In this series of previous articles, we explored the low Bluetooth sensor and learn how to establish a connection. The remaining question is how to get some accurate data from the sensors, but this is not as straightforward as it seems. In this article, we continue to explore the GATT and learn how it is characterized between the host and sensor data exchange. In a previous article, we learned how the sensor device includes a GATT server, and we also released a connection method. GATT server contains one or more of the GATT and services, these GATT services represent different types of data can be exchanged. For example, in SensorTag GATT it contains different services each represent a different sensor assembly (humidity sensors, pressure sensors, etc.) in SensorTag in. Each serving contains a GATT GATT or more features. A GATT feature is a data BLE transmitted through the atomic block. GATT contains a feature of any data and be able to indicate the data type of identity. It also does not contain or contains more GATT description. A GATT description contains metadata about the features, such as 626969-030 Air Jordan 4 Retro Fear Pack Nike Kids Sneakers the characteristic value of the unit, or whether it needs to be notified when the characteristic value changes. Briefly, a GATT server may contain one or more services GATT; GATT Each service may comprise one or more characteristics of GATT; GATT feature Women Nike Air Yeezy II may not contain one or more GATT contain description. In GATT services, features and the description Air Jordan Outlet is one thing in common they are replaced by a Universally Unique Identifier (UUID) to identify. As the name 2015 Nike Free 5.0 suggests UUID, a UUID is a simple unique identifier, which is used to retrieve GATT services, features, or description. For SensorTag write UUID for this can be found in GATT Server Reference documentation. When you first look at the time might be a bit Air Max 2011 Womens Wine Red White Grey confusing, but it is very directly. All 616116-991 Red Black Nike LeBron X PS Elite Online SensorTag UUID have basic values: F0000000 -__ 0451 __- 4000-B000-00000000 where four bold figures are the only become part of GATT to distinguish between different services, features or description. If we look at the 653642-400 Blue Orange Lebron James Mens Basketball Shoes Nike Zoom Soldier VIII 8 humidity sensor, we can see that it's UUID is AA20 (the yellow line at the marked GATT_PRIMARY_SERVICE_UUID). This full-service UUID written F000AA20-0451-4000-B000-00000000. This service has two characteristics: first feature represents the exact sensor data, UUID is AA21, all written for the F000AA21-0451-4000-B000-00000000. 4bytes data representing temperature and humidity: Temperature LSB: Least Significant Bit temperature: Humidity LSB: Humidity most significant bit - we will study how to decode the data later. These characteristics also has a description (GATT_CLIENT_CHAR_CFG_UUID entry), it is not Air Max 2011 Womens Yellow Grey White defined in the document UUID. This is because it is a standard UUID, which function as a public service, so it is very common, which is to change the value registered when we need a notice. Also, we will be more in-depth discussion later. The second feature is a marker, we need to set this flag to open the specific sensor. It's UUID Womens Heels is AA22, all written for the F000AA22-0451-4000-B000-00000000. Likewise, we will at the appropriate time to introduce the how to actually use this tag. To further explain the UUID necessary to say one more thing here, in some cases, especially when they are on SensorTag, they are not equipment. In many sensors may have with common UUID services, and by different manufacturers support structure, these manufacturers have insisted the sensor perform the same function a standard service standards Air Max 2012 Blue Silver White (such as heart rate detector with a standard service definition GATT). Similarly, in the discovery stage to join GATT service UUID is possible, this can provide specific services matching device. Unfortunately SensorTag does not support this feature, so I can not discuss here more content. For those who are interested, can () to complete by calling the different forms of BluetoothAdapter # onStartLeScan. Now that we understand how Authentic Mens Basketball Shoes All Red Nike KD 7 Factory Outlet services are organized, we may begin to directly read the data it? Unfortunately, this is not that simple. Remember GATT server connection consists of two parts: the sensor of GATT server, and a local agent do? New Nike Tr Fit Running Shoes Black We may know that the service does not know the local agents, so we need to guide it to retrieve the list of services on the sensor. This can discoverServices () method to complete: BleService.java private BluetoothGattCallback mGattCallback = new BluetoothGattCallback () {Override public void onConnectionStateChange (BluetoothGatt gatt, int status, int newState) {super.onConnectionStateChange (gatt, status, newState); Log. v (TAG, \u0026 quot; Connection State Changed: \u0026 quot; + (newState Air Jordan 14 Grey Red Womens == BluetoothProfile.STATE_CONNECTED \u0026 quot; Connected \u0026 quot;:? \u0026 quot; Disconnected \u0026 quot;)); if (newState == BluetoothProfile.STATE_CONNECTED) {setState (State.CONNECTED); gatt.discoverServices ();} else {setState (State.IDLE);}}Override public void onServicesDiscovered (BluetoothGatt gatt, int status) {if (status == BluetoothGatt.GATT_SUCCESS) {Log.v (TAG, \u0026 quot; onServicesDiscovered : \u0026 quot; + status);}}} This is an asynchronous method, so we can Nike Air Max boldly call it in the UI thread. We need to define an exact callback method to invoke when the service is completed when found. In the callback method to check the status value it is very important because sometimes it will be called before the service check is completed. Check GATT_SUCCESS value will ensure that we only execute it again when it detects the actual completion of the service. Support service Once loaded into the local broker, we can actually have access to the features it contains, we will continue to discuss Womens Nike Kobe VIII in this series of articles. This article source.Bluetooth low energy (5)