419 ble server - first time

Author: phoddie

examples/io/ble/server/heartratemonitor-server/main.js

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+/*
+ * Copyright (c) 2025  Moddable Tech, Inc.
+ *
+ *   This file is part of the Moddable SDK.
+ * 
+ *   This work is licensed under the
+ *       Creative Commons Attribution 4.0 International License.
+ *   To view a copy of this license, visit
+ *       <http://creativecommons.org/licenses/by/4.0>.
+ *   or send a letter to Creative Commons, PO Box 1866,
+ *   Mountain View, CA 94042, USA.
+ *
+ */
+
+import { GATTServer} from "embedded:io/bluetoothle/peripheral"
+import Timer from "timer";
+
+const deviceName = "419 HRM";
+
+let hrm = new GATTServer({
+	mtu: 128,
+	services: [
+		// Generic Access Service
+		{
+			uuid: "1800",
+			characteristics: [
+				{
+					uuid: "2a00",	// device name
+					properties: GATTServer.properties.read, 
+					value: ArrayBuffer.fromString(deviceName),
+				},
+				{
+					uuid: "2a01",	// appearance
+					properties: GATTServer.properties.read, 
+					value: Uint8Array.of(0x40, 0x03),
+				},
+			]
+		},
+		// Battery Service
+		{
+			uuid: "180f",
+			characteristics: [
+				{
+					uuid: "2a19",		// // battery level
+					properties: GATTServer.properties.read | GATTServer.properties.write,
+					onRead(connection) {
+						return Uint8Array.of(this.value ?? 50);		// last value written or default of 50%
+					},
+					onWrite(buffer, connection) {			// write support for demonstration purposes
+						this.value = (new Uint8Array(buffer))[0];
+						if (0 === this.value)
+							connection.close();		// out of battery!
+					},
+					descriptors: [
+						{
+							uuid: "2901",		// User description
+							value: ArrayBuffer.fromString("Battery level")
+						},
+						{
+							uuid: "2904",		// Characteristic presentation format
+							value: Uint8Array.of(4, 0, 0xad, 0x27, 1, 0, 0)
+						},
+						{
+							uuid: "2999",		// test
+							onRead() {
+								return Uint8Array.of(this.value ?? 128);
+							},
+							onWrite(buffer) {
+								this.value = (new Uint8Array(buffer))[0];
+							}
+						}
+					]
+				}				
+			]
+		},
+		// Heart Rate Monitor Service
+		{
+			uuid: "180d",
+			characteristics: [
+				{
+					uuid: "2a37",		// heart rate
+					properties: GATTServer.properties.read | GATTServer.properties.indicate,
+					onRead() {
+						return Uint8Array.of(0, 65);	// 65 BPM
+					},
+					onSubscribe(connection) {
+						connection.heartRateTimer ??= Timer.set(() => {
+							connection.notify(this, Uint8Array.of(0, 55 + Math.random() * 10), error => trace(`notify complete ${error}\n`));
+						}, 1, connection.heartRateNotificationInterval * 1000);
+					},
+					onUnsubscribe(connection) {
+						Timer.clear(connection.heartRateTimer);
+						delete connection.heartRateTimer;
+					}
+				}
+			]
+		},
+		// Heart Rate notification frequency – custom service and characteristic
+		{
+			uuid: "cfe6f7f2-16d2-4b7e-9253-a1d1c1577a35",
+			characteristics: [
+				{
+					uuid: "7d3a0f66-19a9-4fc4-b3e6-91a2d2c2e58a",
+					properties: GATTServer.properties.read | GATTServer.properties.write,
+					onRead(connection) {
+						return Uint8Array.of(connection.heartRateNotificationInterval);
+					},
+					onWrite(buffer, connection) {
+						const value = (new Uint8Array(buffer))[0];
+						if (value > 0) {
+							connection.heartRateNotificationInterval = value;
+							if (connection.heartRateTimer)
+								Timer.schedule(connection.heartRateTimer, value * 1000, value * 1000);
+						}
+					},
+					descriptors: [
+						{
+							uuid: "2901",		// User description
+							value: ArrayBuffer.fromString("Update frequency in seconds")
+						}
+					]
+				}
+			]
+		}
+	],
+	onConnect(connection) {
+		trace("connect!\n");
+		connection.heartRateNotificationInterval = 1;
+	},
+	onDisconnect(connection) {
+		trace("disconnect!\n");
+		Timer.clear(connection.heartRateTimer);
+	},
+	onReady(connection) {
+		trace("hrm onReady\n");
+		this.startAdvertising({
+			flags: 6,
+			name: deviceName,
+			manufacturerData: {
+				manufacturer: 1,
+				data: Uint8Array.of(255, 0, 1)
+			},
+			services: ["180d", "180f"],
+			[123]: Uint8Array.of(1,2,3)
+		});
+	},
+	onWarning(msg) {
+		trace(`BLE server warning: ${msg}\n`);
+	}
+});

examples/io/ble/server/heartratemonitor-server/manifest.json

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+{
+	"include": [
+		"$(MODDABLE)/examples/manifest_base.json",
+		"$(MODDABLE)/modules/io/ble/server/manifest.json"
+	],
+	"modules": {
+		"*": "./main"
+	}
+}