HELP - const gattServer = await device.gatt()- don't work :/

1. const { createBluetooth } = require('node-ble')
2. const { TEST_DEVICE, TEST_SERVICE, TEST_CHARACTERISTIC, TEST_NOTIFY_SERVICE, TEST_NOTIFY_CHARACTERISTIC } = process.env
3. 
4. async function main () {
5.   const { bluetooth, destroy } = createBluetooth()
6. 
7.   // get bluetooth adapter
8.   const adapter = await bluetooth.defaultAdapter()
9.   await adapter.startDiscovery()
10.   console.log('discovering')
11. 
12.   // get device and connect
13.   const device = await adapter.waitDevice(TEST_DEVICE)
14.   console.log('got device', await device.getAddress(), await device.getName())
15.   await device.connect()
16.   console.log('connected')
17.   // console.log(device)
18.   console.log(await device.getRSSI())
19.   const gattServer = await device.gatt()
20.   console.log(gattServer)
21.   // read write characteristic
22.   const service1 = await gattServer.getPrimaryService("0000180f-0000-1000-8000-00805f9b34fb")
23.   // console.log(service1)
24.   const characteristic1 = await service1.getCharacteristic("00002a19-0000-1000-8000-00805f9b34fb")
25.   // await characteristic1.writeValue(Buffer.from('Hello world'))
26.   const buffer = await characteristic1.readValue()
27.   console.log('read', buffer, buffer.toString())
28. 
29.   destroy()
30. }
31. 
32. main()
33.   .then(console.log)
34.   .catch(console.error)
35. 

---

out:

discovering
got device EC:21:E5:43:94:CA BLESmart_00000044EC21E54394CA
connected
-43

I have trying to connect my blood pressure monitor to extract the data, but in line 19 - (const gattServer = await device.gatt()) doesn’t seem to work. The code stay in line 19 and never get the service in line 22. May some one help me? please!

[rzumbuehl]

@mathbozzi thanks for your reply. I just noticed, that the device immediately gets disconnected after the device.connect() call. That’s the reason in my case why the device.gatt() call does not return. I need to further investigate on this.

[afturner]

@rzumbuehl I was curious if you had discovered why the device was closing the connection immediately. I am observing the same behavior.