diff --git a/dist/secure-dfu.js b/dist/secure-dfu.js
index a397bf7..1a340c0 100644
--- a/dist/secure-dfu.js
+++ b/dist/secure-dfu.js
@@ -46,11 +46,13 @@
     const SERVICE_UUID = 0xFE59;
     const CONTROL_UUID = "8ec90001-f315-4f60-9fb8-838830daea50";
     const PACKET_UUID = "8ec90002-f315-4f60-9fb8-838830daea50";
+    const BUTTON_UUID = "8ec90003-f315-4f60-9fb8-838830daea50";
 
     const LITTLE_ENDIAN = true;
     const PACKET_SIZE = 20;
 
     const OPERATIONS = {
+        BUTTON_COMMAND:         [0x01],
         CREATE_COMMAND:         [0x01, 0x01],
         CREATE_DATA:            [0x01, 0x02],
         RECEIPT_NOTIFICATIONS:  [0x02],
@@ -58,7 +60,7 @@
         EXECUTE:                [0x04],
         SELECT_COMMAND:         [0x06, 0x01],
         SELECT_DATA:            [0x06, 0x02],
-        RESPONSE:               [0x60]
+        RESPONSE:               [0x60, 0x20]
     };
 
     const RESPONSE = {
@@ -95,10 +97,8 @@
         this.crc32 = crc32;
         this.events = {};
         this.notifyFns = {};
-        this.connected = false;
         this.controlChar = null;
         this.packetChar = null;
-        this.buffer = null;
     }
 
     function createListenerFn(eventTypes) {
@@ -129,65 +129,163 @@
         });
     };
 
-    secureDfu.prototype.requestDevice = function(filters) {
-        if (!filters) {
-            filters = [{
-                services: [SERVICE_UUID]
-            }];
+    secureDfu.prototype.progress = function(bytes) {
+        this.dispatchEvent({
+            type: "progress",
+            object: "unknown",
+            totalBytes: 0,
+            currentBytes: bytes
+        });
+    }
+
+    secureDfu.prototype.requestDevice = function(hiddenDfu, filters) {
+        if (!hiddenDfu && !filters) {
+            filters = [{ services: [SERVICE_UUID] }];
         }
 
         return bluetooth.requestDevice({
             filters: filters,
+            acceptAllDevices: !filters,
             optionalServices: [SERVICE_UUID]
+        })
+        .then(device => {
+            if (hiddenDfu) {
+                return this.setDfuMode(device);
+            }
+            return device;
         });
     };
 
-    secureDfu.prototype.connect = function(device) {
-        let service = null;
+    secureDfu.prototype.setDfuMode = function(device) {
+        return this.gattConnect(device)
+        .then(characteristics => {
+            this.log(`found ${characteristics.length} characteristic(s)`);
 
-        device.addEventListener("gattserverdisconnected", event => {
-            this.connected = false;
-            this.controlChar = null;
-            this.packetChar = null;
-            this.buffer = null;
-            this.log("disconnected");
-        });
+            let controlChar = characteristics.find(characteristic => {
+                return (characteristic.uuid === CONTROL_UUID);
+            });
+            let packetChar = characteristics.find(characteristic => {
+                return (characteristic.uuid === PACKET_UUID);
+            });
 
