@abandonware/noble/examples/pizza/central.js

A Node.js BLE (Bluetooth Low Energy) central library.

/* eslint-disable handle-callback-err */
const noble = require('../..');
const pizza = require('./pizza');

const pizzaServiceUuid = '13333333333333333333333333333337';
const pizzaCrustCharacteristicUuid = '13333333333333333333333333330001';
const pizzaToppingsCharacteristicUuid = '13333333333333333333333333330002';
const pizzaBakeCharacteristicUuid = '13333333333333333333333333330003';

noble.on('stateChange', function (state) {
  if (state === 'poweredOn') {
    //
    // Once the BLE radio has been powered on, it is possible
    // to begin scanning for services. Pass an empty array to
    // scan for all services (uses more time and power).
    //
    console.log('scanning...');
    noble.startScanning([pizzaServiceUuid], false);
  } else {
    noble.stopScanning();
  }
});

let pizzaCrustCharacteristic = null;
let pizzaToppingsCharacteristic = null;
let pizzaBakeCharacteristic = null;

noble.on('discover', function (peripheral) {
  // we found a peripheral, stop scanning
  noble.stopScanning();

  //
  // The advertisment data contains a name, power level (if available),
  // certain advertised service uuids, as well as manufacturer data,
  // which could be formatted as an iBeacon.
  //
  console.log('found peripheral:', peripheral.advertisement);
  //
  // Once the peripheral has been discovered, then connect to it.
  //
  peripheral.connect(function (error) {
    if (error) {
      console.error(error);
    }

    //
    // Once the peripheral has been connected, then discover the
    // services and characteristics of interest.
    //
    peripheral.discoverServices([pizzaServiceUuid], function (error, services) {
      if (error) {
        console.error(error);
        return;
      }

      services.forEach(function (service) {
        //
        // This must be the service we were looking for.
        //
        console.log('found service:', service.uuid);

        //
        // So, discover its characteristics.
        //
        service.discoverCharacteristics([], function (error, characteristics) {
          if (error) {
            console.error(error);
            return;
          }

          characteristics.forEach(function (characteristic) {
            //
            // Loop through each characteristic and match them to the
            // UUIDs that we know about.
            //
            console.log('found characteristic:', characteristic.uuid);

            if (pizzaCrustCharacteristicUuid === characteristic.uuid) {
              pizzaCrustCharacteristic = characteristic;
            } else if (
              pizzaToppingsCharacteristicUuid === characteristic.uuid
            ) {
              pizzaToppingsCharacteristic = characteristic;
            } else if (pizzaBakeCharacteristicUuid === characteristic.uuid) {
              pizzaBakeCharacteristic = characteristic;
            }
          });

          //
          // Check to see if we found all of our characteristics.
          //
          if (
            pizzaCrustCharacteristic &&
            pizzaToppingsCharacteristic &&
            pizzaBakeCharacteristic
          ) {
            //
            // We did, so bake a pizza!
            //
            bakePizza();
          } else {
            console.log('missing characteristics');
          }
        });
      });
    });
  });
});

function bakePizza () {
  //
  // Pick the crust.
  //
  const crust = Buffer.alloc(1);
  crust.writeUInt8(pizza.PizzaCrust.THIN, 0);
  pizzaCrustCharacteristic.write(crust, false, function (err) {
    if (!err) {
      //
      // Pick the toppings.
      //
      const toppings = Buffer.alloc(2);
      toppings.writeUInt16BE(
        pizza.PizzaToppings.EXTRA_CHEESE |
          pizza.PizzaToppings.CANADIAN_BACON |
          pizza.PizzaToppings.PINEAPPLE,
        0
      );
      pizzaToppingsCharacteristic.write(toppings, false, function (err) {
        if (!err) {
          //
          // Subscribe to the bake notification, so we know when
          // our pizza will be ready.
          //
          pizzaBakeCharacteristic.on('read', function (data, isNotification) {
            console.log('Our pizza is ready!');
            if (data.length === 1) {
              const result = data.readUInt8(0);
              console.log('The result is',
                result === pizza.PizzaBakeResult.HALF_BAKED
                  ? 'half baked.'
                  : result === pizza.PizzaBakeResult.BAKED
                    ? 'baked.'
                    : result === pizza.PizzaBakeResult.CRISPY
                      ? 'crispy.'
                      : result === pizza.PizzaBakeResult.BURNT
                        ? 'burnt.'
                        : result === pizza.PizzaBakeResult.ON_FIRE
                          ? 'on fire!'
                          : 'unknown?');
            } else {
              console.log('result length incorrect');
            }
          });
          pizzaBakeCharacteristic.subscribe(function (error) {
            if (error) {
              console.error(error);
              return;
            }

            //
            // Bake at 450 degrees!
            //
            const temperature = Buffer.alloc(2);
            temperature.writeUInt16BE(450, 0);
            pizzaBakeCharacteristic.write(temperature, false, function (err) {
              if (err) {
                console.log('bake error');
              }
            });
          });
        } else {
          console.log('toppings error');
        }
      });
    } else {
      console.log('crust error');
    }
  });
}

process.on('SIGINT', function () {
  console.log('Caught interrupt signal');
  noble.stopScanning(() => process.exit());
});

process.on('SIGQUIT', function () {
  console.log('Caught interrupt signal');
  noble.stopScanning(() => process.exit());
});

process.on('SIGTERM', function () {
  console.log('Caught interrupt signal');
  noble.stopScanning(() => process.exit());
});