LBLEClient

This class allows users to create connections to remote peripheral devices.

To access device attributes, create LBLEClient object and call LBLEClient::connect to connect to the device in address:

// assume LBLECentral::scan has already performed.
// connect to the 1st device scanned.
LBLEClient client;
LBLEAddress serverAddress = LBLECentral.getBLEAddress(0);
client.connect(serverAddress);
while(!client.connected()){
    delay(100); 
}
// now we are connnected.

Upon successful connection, connected() returns true.

The user can then query if certain GATT services exist on the remote device with getServiceCount(), getServiceUuid() and hasService(uuid).

Once the user confirmed that a service is available, the user may use APIs to read or write characteristics.

There are 2 sets of APIs:

Read or write characteristics based on their UUIDs. This is convenient if you already knew the UUID of the desired characteristics. However, there are many cases that the same UUID may appear on different services on the same BLE device. In these cases, you may end up read or write the characteristics that is not intended.
Read or write characteristics based on service index, and the index of the characteristics in the service, queried by getCharacteristicCount. This set of API allows you to specify a characteristic in a specific service, thus this covers a more general case. However, you need to use getCharacteristicCount and getCharacteristicUuid to ensure the index of the characteristics you want to read or write.

Note that there is no extra "type" checking, so it is up to the user to make sure the value types are matched between read/write APIs and the remote device.

Constructors

LBLEClient

Creates a LBLEClient instance that can be used to connect to peripheral devices.

Syntax

Parameters

none

Returns

LBLEClient instance

Connection Methods

connect()

connected()

disconnect()

Start connecting to a remote peripheral device.

You can use LBLECentral singleton object to scan nearby devices and get their addresses.

Call connected() to check if the connection has been successfully established.

Note: this function also implicitly enumerates all the services and characteristics on the remote device, so it may take a while for this function to return.

Syntax

Parameters

none

Returns

true if the connection attempt starts successfully. Note that this does not mean the connection has been established.

false if fail to start connection.

Service Methods

hasService()

getServiceCount()

getServiceName()

getServiceUuid()

getCharacteristicCount()

Check if a service, identified with an UUID, is available on the remote connected device.

Syntax

Parameters

serviceUUID

128-bit or 16-bit UUID to identify the service.

Returns

true if the service is available on the remote device; false otherwise.

Characteristic Methods

getCharacteristicUuid()

readCharacteristicString()

readCharacteristicInt()

writeCharacteristicFloat()

writeCharacteristicString()

writeCharacteristicInt()

writeCharacteristicFloat()

Get the UUID of a characteristic in the service by its index

Syntax

Parameters

serviceIndex

ranges from 0 to (getServiceCount() - 1).

characteristicIndex

ranges from 0 to (getCharacteristicCount(serviceIndex) - 1).

Returns

Number of characteristics in the service.

Read string value from a characteristic on remote device.

Syntax

Parameters

serviceIndex

ranges from 0 to (getServiceCount() - 1).

characteristicIndex

ranges from 0 to (getCharacteristicCount(serviceIndex) - 1).

Returns

String value of the characteristic. Empty string is returned if fails to read the characteristic.

Read integer value from a characteristic on remote device.

Syntax

Parameters

serviceIndex

ranges from 0 to (getServiceCount() - 1).

characteristicIndex

ranges from 0 to (getCharacteristicCount(serviceIndex) - 1).

Returns

Integral value of the characteristic. 0 is returned if fails to read the characteristic.

Read float value from a characteristic on remote device.

Syntax

Parameters

serviceIndex

ranges from 0 to (getServiceCount() - 1).

characteristicIndex

ranges from 0 to (getCharacteristicCount(serviceIndex) - 1).

Returns

Float value of the characteristic. 0.0f is returned if fails to read the characteristic.

Hepler API that write a characteristic on the remote device as a string.

Syntax

Parameters

uuid

The UUID of the characteristic to read from.

string_to_write

The string value to write.

serviceIndex

ranges from 0 to (getServiceCount() - 1).

characteristicIndex

ranges from 0 to (getCharacteristicCount(serviceIndex) - 1).

Returns

>0 if written successfully.

0 if failed to write.

Hepler API that write a characteristic on the remote device as an integer.

Syntax

Parameters

uuid

The UUID of the characteristic to read from.

int_value

The int value to write.

serviceIndex

ranges from 0 to (getServiceCount() - 1).

characteristicIndex

ranges from 0 to (getCharacteristicCount(serviceIndex) - 1).

Returns

>0 if written successfully.

0 if failed to write.

Hepler API that write a characteristic on the remote device as a float.

Syntax

Parameters

uuid

The UUID of the characteristic to read from.

float_value

The float value to write.

serviceIndex

ranges from 0 to (getServiceCount() - 1).

characteristicIndex

ranges from 0 to (getCharacteristicCount(serviceIndex) - 1).

Returns

>0 if written successfully.

0 if failed to write.

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Last updated 3 years ago

// assume LBLECentral::scan has already performed. // connect to the 1st device scanned. LBLEClient client; LBLEAddress serverAddress = LBLECentral.getBLEAddress(0); client.connect(serverAddress); while(!client.connected()){ delay(100); } // now we are connnected.