diff --git a/src/extensions/scratch3_microbit/index.js b/src/extensions/scratch3_microbit/index.js
index b5775350c..ae131a431 100644
--- a/src/extensions/scratch3_microbit/index.js
+++ b/src/extensions/scratch3_microbit/index.js
@@ -111,20 +111,22 @@ class MicroBit {
 
     /**
      * @param {string} text - the text to display.
+     * @return {Promise} - a Promise that resolves when writing to device.
      */
     displayText (text) {
         const output = new Uint8Array(text.length);
         for (let i = 0; i < text.length; i++) {
             output[i] = text.charCodeAt(i);
         }
-        this._writeSessionData(BLECommand.CMD_DISPLAY_TEXT, output);
+        return this._writeSessionData(BLECommand.CMD_DISPLAY_TEXT, output);
     }
 
     /**
      * @param {Uint8Array} matrix - the matrix to display.
+     * @return {Promise} - a Promise that resolves when writing to device.
      */
     displayMatrix (matrix) {
-        this._writeSessionData(BLECommand.CMD_DISPLAY_LED, matrix);
+        return this._writeSessionData(BLECommand.CMD_DISPLAY_LED, matrix);
     }
 
     /**
@@ -212,6 +214,7 @@ class MicroBit {
      * Write a message to the device BLE session.
      * @param {number} command - the BLE command hex.
      * @param {Uint8Array} message - the message to write.
+     * @return {Promise} - a Promise that resolves when writing to device.
      * @private
      */
     _writeSessionData (command, message) {
@@ -220,8 +223,8 @@ class MicroBit {
         for (let i = 0; i < message.length; i++) {
             output[i + 1] = message[i];
         }
-        const b64enc = Base64Util.uint8ArrayToBase64(output);
-        this._ble.write(BLEUUID.service, BLEUUID.txChar, b64enc, 'base64');
+        const data = Base64Util.uint8ArrayToBase64(output);
+        return this._ble.write(BLEUUID.service, BLEUUID.txChar, data, 'base64');
     }
 }
 
@@ -494,17 +497,18 @@ class Scratch3MicroBitBlocks {
     /**
      * Display text on the 5x5 LED matrix.
      * @param {object} args - the block's arguments.
+     * @return {Promise} - a Promise that resolves when writing to device.
      * Note the limit is 19 characters
      */
     displayText (args) {
         const text = String(args.TEXT).substring(0, 19);
-        this._device.displayText(text);
-        return;
+        return this._device.displayText(text);
     }
 
     /**
      * Display a predefined symbol on the 5x5 LED matrix.
      * @param {object} args - the block's arguments.
+     * @return {Promise} - a Promise that resolves when writing to device.
      */
     displaySymbol (args) {
         const hex = symbols2hex[args.SYMBOL];
@@ -514,8 +518,7 @@ class Scratch3MicroBitBlocks {
         this._device.ledMatrixState[2] = (hex >> 10) & 0x1F;
         this._device.ledMatrixState[3] = (hex >> 5) & 0x1F;
         this._device.ledMatrixState[4] = hex & 0x1F;
-        this._device.displayMatrix(this._device.ledMatrixState);
-        return;
+        return this._device.displayMatrix(this._device.ledMatrixState);
     }
 
     /**
diff --git a/src/io/bleSession.js b/src/io/bleSession.js
index af4f67b92..75eafe7e1 100644
--- a/src/io/bleSession.js
+++ b/src/io/bleSession.js
@@ -18,6 +18,7 @@ class BLESession extends JSONRPCWebSocket {
         this._socketPromise = new Promise((resolve, reject) => {
             this._ws.onopen = resolve;
             this._ws.onerror = this._sendError(); // TODO: socket error?
+            // TODO: generally handle socket disconnects as errors
         });
 
         this._availablePeripherals = {};
@@ -37,18 +38,14 @@ class BLESession extends JSONRPCWebSocket {
     requestDevice () {
         // TODO: add timeout for 'no devices yet found' ?
         if (this._ws.readyState === 1) {
+            // TODO: what if discover doesn't initiate?
             this.sendRemoteRequest('discover', this._deviceOptions)
-                .catch(e => {
-                    // TODO: what if discover doesn't initiate?
-                    this._sendError(e);
-                });
+                .catch(e => this._sendError(e));
         } else {
             // Try again to connect to the websocket
+            // TODO: what if discover doesn't initiate?
             this._socketPromise(this.sendRemoteRequest('discover', this._deviceOptions))
-                .catch(e => {
-                    // TODO: what if discover doesn't initiate?
-                    this._sendError(e);
-                });
+                .catch(e => this._sendError(e));
         }
     }
 
@@ -64,7 +61,7 @@ class BLESession extends JSONRPCWebSocket {
                 this._connectCallback();
             })
             .catch(e => {
-                // TODO: what if the peripheral loses power?
+                // TODO: what if the peripheral loses power? (web socket closes?)
                 // TODO: what if tries to connect to an unknown peripheral id?
                 this._sendError(e);
             });
@@ -77,8 +74,7 @@ class BLESession extends JSONRPCWebSocket {
      * @return {object} - optional return value.
      */
     didReceiveCall (method, params) {
-        // TODO: does didReceiveCall receive any errors?
-        // TODO: Add peripheral 'undiscover' handling
+        // TODO: Add peripheral 'undiscover' handling with timeout?
         switch (method) {
         case 'didDiscoverPeripheral':
             this._availablePeripherals[params.peripheralId] = params;
diff --git a/src/util/jsonrpc-web-socket.js b/src/util/jsonrpc-web-socket.js
index 22310d337..edfdf9373 100644
--- a/src/util/jsonrpc-web-socket.js
+++ b/src/util/jsonrpc-web-socket.js
@@ -27,6 +27,10 @@ class JSONRPCWebSocket extends JSONRPC {
 
     _onSocketMessage (e) {
         const json = JSON.parse(e.data);
+        if (json.method !== 'characteristicDidChange') {
+            console.log('received message: ');
+            console.log(json);
+        }
         this._handleMessage(json);
     }