MPLAB Harmony USB Stack
|
This function schedules a get current volume control request to the specified channel. Prior to calling this function the user should check if volume control exists on the specified channel by calling the USB_HOST_AUDIO_V1_FeatureUnitChannelVolumeExists function.
If the request was scheduled successfully, the requestHandle parameter will contain a request handle that uniquely identifies this request. If the request could not be scheduled successfully, requestHandle will contain USB_HOST_AUDIO_V1_REQUEST_HANDLE_INVALID.
When the control request completes, the Audio v1.0 Client Driver will call the callback function that was set using the USB_HOST_AUDIO_V1_EntityRequestCallbackSet function. The context parameter specified here will be returned in the callback.
USB_HOST_AUDIO_V1_RESULT USB_HOST_AUDIO_V1_FeatureUnitChannelVolumeGet( USB_HOST_AUDIO_V1_OBJ audioObj, USB_HOST_AUDIO_V1_CONTROL_ENTITY_OBJ entityObject, USB_HOST_AUDIO_V1_REQUEST_HANDLE * requestHandle, uint8_t channelNumber, uint16_t * volume );
Parameters |
Description |
audioObj |
USB Host Audio v1.0 Device object |
entityObject |
Audio control entity object |
requestHandle |
Output parameter that will contain the handle to this request |
channelNumber |
Channel number to which the volume control is addressed |
volume |
Output parameter that will contain the current volume when a request is completed and a callback is received |
None.
MPLAB Harmony USB Stack
|