Accessory Monitoring API
Changes in Accessory Monitoring API documentation
Changes in Accessory Monitoring API
Purpose
The purpose of this API is to provide information about connected
accessories. It also provides a mechanism to detect accessory connection/disconnection
notifications.
Constraints
Accessory Monitoring API requires S60 5th Edition or later releases.
API description
The Accessory Monitoring API interface offers accessory information
about connected accessories. This API is meant to be used by clients
that need to access information about connected accessories or clients
that need notifications about accessories that connect/disconnect
to the device.The API provides stand-alone implementation units that
are used by the client and the API provides information about the
devices hardware resources.
API class structure
The
CAccessoryMonitor class in Accessory Monitoring
API has functions for getting connected accessory information and
listening the accessory connection notifications. The client must
implement the MAccessoryMonitorObserver class to
receive accessory connection/disconnection notifications. Information
about one accessory is wrapped to instances of class CAccMonitorInfo. Accessory capability definitions for Accessory Monitoring API are
declared in the accmonitorcapabilities.h file.
Related APIs
CAccMonitorInfoCAccessoryMonitorMAccessoryMonitorObserver
Using Accessory Monitoring API
Accessory Monitoring API can be used in:
Accessory information from Accessory Monitoring API is presented
as instances of the
CAccMonitorInfo class. This class
contains accessory capabilities and these capabilities describe the
features of one accessory. Some capabilities can be defined more precisely
by defining values to these capabilities. These values can be asked
from the accessory monitoring API.
Accessory connection/disconnection notifications can be listened
with the
StartListeningL() method. Connection notifications
in client side are received from the MAccMonitorObserver class. The client must implement the pure virtual functions from
this class. Connection notifications are received through the ConnectedL() method and disconnection notifications are
received through the DisconnectedL() method.
Getting accessory information
The client gets connected accessory information.
Getting all connected accessories
The client creates an instance of the
CAccMonitor class and calls the GetConnectedAccessoriesL() method.
This method returns all connected accessories in an array that contains
instances of the CAccMonitorInfo class. Getting accessory's
information from the array is presented in the following code example:
CAccMonitor* accMonitor = CAccMonitor::NewLC();
RConnectedAccessories connectedAccessories;
CleanupClosePushL( connectedAccessories );
accMonitor->GetConnectedAccessoriesL( connectedAccessories );
count = connectedAccessories.Count();
for( TInt i = 0; i != count; i++ )
{
if( connectedAccessories[ i ]->AccDeviceType() == KAccMonHeadset );
{
_LIT( KHeadsetText, "A headset is connected" );
RDebug::Printf( KHeadsetText );
}
}
CleanupStack::PopAndDestroy( &connectedAccessories );
CleanupStack::PopAndDestroy( accMonitor );
Related APIs
CAccMonitorCAccMonitorInfoGetConnectedAccessoriesL()
Getting accessory capabilities
A client gets the capabilities from an instance of
CAccMonitorInfo with methods provided by this class. All the accessories capabilities
are owned by this instance. One capability can be got with method AccCapabilityAtIndex() as is presented in the next example:
// Connected accessories are gotten as in previous example
const TInt lastConnectedAccessory( 0 );
// The accessory that was connected last is first in the array
cAccMonitorInfo* accInfo
= cAccMonitorInfo::NewL( connectedAccessories[ lastConnectedAccessory ] );
for( TInt i = 0; i != accInfo->Count(); i++ )
{
if( accInfo->AccCapabilityAtIndex( i ) == KAccMonStereoAudio )
{
// Some accessory has stereo audio capability
_LIT( StereoText, "Stereo audio can be played to some accessory" );
RDebug::Printf( StereoText );
}
}
delete accInfo;
Related APIs
AccCapabilityAtIndex()CAccMonitorInfo
Getting capability value for an accessory
A client gets a value for a capability. This value for the capability
is gotten from the
CAccMonitor class with the GetCapabilityValueL() method. An example of this is presented
in the next example.
// Connected accessories and their capabilities are got as in previous examples
TAccMonitorCapability capability( KAccMonVideoOut );
TInt value( 0 );
accMonitor->GetCapabilityValueL( accInfo, capability, value );
// Capability value is retuned to value variable
Related APIs
CAccMonitorGetCapabilityValueL()
Listening accessory connection/disconnection notifications
Listening all accessory connection/disconnection notifications
The client starts to listen to all accessory connection/disconnection
notifications with the
StartObservingL( aObserver ) method. Accessory Monitoring API notifies its clients with the ConnectedL() method when an accessory is connected. When
an accessory is disconnected the clients are notified with the DisconnectedL() method.
