added radio dashboard

docs/examples.md

@@ -55,6 +55,11 @@ Here are some fun programs for your @boardname@!
   "description": "easy time tracking",
   "url":"/examples/stop-watch",
   "cardType": "example"
+}, {
+  "name": "Radio Dashboard",
+  "description": "dashboard for radio clients",
+  "url":"/examples/radio-dashboard",
+  "cardType": "example"
 }]
 ```
 

docs/examples/radio-dashboard.md

@@ -0,0 +1,81 @@
+# Radio Dashboard
+
+```typescript
+/**
+ * Radio monitoring dashboard
+ * 
+ * Each radio client is represented by a dot on the screen. 
+ * Once a client is registered, it will stay at the same pixel location
+ * forever.
+ * 
+ * Radio clients can simply send a number (between 0..255) on group 4.
+ * The must transmit the serial number using ``radio.setTransmitSerialNumber(true)``
+ * 
+ * The received number is used to set the LED brightness for that client.
+ * 
+ * If the radio packet is not received for 10sec, the LED starts blinking.
+ */
+
+const lostPing = 10000;
+const group = 4;
+
+interface Client {
+    // client serial id
+    id: number;
+    // sprite on screen
+    sprite: game.LedSprite;
+    // last ping received
+    ping: number;
+}
+
+const clients: Client[] = [];
+
+/* lazy allocate sprite */
+function getClient(id: number): Client {
+    // needs an id to track radio client identity
+    if (!id)
+        return undefined;
+
+    // look for cache clients
+    for (const client of clients)
+        if (client.id == id)
+            return client;
+    const n = clients.length;
+    if (n == 24) // out of pixels 
+        return undefined;
+    const client: Client = {
+        id: id,
+        sprite: game.createSprite(n % 5, n / 5),
+        ping: input.runningTime()
+    }
+    clients.push(client);
+    return client;
+}
+
+// store data received by clients
+radio.onDataPacketReceived(packet => {
+    const client = getClient(packet.serial);
+    if (!client)
+        return;
+
+    client.ping = input.runningTime()
+    client.sprite.setBrightness(packet.receivedNumber & 0xff);
+})
+
+// monitor the sprites and start blinking when no packet is received
+basic.forever(() => {
+    const now = input.runningTime()
+    for (const client of clients) {
+        // lost signal starts blinking
+        if (now - client.ping > lostPing)
+            client.sprite.setBlink(500);
+        else client.sprite.setBlink(0);
+    }
+    basic.pause(500)
+})
+
+// setup the radio and start!
+radio.setGroup(group)
+radio.setTransmitPower(6)
+radio.setTransmitSerialNumber(true)
+```