Update pybricks implementation to newer version

Changes to bluetooth communication according to
https://github.com/pybricks/technical-info/blob/master/pybricks-ble-profile.md#profile-v120

Currently, compatible firmware can be installed from
https://beta.pybricks.com/

Author: Debenben

examples/pybricks_inventorhub.js

@@ -19,14 +19,19 @@ poweredUP.on("discover", async (hub) => { // Wait to discover hubs
         // If the hub transmits something, show it in the console
         hub.on("recieve", (data) => { console.log(data.toString()) });
 
-        hub.stopUserProgram(); // Stop any running user program
-        // The hub is now waiting for a user program to be uploaded which will then get executed
+        // Stop any running user program
+        await hub.stopUserProgram();
 
-        hub.startUserProgram(`
+        // Compiles the python code and uploads it as __main__
+        await hub.uploadUserProgram(`
 from pybricks.hubs import InventorHub
 hub = InventorHub() # We assume the connected hub is an Inventor hub
 hub.display.text("Hello node-poweredup!") # Show on the led matrix of the hub
 print("finished") # Transmit via bluetooth to the laptop
         `);
+
+        // Run the user program that was uploaded on the hub
+        // Alternatively the user program can be started by pressing the button on the hub
+        await hub.startUserProgram();
     }
 });

src/consts.ts

@@ -238,7 +238,8 @@ export enum BLECharacteristic {
     WEDO2_MOTOR_VALUE_WRITE = "00001565-1212-efde-1523-785feabcd123", // "1565"
     WEDO2_NAME_ID = "00001524-1212-efde-1523-785feabcd123", // "1524"
     LPF2_ALL = "00001624-1212-efde-1623-785feabcd123",
-    PYBRICKS_CONTROL = "c5f50002-8280-46da-89f4-6d8051e4aeef",
+    PYBRICKS_COMMAND_EVENT = "c5f50002-8280-46da-89f4-6d8051e4aeef",
+    PYBRICKS_CAPABILITIES = "c5f50003-8280-46da-89f4-6d8051e4aeef",
     PYBRICKS_NUS_RX = "6e400002-b5a3-f393-e0a9-e50e24dcca9e",
     PYBRICKS_NUS_TX = "6e400003-b5a3-f393-e0a9-e50e24dcca9e"
 }

src/hubs/pybrickshub.ts

@@ -8,12 +8,15 @@ const debug = Debug("pybrickshub");
 
 
 /**
- * The PybricksHub is emitted if the discovered device is hub with pybricks firmware.
+ * The PybricksHub is emitted if the discovered device is a hub with Pybricks firmware installed.
+ * To flash your hub with Pybricks firmware, follow the instructions from https://pybricks.com.
+ * The class supports hubs with Pybricks version 3.2.0 or newer.
  * @class PybricksHub
  * @extends BaseHub
  */
 export class PybricksHub extends BaseHub {
-    private _checkSumCallback: ((buffer: Buffer) => any) | undefined;
+    private _maxCharSize: number = 100; // overwritten by value from capabilities characteristic
+    private _maxUserProgramSize: number = 16000; // overwritten by value from capabilities characteristic
 
     public static IsPybricksHub (peripheral: Peripheral) {
         return (
@@ -39,15 +42,20 @@ export class PybricksHub extends BaseHub {
             debug("Connect completed");
             this.emit("connect");
             resolve();
+            this._bleDevice.readFromCharacteristic(Consts.BLECharacteristic.PYBRICKS_CAPABILITIES, (err, data) => {
+              if (data) {
+                this._maxCharSize = data.readUInt16LE(0);
+                this._maxUserProgramSize = data.readUInt32LE(6);
+                debug("Recieved capabilities ", data, " maxCharSize: ", this._maxCharSize, " maxUserProgramSize: ", this._maxUserProgramSize);
+              }
+            });
             this._bleDevice.subscribeToCharacteristic(Consts.BLECharacteristic.PYBRICKS_NUS_TX, this._parseMessage.bind(this));
+            this._bleDevice.subscribeToCharacteristic(Consts.BLECharacteristic.PYBRICKS_COMMAND_EVENT, (data) => debug("Recieved command event ", data));
         });
     }
 
     private _parseMessage (data?: Buffer) {
         debug("Received Message (PYBRICKS_NUS_TX)", data);
-        if(this._checkSumCallback && data) {
-            return this._checkSumCallback(data);
-        }
         this.emit("recieve", data);
     }
 