-        return device.gatt.connect()
-        .then(gattServer => {
-            this.log("connected to gatt server");
-            return gattServer.getPrimaryService(SERVICE_UUID);
-        })
-        .then(primaryService => {
-            this.log("found DFU service");
-            service = primaryService;
-            return service.getCharacteristic(CONTROL_UUID);
-        })
-        .then(characteristic => {
-            this.log("found control characteristic");
-            if (!characteristic.properties.notify) {
-                throw new Error("control characterisitc does not allow notifications");
+            if (controlChar && packetChar) {
+                return device;
             }
-            this.controlChar = characteristic;
-            return characteristic.startNotifications();
+
+            let buttonChar = characteristics.find(characteristic => {
+                return (characteristic.uuid === BUTTON_UUID);
+            });
+
+            if (!buttonChar) {
+                throw new Error("Unsupported device");
+            }
+
+            // Support buttonless devices
+            this.log("found buttonless characteristic");
+            if (!buttonChar.properties.notify && !buttonChar.properties.indicate) {
+                throw new Error("Buttonless characteristic does not allow notifications");
+            }
+
+            return buttonChar.startNotifications()
+            .then(() => {
+                this.log("enabled buttonless notifications");
+                buttonChar.addEventListener("characteristicvaluechanged", this.handleNotification.bind(this));
+                return this.sendOperation(buttonChar, OPERATIONS.BUTTON_COMMAND);
+            })
+            .then(() => {
+                this.log("sent dfu mode");
+                return new Promise((resolve, reject) => {
+                    device.addEventListener("gattserverdisconnected", event => {
+                        resolve();
+                    });
+                });
+            });
+        });
+    }
+
+    secureDfu.prototype.update = function(device, init, firmware) {
+        if (!device) throw new Error("Device not specified");
+        if (!init) throw new Error("Init not specified");
+        if (!firmware) throw new Error("Firmware not specified");
+
+        return this.connect(device)
+        .then(() => {
+            this.log("transferring init");
+            return this.transferInit(init);
         })
         .then(() => {
-            this.log("enabled control notifications");
-            this.controlChar.addEventListener("characteristicvaluechanged", this.handleNotification.bind(this));
-            return service.getCharacteristic(PACKET_UUID);
+            this.log("transferring firmware");
+            return this.transferFirmware(firmware);
         })
-        .then(characteristic => {
+        .then(() => {
+            this.log("complete, disconnecting...");
+            return new Promise((resolve, reject) => {
+                device.addEventListener("gattserverdisconnected", event => {
+                    this.log("disconnected");
+                    resolve();
+                });
+           });
+        });
+    }
+
+    secureDfu.prototype.connect = function(device) {
+        device.addEventListener("gattserverdisconnected", event => {
+            this.controlChar = null;
+            this.packetChar = null;
+        });
+
+        return this.gattConnect(device)
+        .then(characteristics => {
+            this.log(`found ${characteristics.length} characteristic(s)`);
+
+            this.packetChar = characteristics.find(characteristic => {
+                return (characteristic.uuid === PACKET_UUID);
+            });
+            if (!this.packetChar) throw new Error("Unable to find packet characteristic");
             this.log("found packet characteristic");
-            this.packetChar = characteristic;
-            this.connected = true;
+
+            this.controlChar = characteristics.find(characteristic => {
+                return (characteristic.uuid === CONTROL_UUID);
+            });
+            if (!this.controlChar) throw new Error("Unable to find control characteristic");
+            this.log("found control characteristic");
+
+            if (!this.controlChar.properties.notify && !this.controlChar.properties.indicate) {
+                throw new Error("Control characteristic does not allow notifications");
+            }
+            return this.controlChar.startNotifications();
+        })
+        .then(() => {
+            this.controlChar.addEventListener("characteristicvaluechanged", this.handleNotification.bind(this));
+            this.log("enabled control notifications");
+            return device;
         });
     };
 
+    secureDfu.prototype.gattConnect = function(device) {
+        return Promise.resolve()
+        .then(() => {
+            if (device.gatt.connected) return device.gatt;
+            return device.gatt.connect();
+        })
+        .then(server => {
+            this.log("connected to gatt server");
+            return server.getPrimaryService(SERVICE_UUID)
+            .catch(error => {
+                throw new Error("Unable to find DFU service");
+            });
+        })
+        .then(service => {
+            this.log("found DFU service");
+            return service.getCharacteristics();
+        });
+    }
+
     secureDfu.prototype.handleNotification = function(event) {
         let view = event.target.value;
 
-        if (view.getUint8(0) !== OPERATIONS.RESPONSE[0]) {
-            throw new Error("unrecognised control characteristic response notification");
+        if (OPERATIONS.RESPONSE.indexOf(view.getUint8(0)) < 0) {
+            throw new Error("Unrecognised control characteristic response notification");
         }
 
         let operation = view.getUint8(1);
@@ -213,12 +311,8 @@
         }
     };
 
