@kojibuta/ble-hci-central

ble-hci-central

Bluetooth LE HCI Central for Node.js.

Mostly based on node-bluetooth-hci-socket and noble projects.

NOTE: Currently only supports Linux.

Prerequisites

• On-board Bluetooth 4.0+ controller.

• node-gyp

NOTE: node-gyp is only required if the npm cannot find binary for your OS version.

Install

npm install @kojibuta/ble-hci-central

Usage

import central from "@kojibuta/ble-hci-central";

const onAdvertisement = async (
  type,
  addressType,
  address,
  advLength,
  advData,
  rssi,
  numReports
) => {
  // Wait for an advertisement from target device C1:79:C4:77:5A:06
  if (address !== "c179c4775a06") return;
  central.off("advertisement", onAdvertisement);

  // Stop scanning before opening a connection
  await central.stopScanningAsync();

  // Connect to device
  const connection = await central.connectAsync(addressType, address);
  console.log("connected", connection);

  // Discover all services, characteristics and descriptors
  const services = await central.discoverAsync(address, true);
  console.log("services", JSON.stringify(services, null, 4));

  // Read device name
  const handle = services["1800"]?.characteristics["2a00"]?.handle;
  if (handle) {
    const result = await central.readAsync(address, handle);
    if (result.error) {
      console.log("error reading device name", result.error);
    } else {
      console.log("device name", result.value.toString("utf8"));
    }
  }

  // Close connection
  await central.disconnectAsync(address);

  // That's all folks
  process.exit(0);
};

// Start BLE HCI Central
central.start();

// Register advertisement callback
central.on("advertisement", onAdvertisement);

// Set scan parameters (active scan, allow duplicates)
central.setScanParameters(1, 0x20, 0x20, 0, 0);

// Start scanning
central.startScanning();

Examples

See examples folder for code examples.

Platform Notes

Linux

Install system packages

sudo apt install bluez libbluetooth-dev libcap2-bin cmake

Grant permissions to Node.js

If not running as root, following permissions must be granted to node executable.

sudo setcap 'cap_net_raw,cap_net_admin+eip' $(eval readlink -f `which node`)