CAccMonitor* accMonitor = CAccMonitor::NewLC()
TBool isObserving = accMonitor->IsObserving();
if( isObserving )
{
accMonitor->StartObserverL( this );
}
CleanupStack::PopAndDestroy( accMonitor );
Related APIs
Listening accessory type connection/disconnection notifications
The client can start listening specific types of accessory connection/disconnection
notifications with the
StartObservingL( aObserver, aCapabilityArray
) method. The accessory type that needs to be listened can
defined with accessory capabilities. These capabilities are given
as parameter to the function in an array. For example if the client
wants to listen headset connection/disconnection notifications, the
headset capability needs to be appended to an array and this array
is given as parameter to the StartObservingL() function.
Accessory Monitoring API notifies its clients with the Connected method when the listened accessory is connected. When the listened
accessory is disconnected the clients are notified with the Disconnected() method. An example of starting to listen
to headset connection/disconnection notifications:
CAccMonitor* accMonitor = CAccMonitor::NewLC();
RAccMonCapabilityArray capabilityArray;
CleanupClosePushL( capabilityArray );
capabilityArray.Append( KAccMonHeadset );
TBool isObserving = accMonitor->IsObserving();
if( isObserving )
{
accMonitor->StartObserverL( this, capabilityArray );
}
CleanupStack::PopAndDestroy( &capabilityArray );
CleanupStack::PopAndDestroy( accMonitor );
Related APIs
ConnectedDisconnected()StartObservingL()
Listening a specific accessory connection/disconnection notifications
The client starts to listen a specific accessory connection/disconnection
notifications with the
StartObservingL( aObserver, aAccMonitorInfo
) method. An instance of CAccMonitorInfo of the accessory that needs to be listened is given as parameter
to the StartObservingL() method, so this means that
this accessory must have been connected to the terminal to get the
information of this accessory. Accessory Monitoring API notifies its
clients with the ConnectedL() method when the listened
accessory is connected. When the listened accessory is disconnected
the clients are notified with the DisconnectedL()
method. An example of starting to listen to connection/disconnection
notifications from a specific accessory that is connected:
CAccMonitor* accMonitor = CAccMonitor::NewLC();
RConnectedAccessories array;
CleanupClosePushL( array );
accMonitor->GetConnectedAccessoryL( array );
if( isObserving )
{
for( TInt i = 0; count != i; i++ )
{
if( array[ i ]->AccDeviceType() == KAccMonHeadset
&& array[ i ]->AccPhysicalConnection() == KAccMonWired )
{
// Start observing just that wired headset that is connected
accMonitor->StartObserverL( this, array[ i ] );
break;
}
}
}
CleanupStack::PopAndDestroy( &array );
CleanupStack::PopAndDestroy( accMonitor );
Related APIs
CAccMonitorInfoConnectedDisconnectedStartObservingL()
Handling Connected/Disconnected notifications
When Accessory Monitoring API calls the
ConnectedL() method that the client has implemented, the accessory that was listened
is connected to the device. The information about the connected accessory
is delivered in the parameter aAccessoryInfo. The
content of this pointer must be copied to an instance of the CAccMonitorInfo class (with the CopyL() method) because the original pointer is destroyed by Accessory Monitoring
API after this the ConnectedL() method has been run.
void CMyAccMonitorTest::ConnectedL( CAccMonitorInfo* aAccessoryInfo )
{
//Reserve memory for the accessory information instance
iAccessoryInfo = CAccMonitorInfo::NewL();
// Notification about the connected accessory. aAccessoryInfo must
// be copied because the original pointer is deleted after connected method
iAccessoryInfo->CopyL( aAccessoryInfo );
}
Related APIs
CAccMonitorInfoConnectedL()CopyL()aAccessoryInfo
Error handling
When a leave occurs in the active object's
RunL() method the AccMonitorObserverError() method is
called by Accessory Monitoring API. This method must be implemented
by the client. Otherwise standard Symbian error handling
is used.
Related APIs
AccMonitorObserverError()RunL()
Memory overhead
No significant memory overhead. ROM consumption is 4KB.
Extensions to the API
No extensions.
Related APIs
CAccMonitorInfoConnectedL()DisconnectedL()MAccMonitorObserverStartListeningL()
Glossary
Abbreviations
| API |
Application Programming Interface. |
|
OS
|
Operating System
|
Definitions
|
|
|
Accessory
|
A peripheral that is connected to the device.
|
|
Accessory capability
|
A feature or a quality that an accessory has, for example stereo
audio capability means that the accessory has capability for handling
stereo audio.
|
|
Accessory type
|
Accessory that is defined with different features. For example
a mono headset is an accessory that has headset capability and mono
audio capability.
|
|
Capability value
|
A value that the accessory capability can have.
|