-    secureDfu.prototype.sendOperation = function(operation, buffer) {
+    secureDfu.prototype.sendOperation = function(characteristic, operation, buffer) {
         return new Promise((resolve, reject) => {
-            if (!this.connected) throw new Error("device not connected");
-            if (!this.controlChar) throw new Error("control characteristic not found");
-            if (!this.packetChar) throw new Error("packet characteristic not found");
-
             let size = operation.length;
             if (buffer) size += buffer.byteLength;
 
@@ -234,72 +328,80 @@
                 reject: reject
             };
 
-            this.controlChar.writeValue(value);
+            characteristic.writeValue(value);
         });
     }
 
+    secureDfu.prototype.sendControl = function(operation, buffer) {
+        return this.sendOperation(this.controlChar, operation, buffer);
+    }
+
     secureDfu.prototype.transferInit = function(buffer) {
-        return this.sendOperation(OPERATIONS.SELECT_COMMAND)
+        return this.transfer(buffer, "init", OPERATIONS.SELECT_COMMAND, OPERATIONS.CREATE_COMMAND);
+    }
+
+    secureDfu.prototype.transferFirmware = function(buffer) {
+        return this.transfer(buffer, "firmware", OPERATIONS.SELECT_DATA, OPERATIONS.CREATE_DATA);
+    }
+
+    secureDfu.prototype.transfer = function(buffer, type, selectType, createType) {
+        return this.sendControl(selectType)
         .then(response => {
 
             let maxSize = response.getUint32(0, LITTLE_ENDIAN);
             let offset = response.getUint32(4, LITTLE_ENDIAN);
             let crc = response.getInt32(8, LITTLE_ENDIAN);
 
-            if (offset === buffer.byteLength && this.checkCrc(buffer, crc)) {
+            if (type === "init" && offset === buffer.byteLength && this.checkCrc(buffer, crc)) {
                 this.log("init packet already available, skipping transfer");
                 return;
             }
 
-            this.buffer = buffer;
-            return this.transferObject(OPERATIONS.CREATE_COMMAND, maxSize, offset);
+            this.progress = function(bytes) {
+                this.dispatchEvent({
+                    type: "progress",
+                    object: type,
+                    totalBytes: buffer.byteLength,
+                    currentBytes: bytes
+                });
+            }
+            this.progress(0);
+
+            return this.transferObject(buffer, createType, maxSize, offset);
         });
     }
 
-    secureDfu.prototype.transferFirmware = function(buffer) {
-        return this.sendOperation(OPERATIONS.SELECT_DATA)
-        .then(response => {
-
-            let maxSize = response.getUint32(0, LITTLE_ENDIAN);
-            let offset = response.getUint32(4, LITTLE_ENDIAN);
-            let crc = response.getInt32(8, LITTLE_ENDIAN);
-
-            this.buffer = buffer;
-            return this.transferObject(OPERATIONS.CREATE_DATA, maxSize, offset);
-        });
-    }
-
-    secureDfu.prototype.transferObject = function(createType, maxSize, offset) {
+    secureDfu.prototype.transferObject = function(buffer, createType, maxSize, offset) {
         let start = offset - offset % maxSize;
-        let end = Math.min(start + maxSize, this.buffer.byteLength);
+        let end = Math.min(start + maxSize, buffer.byteLength);
 
         let view = new DataView(new ArrayBuffer(4));
         view.setUint32(0, end - start, LITTLE_ENDIAN);
 
