Error Status 402 - Not reading characteristic

[a8thunder]

Hi , I connected the Device but not reading the characteristic . AnyBody can help me pls. Thanks you

await peripheral .discoverAllServicesAndCharacteristics() .then((_) => peripheral.services()) .then((services) { log('PRINTING SERVICES for ${peripheral.name}'); return services.first; }).then((service) async { log('PRINTING CHARACTERISTICS FOR SERVICE \n${service.uuid}'); List characteristics = await service.characteristics(); log('PRINTING CHARACTERISTICS FROM \nPERIPHERAL for the same service'); return peripheral.characteristics(service.uuid); }).then((characteristics) { peripheral.requestMtu(185); for (Characteristic characteristic in characteristics) { log('Found characteristic \n ${characteristic.uuid}'); characteristic.isReadable = true; characteristic.isWritableWithResponse = true; characteristic.isWritableWithoutResponse = true; if (characteristic == null) { print("Characteristic not found"); } else { print( "Characteristic:\n" "uuid: ${characteristic.uuid}\n" "isReadable: ${characteristic.isReadable}\n" "isWritableWithoutResponse: ${characteristic.isWritableWithoutResponse}\n" "isWritableWithResponse: ${characteristic.isWritableWithResponse}\n" "isIndicatable: ${characteristic.isIndicatable}\n" "isNotifiable: ${characteristic.isNotifiable}\n", ); } Stream characteristicUpdates = peripheral.monitorCharacteristic( '000018f0-0000-1000-8000-00805f9b34fb', '00002af0-0000-1000-8000-00805f9b34fb'); characteristicUpdates.listen((event) { print('##################'); print('$event'); readCharacteristic(); }, onError: (error) { print('##################'); print('$error'); }).resume(); if (characteristic.uuid.toString().contains(writeCharacteristicUUID)) { Future.delayed(const Duration(milliseconds: 500), () async { // characteristic.is try { print(Uint8List.fromList(utf8.encode('ATZ\n'))); // await characteristic.write( // Uint8List.fromList(utf8.encode('ATZ\n')), false); await peripheral.writeCharacteristic( '000018f0-0000-1000-8000-00805f9b34fb', '00002af1-0000-1000-8000-00805f9b34fb', Uint8List.fromList(utf8.encode('ATZ\n')), false); } catch (e) { print(e.toString()); } }); } } });

this is my console:

flutter: Characteristic{service: Service{peripheralId: F2CCD470-E0F6-2D73-9495-09D446F6DC08, uuid: 000018f0-0000-1000-8000-00805f9b34fb}, _manager: Instance of 'InternalBleManager', uuid: 00002af0-0000-1000-8000-00805f9b34fb, isReadable: false, isWritableWithResponse: false, isWritableWithoutResponse: false, isNotifiable: true, isIndicatable: true} CharacteristicWithValue{value = [65, 84, 90, 10] CharacteristicWithValueAndTransactionId{transactionId: 3} flutter: Reading temperature config flutter: ################## flutter: Characteristic{service: Service{peripheralId: F2CCD470-E0F6-2D73-9495-09D446F6DC08, uuid: 000018f0-0000-1000-8000-00805f9b34fb}, _manager: Instance of 'InternalBleManager', uuid: 00002af0-0000-1000-8000-00805f9b34fb, isReadable: false, isWritableWithResponse: false, isWritableWithoutResponse: false, isNotifiable: true, isIndicatable: true} CharacteristicWithValue{value = [65, 84, 90, 10] CharacteristicWithValueAndTransactionId{transactionId: 4} flutter: Reading temperature config flutter: ################## flutter: BleError (Error code: 402, ATT error code: 2, iOS error code: null, Android error code: null, reason: Reading is not permitted., internal message: null, device ID: F2CCD470-E0F6-2D73-9495-09D446F6DC08, service UUID: 000018f0-0000-1000-8000-00805f9b34fb, characteristic UUID: 00002af0-0000-1000-8000-00805f9b34fb, descriptor UUID: null) flutter: ################## flutter: BleError (Error code: 402, ATT error code: 2, iOS error code: null, Android error code: null, reason: Reading is not permitted., internal message: null, device ID: F2CCD470-E0F6-2D73-9495-09D446F6DC08, service UUID: 000018f0-0000-1000-8000-00805f9b34fb, characteristic UUID: 00002af0-0000-1000-8000-00805f9b34fb, descriptor UUID: null)

[mikolak]

The characteristic you're trying to read does not support reading, only notifications. Use .monitor() and listen to the stream.

[a8thunder]

Hi @mikolak I used monitor and check status characterstic but not read it

uuid: 00002af0-0000-1000-8000-00805f9b34fb isReadable: true isWritableWithoutResponse: false isWritableWithResponse: false isIndicatable: true isNotifiable: true flutter: Characteristic: uuid: 00002af1-0000-1000-8000-00805f9b34fb isReadable: true isWritableWithoutResponse: true isWritableWithResponse: true isIndicatable: false isNotifiable: false [log] Found characteristic 00002af1-0000-1000-8000-00805f9b34fb flutter: [65, 84, 90, 10] flutter: ################## flutter: [65, 84, 90, 10] [log] BleError (Error code: 402, ATT error code: 2, iOS error code: null, Android error code: null, reason: Reading is not permitted., internal message: null, device ID: F2CCD470-E0F6-2D73-9495-09D446F6DC08, service UUID: 000018f0-0000-1000-8000-00805f9b34fb, characteristic UUID: 00002af0-0000-1000-8000-00805f9b34fb, descriptor UUID: null)

for (Characteristic characteristic in characteristics) {
        log('Found characteristic \n ${characteristic.uuid}');
        characteristic.isReadable = true;
        if (characteristic == null) {
          print("Characteristic not found");
        } else {
          print(
            "Characteristic:\n"
            "uuid: ${characteristic.uuid}\n"
            "isReadable: ${characteristic.isReadable}\n"
            "isWritableWithoutResponse: ${characteristic.isWritableWithoutResponse}\n"
            "isWritableWithResponse: ${characteristic.isWritableWithResponse}\n"
            "isIndicatable: ${characteristic.isIndicatable}\n"
            "isNotifiable: ${characteristic.isNotifiable}\n",
          );
        }
        if (characteristic.uuid.toString().contains(nofityCharacteristicUUID)) {
          var monStream = characteristic.monitor();
          monStream.listen((event) {
            print('##################');
            print('$event');
            characteristic.read();
            // readCharacteristic();
          }).onError((error) {
            log(error.toString());
          });
        }
        if (characteristic.uuid.toString().contains(writeCharacteristicUUID)) {
          Future<void>.delayed(const Duration(milliseconds: 500), () async {
            print(Uint8List.fromList(utf8.encode('ATZ\n')));
            // characteristic.is
            try {
              await characteristic.write(
                  Uint8List.fromList(utf8.encode('ATZ\n')), false);
            } catch (e) {
              print(e.toString());
            }
          });
        }
      }

[mikolak]

Whether a characteristic is readable or not is controlled by the peripheral. You cannot change the permission on it, you'd have to change the peripheral's firmware.

In your first log it says that this characteristic is not readable:

flutter: Characteristic{service: Service{peripheralId: F2CCD470-E0F6-2D73-9495-09D446F6DC08, uuid: 000018f0-0000-1000-8000-00805f9b34fb}, _manager: Instance of 'InternalBleManager', uuid: 00002af0-0000-1000-8000-00805f9b34fb, isReadable: false, isWritableWithResponse: false, isWritableWithoutResponse: false, isNotifiable: true, isIndicatable: true}

[a8thunder]

Ok, thank you @mikolak