I wrote an Android Phone app in Android Studio that connects to a UbloX NINA B1 to send and receive data on the SPS Service.
I'm having issues with the incoming data from the NINA B1 (Peripheral). I'm not sure if I connected correctly and turned the notifications on correctly.
Below is the code where I do the connection to the SPS Service. (Hardcoded to select Group 3 and child 0)
@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
// Clicked on a Caracteristic (eg. FIFO or Credits)
public boolean enableNotification() {
// Hardcode for SPS service on NINA B112, can only use this service, other services will not be used
// This groupPosition and childPosition was determined from A_05 code, The selectable list gave these values when selecting SPS service
int groupPosition = 3;
int childPosition = 0;
BluetoothGattCharacteristic characteristic;
characteristic = characteristics_HashMapList.get(services_ArrayList.get(groupPosition).getUuid().toString()).get(childPosition);
// Todo find a better way to do below two lines. This is a temp way to pass characteristic & mBTLE_Service to static variables to use in HomeFragment for sending data
//Copy characteristics of SPS service to static act_characteristic for use by HomeFragment
this.act_characteristic = characteristic;
//Copy mBTLE_Service of SPS service to static act_service for use by HomeFragment
this.act_service = mBTLE_Service;
if (Utils.hasWriteProperty(characteristic.getProperties()) != 0) {
String uuid = characteristic.getUuid().toString();
//act_characteristic.setTitle(uuid);
//act_characteristic.setService(mBTLE_Service);
//act_characteristic.setCharacteristic(characteristic);
//dialog_btle_characteristic.show(getFragmentManager(), "Dialog_BTLE_Characteristic");
} if (Utils.hasReadProperty(characteristic.getProperties()) != 0) {
if (mBTLE_Service != null) {
mBTLE_Service.readCharacteristic(characteristic);
}
} if (Utils.hasNotifyProperty(characteristic.getProperties()) != 0) {
if (mBTLE_Service != null) {
mBTLE_Service.setCharacteristicNotification(characteristic, true);
}
}
return false;
}
Here is where I set the notifications ON, this part I'm not so confident about.
@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
public void setCharacteristicNotification(BluetoothGattCharacteristic characteristic, boolean enabled) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);
BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID.fromString(getString(R.string.CLIENT_CHARACTERISTIC_CONFIG)));
// Todo: if the indications and notifications is to be used, then mode the indications part back into setCharacteristicNotification() and add a check for Indications, then change below code to set both indication and notify
if (enabled) {
// Enable INDICATION & NOTIFICATION
final byte[] ENABLE_INDICATION_NOTIFICATION = {0x03, 0x00};
descriptor.setValue(ENABLE_INDICATION_NOTIFICATION);
}
else {
descriptor.setValue(BluetoothGattDescriptor.DISABLE_NOTIFICATION_VALUE);
}
//ToDo Shorten the delay time so that the Notifications Enable still works
// Delay in milli seconds
int m_sec = 200;
Delay.delay(m_sec, new Delay.DelayCallback() {
@Override
public void afterDelay() {
// Enable Notifications after 200 m_sec Delay
mBluetoothGatt.writeDescriptor(descriptor);
}
});
}
This is where I handle the incoming Bytes, I send a Modbus message from the Phone to NINA B1, then NINA B1 replies with a Modbus message. The Incoming byte count is always < 20 bytes. And I fill the RxBuff until the correct amount of bytes are received AND the Slave Address is correct, then I decode the received message.
@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
private void broadcastUpdate(final String action, final BluetoothGattCharacteristic characteristic) {
final Intent intent = new Intent(action);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
intent.putExtra(EXTRA_UUID, characteristic.getUuid().toString());
}
// For all other profiles, writes the data formatted in HEX.
// Only Pack 20 bytes at a time coming from BLE server into data[]
final byte[] rx_Data;
int tempSlavAdr;
rx_Data = characteristic.getValue();
if (rx_Data != null && rx_Data.length > 0) {
// Only handle message if request came from ReadInput_Thread
if (this.request_flag) {
// ToDO: See if other non Modbus data arrives between packets
// Populate RxBuff
for (int i = 0; i < rx_Data.length; i++) {
this.RxBuff[this.WrPtr++] = rx_Data[i];
}
Log.d(TAG,"QTY Bytes in rx_Data = " + (Integer)rx_Data.length);
// Start Decode message only after all expected bytes are received && first message is Slave Address
// Prevent Negative numbers in Slave Address: tempSlavAdr is used in the the next if statement
tempSlavAdr = (byte) this.RxBuff[0];
if (tempSlavAdr < 0) tempSlavAdr += 256;
if ((this.WrPtr == FragmentHome.ExpectedCount_sent) && (tempSlavAdr == slaveAddr)) {
// Copy RxBuff over to Dec_RxBuff
int Dec_RxBuff[] = new int[255];
for (int i = 0; i < this.WrPtr; i++) {
Dec_RxBuff[i] = (this.RxBuff[i]);
Dec_RxBuff[i] += 256;
Dec_RxBuff[i] = Dec_RxBuff[i] & 0xFF;
}
// Clear flag indicating that Thread Send a Request
this.request_flag = false;
message_rx = false;
// Decode ModbusMessage and message Good
if (modbusHandler.DecodeModbusMessage(Dec_RxBuff)){
message_rx = true;
}
// Decode ModbusMessage and message Bad
else{
message_rx = false;
}
// Clear buffers
WrPtr = 0;
Arrays.fill(rx_Data, (byte) 0);
Arrays.fill(RxBuff, (byte) 0);
// Todo What if WrPtr stop short of Expected counter? Do some protection
// WrPtr > ExpectedCount Clear Buffers
} else if (WrPtr > FragmentHome.ExpectedCount_sent) {
// Clear buffers
// HomeFragment.set_Actual(false);
Log.d(TAG,"RX Count to big expected " + FragmentHome.ExpectedCount_sent + " got " + WrPtr);
WrPtr = 0;
Arrays.fill(rx_Data, (byte) 0);
Arrays.fill(RxBuff, (byte) 0);
}
// Todo Use this intent to pass data to a service to Decode Modbus Data (Service not written yet)
// intent.putExtra(EXTRA_DATA, new String(data) + "\n" + Utils.hexToString(data));
}
}
else {
//intent.putExtra(EXTRA_DATA, "0");
}
//sendBroadcast(intent);
}
I still get some data loss, and not sure how to handle this. Phone and NINA B1 is next to one another so distance is not a problem.
Can I get some help on how to set the indications correctly? And why I might lose bytes.
Marinus
