Error to enable notifications for notify properties

[renatoramossilva]

Hello,

i am developing a app to get all measurements from a glucose meter and basically the app is reading 3 set of informations Service / Characteristic 1808 / 2a18 1808 / 2a24 180A / All characteristics for this service

For to read the info about the characteristics form the 180a service is easy, because these properties are READ. So, I can get these info using "readCharacteristicForDevice"

In case the service 1808 the characteristics are "NOTIFY", so I need use "monitorCharacteristicForDevice" and write by RACP (0x0101 - for all measurements) and it works for one specific glucose model.

My problem is that for the second one device model I need to enable these characteristics before to read the info. When I try read the info from the second model I received the follow message error:

BleError: Characteristic 00002a52-0000-1000-8000-00805f9b34fb write failed for device 54:6C:0E:A0:7B:6D and service 00001808-0000-1000-8000-00805f9b34fb

My question is, how I can enable these characteristics scs using react-native-ble-plx lib?

I am using this function to do it, but it doesn’t nt work yet.

enable_notify(device) {
    console.log('enable_notify...');
    this
      .discoverAllServicesAndCharacteristicsForDevice(device.id)
      .then(() => {
        this.servicesForDevice(device.id).then(services => {
          this
            .characteristicsForDevice(
              device.id,
              service,
            )
            .then(() => {
              try {
                var myData = '0x0001';

                const dataMostSignificantByte = (myData >> 8) & 0xff;
                const dataLeastSignificantByte = myData & 0xff;

                const dataByteArrayInLittleEndian = [
                  dataLeastSignificantByte,
                  dataMostSignificantByte,
                ];
                const dataInBase64 = Buffer.from(
                  dataByteArrayInLittleEndian,
                ).toString('base64');

                this
                  .writeCharacteristicWithResponseForDevice(
                    device.id,
                    "00001808-0000-1000-8000-00805f9b34fb",
                    "00002a34-0000-1000-8000-00805f9b34fb",
                    dataInBase64,
                  )
              } catch (err) { console.log('Error (write): ' + err); }
            });
        });
      });
  } 

I am writing 0100 because I am using the nrF Logger to understand the message flow and I found it.

D 19:45:31.328 gatt.setCharacteristicNotification(00002a34-0000-1000-8000-00805f9b34fb, true) V 19:45:31.336 Enabling notifications for 00002a34-0000-1000-8000-00805f9b34fb D 19:45:31.344 gatt.writeDescriptor(00002902-0000-1000-8000-00805f9b34fb, value=0x01-00) I 19:45:31.495 Data written to descr. 00002902-0000-1000-8000-00805f9b34fb, value: (0x) 01-00 I 19:45:31.503 Notifications enabled

[dariuszseweryn]

wiki

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[joaovitorqueiroz]

@renatoramossilva Did you manage to take the glucose measurements? I'm having trouble getting the values

[renatoramossilva]

@renatoramossilva Did you manage to take the glucose measurements? I'm having trouble getting the values

Yes! I did! What is your issue?

[yaswanthccbp]

@renatoramossilva we are working on a device by using this we got services and their respective characteristics,among those characteristics we have one characteristic with notify property(isNotifiable:true,isNotifying:false) and a client characteristic configuration descriptor. now we want to make this isNotifying property value to true so that we can get some data stream from the device i refered this document ,in this there is a statement like "to set the notification value, we need to tell the sensor to enables us this notification mode. We will write to the characteristic’s descriptor to set the right value: Notify or Indicate".

in ble-plx there is a method bleManager.writeDescriptorForDevice(), we tried using this but ended up with an error,

so,help me in getting the device data by making isNotifying property value true

[keerthi552]

@renatoramossilva in your code you have used base64 value in writeCharacteristicWithResponseForDevice ,can we give any value or there is a specific base64 value,if it is a specific then how can we get that specific value

[jaimebg]

@renatoramossilva I'm also having problems receiving notifications, isNotifying is always false and I cannot seem to find any doc on how to activate it, monitorCharacteristicForDevice is not responding anything

[diegobonagurio]

@renatoramossilva any position about this problem?

[diegobonagurio]

@renatoramossilva

This worked for me. No need to enable notification.

[abursztynowska]

I'm excited to inform you that we've released a new version of react-native-ble-plx. Many of the concerns and bugs have been addressed in this update.

If you encounter any issues or have further suggestions, please don't hesitate to open a new issue.