
sizeis the number of bytes that were received and are waiting at the assigned address.
intfNumis the data interface for which the receive should be aborted.

Aborts an active receive operation on HID interface intfNum. Returns the number of bytes that were received and transferred to the data location established for this receive operation. The data moved to the buffer up to that time remains valid.

An application may choose to call this function if it decides it no longer wants to receive data from the USB host. It should be noted that if a continuous stream of data is being received from the host, aborting the operation is akin to pressing a "pause" button; the host will be NAK'ed until another receive operation is opened.

See Sec. 7.2 of "Programmer's Guide: MSP430 USB API Stack for CDC/PHDC/HID/MSC" for a detailed discussion of receive operations.

Returns:
kUSB_succeed
BYTE USBHID_rejectData ( BYTE  intfNum)

Rejects Data Received from the Host.

This function rejects data that has been received from the host, for interface intfNum, that does not have an active receive operation underway. It resides in the USB endpoint buffer and blocks further data until a receive operation is opened, or until rejected. When this function is called, the buffer for this interface is purged, and the data lost. This frees the USB path to resume communication.

See Sec. 7.2 of "Programmer's Guide: MSP430 USB API Stack for CDC/PHDC/HID/MSC" for a detailed discussion of receive operations.

Returns:
kUSB_succeed
BYTE USBHID_intfStatus ( BYTE  intfNum,
WORD *  bytesSent,
WORD *  bytesReceived 
)

Indicates the Status of the HID Interface.

Parameters:
intfNumis the interface number for which the status is being retrieved.
bytesSentIf a send operation is underway, the number of bytes that have been transferred to the host is returned in this location. If no send operation is underway, this returns zero.
bytesReceivedIf a receive operation is underway, the number of bytes that have been transferred to the assigned memory location is returned in this location. If no receive operation is underway, this returns zero.

Indicates the status of the HID interface intfNum. If a send operation is active for this interface, the function also returns the number of bytes that have been transmitted to the host. If a receive operation is active for this interface, the function also returns the number of bytes that have been received from the host and are waiting at the assigned address.

Because multiple flags can be returned, the possible values can be masked together - for example, kUSBHID_waitingForSend + kUSBHID_dataWaiting.

Returns:
Any combination of the following:
  • kUSBHID_waitingForSend: Indicates that a send operation is open on this interface.
  • kUSBHID_waitingForReceive: Indicates that a receive operation is open on this interface.
  • kUSBHID_dataWaiting: Indicates that data has been received from the host for this interface, waiting in the USB receive buffers, lacking an open receive operation to accept it.
  • kUSBHID_busNotAvailable: Indicates that the bus is either suspended or disconnected. Any operations that had previously been underway are now aborted.

Referenced by hidSendDataInBackground(), and hidSendDataWaitTilDone().

BYTE USBHID_bytesInUSBBuffer ( BYTE  intfNum)

Returns the Number of Bytes Waiting in the USB Endpoint Buffer.

Parameters:
intfNumis the data interface whose buffer is to be checked.

Returns the number of bytes waiting in the USB endpoint buffer for intfNum. A non-zero value generally means that no receive operation is open by which these bytes can be copied to a user buffer. If the value is non-zero, the application should either open a receive operation so that the data can be moved out of the endpoint buffer, or the data should be rejected (USBHID_rejectData()).

Returns:
The number of bytes waiting in this buffer.

Referenced by hidReceiveDataInBuffer().


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