Support for resistance change

src/server/index.js

@@ -1,4 +1,5 @@
 import {CyclingPowerService} from './services/cycling-power'
+import {FitnessMachineService} from './services/fitness-machine'
 import {BleServer} from '../util/ble-server'
 
 export const DEFAULT_NAME = 'Gymnasticon';
@@ -14,7 +15,8 @@ export class GymnasticonServer extends BleServer {
 	 */
   constructor(bleno, name=DEFAULT_NAME) {
     super(bleno, name, [
-      new CyclingPowerService()
+      new CyclingPowerService(),
+      new FitnessMachineService()
     ])
   }
 

src/server/services/fitness-machine/characteristics/fitness-machine-control-point.js

@@ -0,0 +1,63 @@
+import {Characteristic, Descriptor} from '@abandonware/bleno';
+
+const FLAG_HASCRANKDATA = (1<<5);
+const CRANK_TIMESTAMP_SCALE = 1000 / 1024; // timestamp resolution is 1/1024 sec
+
+/**
+ * Bluetooth LE GATT Cycling Power Measurement Characteristic implementation.
+ */
+export class FitnessMachineControlPoint extends Characteristic {
+  constructor() {
+    super({
+      uuid: '2AD9',
+      properties: ['read', 'write'],
+      descriptors: [
+        new Descriptor({
+          uuid: '2902',
+          value: Buffer.alloc(2)
+        }),
+        new Descriptor({
+          uuid: '2903',
+          value: Buffer.alloc(2)
+        })
+      ]
+    })
+  }
+  onWriteRequest () {
+      console.log('write request', arguments)
+  }
+  onReadRequest (a, callback) {
+    console.log('read request', arguments)
+    callback(Buffer.from([0x80, 1]))
+  }
+
+  /**
+   * Notify subscriber (e.g. Zwift) of new Cycling Power Measurement.
+   * @param {object} measurement - new cycling power measurement.
+   * @param {number} measurement.power - current power (watts)
+	 * @param {object} [measurement.crank] - last crank event.
+   * @param {number} measurement.crank.revolutions - revolution count at last crank event.
+   * @param {number} measurement.crank.timestamp - timestamp at last crank event.
+   */
+//   updateMeasurement({ power, crank }) {
+//     let flags = 0;
+
+//     const value = Buffer.alloc(8);
+//     value.writeInt16LE(power, 2);
+
+//     // include crank data if provided
+//     if (crank) {
+//       const revolutions16bit = crank.revolutions & 0xffff;
+//       const timestamp16bit = Math.floor(crank.timestamp * CRANK_TIMESTAMP_SCALE) & 0xffff;
+//       value.writeUInt16LE(revolutions16bit, 4);
+//       value.writeUInt16LE(timestamp16bit, 6);
+//       flags |= FLAG_HASCRANKDATA;
+//     }
+
+//     value.writeUInt16LE(flags, 0);
+
+//     if (this.updateValueCallback) {
+//       this.updateValueCallback(value)
+//     }
+//   }
+}

src/server/services/fitness-machine/characteristics/fitness-machine-feature.js

@@ -0,0 +1,31 @@
+import {Characteristic, Descriptor} from '@abandonware/bleno';
+
+/**
+ * Bluetooth LE GATT Cycling Power Feature Characteristic implementation.
+ */
+export class FitnessMachineFeatureCharacteristic extends Characteristic {
+  constructor() {
+    super({
+      uuid: '2ACC',
+      properties: ['read'],
+      descriptors: [
+        new Descriptor({
+          uuid: '2901',
+          value: 'Fitness Machine Feature'
+        })
+      ],
+      value: Buffer.from([
+        // Resistance Level Supported
+        1,
+        0,
+        0,
+        0,
+        // Resistance Target Setting Supported
+        32,
+        0,
+        0,
+        0
+      ])
+    })
+  }
+}

src/server/services/fitness-machine/index.js

@@ -0,0 +1,35 @@
+import {PrimaryService} from '@abandonware/bleno';
+import {FitnessMachineFeatureCharacteristic} from './characteristics/fitness-machine-feature';
+import {FitnessMachineControlPoint} from './characteristics/fitness-machine-control-point';
+// import {SensorLocationCharacteristic} from './characteristics/sensor-location';
+
+/**
+ * Bluetooth LE GATT Cycling Power Service implementation.
+ */
+export class FitnessMachineService extends PrimaryService {
+  /**
+   * Create a FitnessMachineService instance.
+   */
+  constructor() {
+    super({
+      uuid: '1818',
+      characteristics: [
+        new FitnessMachineFeatureCharacteristic(),
+        new FitnessMachineControlPoint(),
+        // new SensorLocationCharacteristic(),
+      ]
+    })
+  }
+
+  /**
+   * Notify subscriber (e.g. Zwift) of new Cycling Power Measurement.
+   * @param {object} measurement - new cycling power measurement.
+   * @param {number} measurement.power - current power (watts)
+	 * @param {object} [measurement.crank] - last crank event.
+   * @param {number} measurement.crank.revolutions - revolution count at last crank event.
+   * @param {number} measurement.crank.timestamp - timestamp at last crank event.
+   */
+//   updateMeasurement(measurement) {
+//     this.characteristics[0].updateMeasurement(measurement)
+//   }
+}