Cannot Write Characteristic on BLE onn android app
0
Unable to write characteristic on BLE. The app is capable on connecting to GATT and read characteristics. My first thought is that I am using the wrong UUID's for Tx. Otherwise my characteristic is null for some reason. Here is a screenshot from Nrf Connect
GATT attributes:
public class RBLGattAttributes {
private static HashMap<String, String> attributes = new HashMap<String,
String>();
public static String CLIENT_CHARACTERISTIC_CONFIG = "00002902-0000-1000-
8000-00805f9b34fb";
public static String BLE_SHIELD_TX = "713d0002-503e-4c75-ba94-3148f18d941e";
public static String BLE_SHIELD_RX = "713d0002-503e-4c75-ba94-3148f18d941e";
public static String BLE_SHIELD_SERVICE = "713d0000-503e-4c75-ba94-
3148f18d941e";
static {
// RBL Services.
attributes.put("713d0000-503e-4c75-ba94-3148f18d941e",
"BLE Shield Service");
// RBL Characteristics.
attributes.put(BLE_SHIELD_TX, "BLE Shield TX");
attributes.put(BLE_SHIELD_RX, "BLE Shield RX");
}
public static String lookup(String uuid, String defaultName) {
String name = attributes.get(uuid);
return name == null ? defaultName : name;
}
BLE Service:
public void writeCharacteristic() {
BluetoothGattCharacteristic characteristic=null;
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
if (UUID_BLE_SHIELD_TX.equals(characteristic.getUuid())) {
String ident="I";
byte arr={1};
try {
characteristic.setValue(arr);
} catch (NullPointerException e){Log.w(TAG,"sth is wrong");}
mBluetoothGatt.writeCharacteristic(characteristic);
Error from LogCat:
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.bluetooth.BluetoothGattCharacteristic.getProperties()' on a null object reference
The characteristic is null
android bluetooth-lowenergy uuid gatt edited Nov 24 '18 at 22:09
stkent
13.9k96586
asked Nov 24 '18 at 21:27
Andreas ParlatasAndreas Parlatas
113
add a comment |
0
Unable to write characteristic on BLE. The app is capable on connecting to GATT and read characteristics. My first thought is that I am using the wrong UUID's for Tx. Otherwise my characteristic is null for some reason. Here is a screenshot from Nrf Connect
GATT attributes:
public class RBLGattAttributes {
private static HashMap<String, String> attributes = new HashMap<String,
String>();
public static String CLIENT_CHARACTERISTIC_CONFIG = "00002902-0000-1000-
8000-00805f9b34fb";
public static String BLE_SHIELD_TX = "713d0002-503e-4c75-ba94-3148f18d941e";
public static String BLE_SHIELD_RX = "713d0002-503e-4c75-ba94-3148f18d941e";
public static String BLE_SHIELD_SERVICE = "713d0000-503e-4c75-ba94-
3148f18d941e";
static {
// RBL Services.
attributes.put("713d0000-503e-4c75-ba94-3148f18d941e",
"BLE Shield Service");
// RBL Characteristics.
attributes.put(BLE_SHIELD_TX, "BLE Shield TX");
attributes.put(BLE_SHIELD_RX, "BLE Shield RX");
}
public static String lookup(String uuid, String defaultName) {
String name = attributes.get(uuid);
return name == null ? defaultName : name;
}
BLE Service:
public void writeCharacteristic() {
BluetoothGattCharacteristic characteristic=null;
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
if (UUID_BLE_SHIELD_TX.equals(characteristic.getUuid())) {
String ident="I";
byte arr={1};
try {
characteristic.setValue(arr);
} catch (NullPointerException e){Log.w(TAG,"sth is wrong");}
mBluetoothGatt.writeCharacteristic(characteristic);
Error from LogCat:
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.bluetooth.BluetoothGattCharacteristic.getProperties()' on a null object reference
The characteristic is null
android bluetooth-lowenergy uuid gatt edited Nov 24 '18 at 22:09
stkent
13.9k96586
asked Nov 24 '18 at 21:27
Andreas ParlatasAndreas Parlatas
113
Where ischaracteristicassigned to a non-nullvalue?
– stkent
Nov 24 '18 at 22:09
BluetoothGattCharacteristic characteristic = nullhints for it beingNULL...that's whycharacteristic.getUuid()has no other option, but to fail.
– Martin Zeitler
Nov 24 '18 at 22:14
add a comment |
0
0
0
Unable to write characteristic on BLE. The app is capable on connecting to GATT and read characteristics. My first thought is that I am using the wrong UUID's for Tx. Otherwise my characteristic is null for some reason. Here is a screenshot from Nrf Connect
GATT attributes:
public class RBLGattAttributes {
private static HashMap<String, String> attributes = new HashMap<String,
String>();
public static String CLIENT_CHARACTERISTIC_CONFIG = "00002902-0000-1000-
8000-00805f9b34fb";
public static String BLE_SHIELD_TX = "713d0002-503e-4c75-ba94-3148f18d941e";
public static String BLE_SHIELD_RX = "713d0002-503e-4c75-ba94-3148f18d941e";
public static String BLE_SHIELD_SERVICE = "713d0000-503e-4c75-ba94-
3148f18d941e";
static {
// RBL Services.
attributes.put("713d0000-503e-4c75-ba94-3148f18d941e",
"BLE Shield Service");
// RBL Characteristics.
