Merge pull request #115 from benbrown/fix-serial-heartbeat

Add serial heartbeat to keep alive

src/adapters/serialConnection.ts

@@ -25,6 +25,9 @@ export class SerialConnection extends MeshDevice {
    *  through a transform stream (https://stackoverflow.com/questions/71262432) */
   private pipePromise?: Promise<void>;
 
+  /* Reference for the heartbeat ping interval so it can be canceled on disconnect. */ 
+  private heartbeatInterval?: ReturnType<typeof setInterval> | undefined;
+
   /**
    * Fires when `disconnect()` is called, used to instruct serial port and
    * readers to release there locks
@@ -44,6 +47,7 @@ export class SerialConnection extends MeshDevice {
     this.transformer = undefined;
     this.onReleaseEvent = new SimpleEventDispatcher<boolean>();
     this.preventLock = false;
+    this.heartbeatInterval = undefined;
 
     this.log.debug(
       Types.Emitter[Types.Emitter.Constructor],
@@ -125,6 +129,7 @@ export class SerialConnection extends MeshDevice {
     });
 
     this.preventLock = false;
+
     /** Connect to device */
     await this.port
       .open({
@@ -151,6 +156,14 @@ export class SerialConnection extends MeshDevice {
           this.configure().catch(() => {
             // TODO: FIX, workaround for `wantConfigId` not getting acks.
           });
+
+          // Set up an interval to send a heartbeat ping once every minute.
+          // The firmware requires at least one ping per 15 minutes, so this should be more than enough.
+          this.heartbeatInterval = setInterval(() => {
+            this.heartbeat().catch((err) => {
+              console.error('Heartbeat error', err);
+            });
+          }, 60*1000);
         } else {
           console.log("not readable or writable");
         }
@@ -180,6 +193,12 @@ export class SerialConnection extends MeshDevice {
     if (this.port?.readable) {
       await this.port?.close();
     }
+
+    // stop the interval when disconnecting.
+    if (this.heartbeatInterval) {
+      clearInterval(this.heartbeatInterval);
+      this.heartbeatInterval = undefined;      
+    }
     // -------
     this.updateDeviceStatus(Types.DeviceStatusEnum.DeviceDisconnected);
     this.complete();

src/meshDevice.ts

@@ -735,6 +735,23 @@ export abstract class MeshDevice {
     return this.sendRaw(toBinary(Protobuf.Mesh.ToRadioSchema, toRadio));
   }
 
+  /** Serial connection requires a heartbeat ping to stay connected, otherwise times out after 15 minutes */
+  public heartbeat(): Promise<number> {
+    this.log.debug(
+      Types.Emitter[Types.Emitter.Ping],
+      "❤️ Send heartbeat ping to radio",
+    );
+
+    const toRadio = create(Protobuf.Mesh.ToRadioSchema, {
+      payloadVariant: {
+        case: "heartbeat",
+        value: {},
+      },
+    });
+
+    return this.sendRaw(toBinary(Protobuf.Mesh.ToRadioSchema, toRadio));
+  }
+
   /** Sends a trace route packet to the designated node */
   public async traceRoute(destination: number): Promise<number> {
     const routeDiscovery = create(Protobuf.Mesh.RouteDiscoverySchema, {