-        return this.sendOperation(createType, view.buffer)
+        return this.sendControl(createType, view.buffer)
         .then(response => {
-            let data = this.buffer.slice(start, end);
+            let data = buffer.slice(start, end);
             return this.transferData(data, start);
         })
         .then(() => {
-            return this.sendOperation(OPERATIONS.CACULATE_CHECKSUM);
+            return this.sendControl(OPERATIONS.CACULATE_CHECKSUM);
         })
         .then(response => {
             let crc = response.getInt32(4, LITTLE_ENDIAN);
             let transferred = response.getUint32(0, LITTLE_ENDIAN);
-            let data = this.buffer.slice(0, transferred);
+            let data = buffer.slice(0, transferred);
 
             if (this.checkCrc(data, crc)) {
                 this.log(`written ${transferred} bytes`);
                 offset = transferred;
-                return this.sendOperation(OPERATIONS.EXECUTE);
+                return this.sendControl(OPERATIONS.EXECUTE);
             } else {
                 this.log("object failed to validate");
             }
         })
         .then(() => {
-            if (end < this.buffer.byteLength) {
-                return this.transferObject(createType, maxSize, offset);
+            if (end < buffer.byteLength) {
+                return this.transferObject(buffer, createType, maxSize, offset);
             } else {
                 this.log("transfer complete");
             }
@@ -313,11 +415,7 @@
 
         return this.packetChar.writeValue(packet)
         .then(() => {
-            this.dispatchEvent({
-                type: "progress",
-                currentBytes: offset + end,
-                totalBytes: this.buffer.byteLength
-            });
+            this.progress(offset + end);
 
             if (end < data.byteLength) {
                 return this.transferData(data, offset, end);
diff --git a/examples/secure_dfu_web.html b/examples/secure_dfu_web.html
index e793f72..7b924e6 100644
--- a/examples/secure_dfu_web.html
+++ b/examples/secure_dfu_web.html
@@ -19,11 +19,11 @@
             font-weight: 600;
         }
         #drop {
-            margin: 40px auto;
-            max-width: 640px;
-            background-color: rgba(255, 255, 255, 0.10);
             position: relative;
-            padding: 100px 0px 70px;
+            margin: 40px auto;
+            max-width: 680px;
+            background-color: rgba(255, 255, 255, 0.10);
+            padding: 120px 0px 100px;
             outline: 2px dashed #072b44;
             outline-offset: -10px;
         }
@@ -33,50 +33,49 @@
         }
         #icon {
             width: 100%;
-            height: 40px;
             fill: #d7ecfb;
-            display: block;
-            margin-bottom: 40px;
+            margin-bottom: 30px;
+        }
+        #github {
+            fill: #d7ecfb;
+        }
+        #github:hover {
+            fill: #8bb5ba;
         }
         #file {
             width: 0.1px;
             height: 0.1px;
             opacity: 0;
-            overflow: hidden;
-            position: absolute;
             z-index: -1;
         }
         #label {
             cursor: pointer;
-            display: block;
         }
         #label:hover strong {
             color: #8bb5ba;
         }
-        #update {
+        #select {
             position: absolute;
             width: 100%;
-            z-index: 1;
             visibility: hidden;
         }
         #button {
             font-size: 12px;
-            color: #d5e8f1;
+            color: inherit;
             margin: 20px auto;
             border: 0px;
             background-color: #1b679c;
-            outline: none;
             height: 30px;
             padding: 0 30px;
             border-radius: 4px;
             text-transform: uppercase;
             cursor: pointer;
+            outline: none;
         }
         #button:hover {
             background: #2674ab;    
         }
         #status {
-            position: relative;
             margin: 20px auto;
             border: 1px solid #d7ecfb;
             width: 400px;
@@ -89,9 +88,9 @@
             height: 100%;
         }
         #transfer {
-            position: absolute;
-            line-height: 24px;
             width: 100%;
+            line-height: 24px;
+            margin-top: -24px;
         }
 	</style>
 </head>
@@ -109,16 +108,22 @@
             <span>or drag it here</span>
         </label>
 
-        <div id="update">
-            <button id="button">Update</button>
+        <div id="select">
+            <button id="button">Select Device</button>
         </div>
 
         <div id="status">
-            <div id="bar" />
-            <div id="transfer" />
+            <div id="bar"></div>
+            <div id="transfer"></div>
         </div>
     </div>
 
