React Native - Is there a way to use bluetooth in peripheral mode? - react-native

Question

I am developing an app in ReactNative offline.
One of the functionalities is to use bluetooth to synchronize the data (that the app was collecting) with other devices that use the same app.
I started to develop this task with the react-native-ble-manager library, i can connect from device A to device B, but I don't understand how to listen to the incoming connection in device B. I need to know this to show a certain view.
can anybody help me?
I am using the correct library?
Thanks!

Answer 1

You can't use only the react-native-ble-manager for this project. The library states in its readme that it is based on cordova-plugin-ble-central, which can only act as a central. For a BLE connection you need a central and a peripheral.
Take a look at react-native-peripheral. It allows you to act as a perihperal, create a characteristic with some data, add it to a service and register it so other devices can find it. This is their usage example:
import Peripheral, { Service, Characteristic } from 'react-native-peripheral'
Peripheral.onStateChanged(state => {
// wait until Bluetooth is ready
if (state === 'poweredOn') {
// first, define a characteristic with a value
const ch = new Characteristic({
uuid: '...',
value: '...', // Base64-encoded string
properties: ['read', 'write'],
permissions: ['readable', 'writeable'],
})
// add the characteristic to a service
const service = new Service({
uuid: '...',
characteristics: [ch],
})
// register GATT services that your device provides
Peripheral.addService(service).then(() => {
// start advertising to make your device discoverable
Peripheral.startAdvertising({
name: 'My BLE device',
serviceUuids: ['...'],
})
})
}
})
There is a section about dynamic values where they explain how you can use the onReadRequest and onWriteRequest callbacks to listen to read and write operations on the peripheral and even return dynamic values on each read request:
new Characteristic({
uuid: '...',
properties: ['read', 'write'],
permissions: ['readable', 'writeable'],
onReadRequest: async (offset?: number) => {
const value = '...' // calculate the value
return value // you can also return a promise
},
onWriteRequest: async (value: string, offset?: number) => {
// store or do something with the value
this.value = value
},
})