@@ -56,38 +64,50 @@ export class PybricksHub extends BaseHub {
         return this._bleDevice.writeToCharacteristic(uuid, message);
     }
 
-    public startUserProgram (pythonCode: string) {
+    public uploadUserProgram (pythonCode: string) {
         debug("Compiling Python User Program", pythonCode);
-        return compile("UserProgram.py", pythonCode).then(async (result) => {
+        return compile('userProgram.py', pythonCode).then(async (result) => {
             if(result.mpy) {
-                debug("Uploading Python User Program", result.mpy);
-                const programLength = Buffer.alloc(4);
-                programLength.writeUint32LE(result.mpy.byteLength);
-                const checkSumPromise = new Promise<boolean>((resolve) => {
-                    const checkSum = programLength.reduce((a, b) => a ^ b);
-                    this._checkSumCallback = (data) => resolve(data[0] === checkSum);
-                });
-                this.send(programLength, Consts.BLECharacteristic.PYBRICKS_NUS_RX);
-                await checkSumPromise;
-                const chunkSize = 100;
-                for (let i = 0; i < result.mpy.byteLength; i += chunkSize) {
-                    const chunk = result.mpy.slice(i, i + chunkSize);
-                    const checkSumPromise = new Promise<boolean>((resolve) => {
-                        const checkSum = chunk.reduce((a, b) => a ^ b);
-                        this._checkSumCallback = (data) => resolve(data[0] === checkSum);
-                    });
-                    this.send(Buffer.from(chunk), Consts.BLECharacteristic.PYBRICKS_NUS_RX);
-                    await checkSumPromise;
+                const multiFileBlob = Buffer.concat([Buffer.from([0, 0, 0, 0]), Buffer.from('__main__\0'), result.mpy]);
+                multiFileBlob.writeUInt32LE(result.mpy.length);
+                if(multiFileBlob.length > this._maxUserProgramSize) {
+                  throw new Error(`User program size ${multiFileBlob.length} larger than maximum ${this._maxUserProgramSize}`);
                 }
-                this._checkSumCallback = undefined;
+                debug("Uploading Python User Program", multiFileBlob);
+                await this.writeUserProgramMeta(0);
+                const chunkSize = this._maxCharSize - 5;
+                for (let i = 0; i < multiFileBlob.length; i += chunkSize) {
+                    const chunk = multiFileBlob.slice(i, i + chunkSize);
+                    await this.writeUserRam(i, Buffer.from(chunk));
+                }
+                await this.writeUserProgramMeta(multiFileBlob.length);
                 debug("Finished uploading");
             }
             else throw new Error(`Compiling Python User Program failed: ${result.err}`);
         });
     }
 
     public stopUserProgram () {
-        return this.send(Buffer.from([0]), Consts.BLECharacteristic.PYBRICKS_CONTROL);
+        debug("Stopping Python User Program");
+        return this.send(Buffer.from([0]), Consts.BLECharacteristic.PYBRICKS_COMMAND_EVENT);
+    }
+
+    public startUserProgram () {
+        debug("Starting Python User Program");
+        return this.send(Buffer.from([1]), Consts.BLECharacteristic.PYBRICKS_COMMAND_EVENT);
+    }
+
+    private writeUserProgramMeta (programLength: number) {
+        const message = Buffer.alloc(5);
+        message[0] = 3;
+        message.writeUint32LE(programLength, 1);
+        return this.send(message, Consts.BLECharacteristic.PYBRICKS_COMMAND_EVENT);
+    }
+
+    private writeUserRam (offset: number, payload: Buffer) {
+        const message = Buffer.concat([Buffer.from([4, 0, 0, 0, 0]), payload]);
+        message.writeUint32LE(offset, 1);
+        return this.send(message, Consts.BLECharacteristic.PYBRICKS_COMMAND_EVENT);
     }
 }