attributes.put(BLE_SHIELD_TX, "BLE Shield TX");
attributes.put(BLE_SHIELD_RX, "BLE Shield RX");
}
public static String lookup(String uuid, String defaultName) {
String name = attributes.get(uuid);
return name == null ? defaultName : name;
}
BLE Service:
public void writeCharacteristic() {
BluetoothGattCharacteristic characteristic=null;
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
if (UUID_BLE_SHIELD_TX.equals(characteristic.getUuid())) {
String ident="I";
byte arr={1};
try {
characteristic.setValue(arr);
} catch (NullPointerException e){Log.w(TAG,"sth is wrong");}
mBluetoothGatt.writeCharacteristic(characteristic);
Error from LogCat:
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.bluetooth.BluetoothGattCharacteristic.getProperties()' on a null object reference
The characteristic is null
android bluetooth-lowenergy uuid gatt edited Nov 24 '18 at 22:09
stkent
13.9k96586
asked Nov 24 '18 at 21:27
Andreas ParlatasAndreas Parlatas
113
Unable to write characteristic on BLE. The app is capable on connecting to GATT and read characteristics. My first thought is that I am using the wrong UUID's for Tx. Otherwise my characteristic is null for some reason. Here is a screenshot from Nrf Connect
GATT attributes:
public class RBLGattAttributes {
private static HashMap<String, String> attributes = new HashMap<String,
String>();
public static String CLIENT_CHARACTERISTIC_CONFIG = "00002902-0000-1000-
8000-00805f9b34fb";
public static String BLE_SHIELD_TX = "713d0002-503e-4c75-ba94-3148f18d941e";
public static String BLE_SHIELD_RX = "713d0002-503e-4c75-ba94-3148f18d941e";
public static String BLE_SHIELD_SERVICE = "713d0000-503e-4c75-ba94-
3148f18d941e";
static {
// RBL Services.
attributes.put("713d0000-503e-4c75-ba94-3148f18d941e",
"BLE Shield Service");
// RBL Characteristics.
attributes.put(BLE_SHIELD_TX, "BLE Shield TX");
attributes.put(BLE_SHIELD_RX, "BLE Shield RX");
}
public static String lookup(String uuid, String defaultName) {
String name = attributes.get(uuid);
return name == null ? defaultName : name;
}
BLE Service:
public void writeCharacteristic() {
BluetoothGattCharacteristic characteristic=null;
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
if (UUID_BLE_SHIELD_TX.equals(characteristic.getUuid())) {
String ident="I";
byte arr={1};
try {
characteristic.setValue(arr);
} catch (NullPointerException e){Log.w(TAG,"sth is wrong");}
mBluetoothGatt.writeCharacteristic(characteristic);
Error from LogCat:
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.bluetooth.BluetoothGattCharacteristic.getProperties()' on a null object reference
The characteristic is null
android bluetooth-lowenergy uuid gatt android bluetooth-lowenergy uuid gatt edited Nov 24 '18 at 22:09
stkent
13.9k96586
asked Nov 24 '18 at 21:27
Andreas ParlatasAndreas Parlatas
113
edited Nov 24 '18 at 22:09
stkent
13.9k96586
asked Nov 24 '18 at 21:27
Andreas ParlatasAndreas Parlatas
113
edited Nov 24 '18 at 22:09
stkent
13.9k96586
edited Nov 24 '18 at 22:09
stkent
13.9k96586
edited Nov 24 '18 at 22:09
stkent
13.9k96586
13.9k96586
asked Nov 24 '18 at 21:27
Andreas ParlatasAndreas Parlatas
113
asked Nov 24 '18 at 21:27
Andreas ParlatasAndreas Parlatas
113
asked Nov 24 '18 at 21:27
Andreas ParlatasAndreas Parlatas
113
113
Where ischaracteristicassigned to a non-nullvalue?
– stkent
Nov 24 '18 at 22:09
BluetoothGattCharacteristic characteristic = nullhints for it beingNULL...that's whycharacteristic.getUuid()has no other option, but to fail.
– Martin Zeitler
Nov 24 '18 at 22:14
add a comment |
Where ischaracteristicassigned to a non-nullvalue?
– stkent
Nov 24 '18 at 22:09
BluetoothGattCharacteristic characteristic = nullhints for it beingNULL...that's whycharacteristic.getUuid()has no other option, but to fail.
– Martin Zeitler
Nov 24 '18 at 22:14
Where is
characteristic assigned to a non-null value?– stkent
Nov 24 '18 at 22:09
Where is
characteristic assigned to a non-null value?– stkent
Nov 24 '18 at 22:09
BluetoothGattCharacteristic characteristic = null hints for it being NULL ...that's why characteristic.getUuid() has no other option, but to fail.– Martin Zeitler
Nov 24 '18 at 22:14
BluetoothGattCharacteristic characteristic = null hints for it being NULL ...that's why characteristic.getUuid() has no other option, but to fail.– Martin Zeitler
Nov 24 '18 at 22:14
add a comment |
0
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Where is
characteristicassigned to a non-nullvalue?– stkent
Nov 24 '18 at 22:09
BluetoothGattCharacteristic characteristic = nullhints for it beingNULL...that's whycharacteristic.getUuid()has no other option, but to fail.– Martin Zeitler
Nov 24 '18 at 22:14