+    <a href="https://github.com/thegecko/web-bluetooth-dfu/">
+        <svg id="github" xmlns="http://www.w3.org/2000/svg" width="40" height="40" viewBox="0 0 16 16">
+            <path d="M8 0C3.58 0 0 3.58 0 8c0 3.54 2.29 6.53 5.47 7.59.4.07.55-.17.55-.38 0-.19-.01-.82-.01-1.49-2.01.37-2.53-.49-2.69-.94-.09-.23-.48-.94-.82-1.13-.28-.15-.68-.52-.01-.53.63-.01 1.08.58 1.23.82.72 1.21 1.87.87 2.33.66.07-.52.28-.87.51-1.07-1.78-.2-3.64-.89-3.64-3.95 0-.87.31-1.59.82-2.15-.08-.2-.36-1.02.08-2.12 0 0 .67-.21 2.2.82.64-.18 1.32-.27 2-.27.68 0 1.36.09 2 .27 1.53-1.04 2.2-.82 2.2-.82.44 1.1.16 1.92.08 2.12.51.56.82 1.27.82 2.15 0 3.07-1.87 3.75-3.65 3.95.29.25.54.73.54 1.48 0 1.07-.01 1.93-.01 2.2 0 .21.15.46.55.38A8.013 8.013 0 0 0 16 8c0-4.42-3.58-8-8-8z"/>
+        </svg>
+    </a>
+
     <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/crc-32/1.0.2/crc32.min.js"></script>
     <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jszip/3.1.3/jszip.min.js"></script>
     <script src="/dist/secure-dfu.js"></script>
@@ -126,7 +131,8 @@
     <script>
         let dropEl = document.getElementById("drop");
         let fileEl = document.getElementById("file");
-        let updateEl = document.getElementById("update");
+        let selectEl = document.getElementById("select");
+        let buttonEl = document.getElementById("button");
         let labelEl = document.getElementById("label");
         let statusEl = document.getElementById("status");
         let transferEl = document.getElementById("transfer");
@@ -135,22 +141,22 @@
         let package = null;
         let manifest = null;
 
-        function updateStatus(state) {
+        function setStatus(state) {
             labelEl.textContent = state;
         }
 
-        function updateTransfer(state) {
+        function setTransfer(state) {
             if (!state) {
                 statusEl.style.visibility = "hidden";
                 return;
             }
-            updateEl.style.visibility = "hidden";
+            selectEl.style.visibility = "hidden";
             statusEl.style.visibility = "visible";
             barEl.style.width = state.currentBytes / state.totalBytes * 100 + '%';
-            transferEl.textContent = `${state.currentBytes}/${state.totalBytes} bytes written`;
+            transferEl.textContent = `${state.currentBytes}/${state.totalBytes} ${state.object} bytes written`;
         }
 
-        function updatePackage(file) {
+        function setPackage(file) {
             if (!file) return;
 
             JSZip.loadAsync(file)
@@ -164,79 +170,91 @@
             })
             .then(content => {
                 manifest = JSON.parse(content).manifest;
-                updateStatus(`Package: ${file.name}`);
-                updateEl.style.visibility = "visible";
+                setStatus(`Firmware package: ${file.name}`);
+                selectEl.style.visibility = "visible";
             })
             .catch(error => {
-                updateEl.style.visibility = "hidden";
+                selectEl.style.visibility = "hidden";
                 statusEl.style.visibility = "hidden";
-                updateStatus(error);
+                setStatus(error);
             });
         }
 
-        function transfer() {
-            if (!package) return;
-            updateStatus(`Selecting device...`);
-            updateTransfer();
+        function selectDevice() {
+            setStatus("Selecting device...");
+            setTransfer();
 
             const dfu = new SecureDfu(CRC32.buf);
             dfu.addEventListener("log", event => {
                 console.log(event.message);
             });
             dfu.addEventListener("progress", event => {
-                updateTransfer(event);
+                setTransfer(event);
             });
 
-            dfu.requestDevice()
+            dfu.requestDevice(true)
             .then(device => {
-                return dfu.connect(device);
+                if (!device) {
+                    setStatus("Buttonless mode set, select device again");
+                    return;
+                }
+                return update(dfu, device);
             })
+            .catch(error => {
+                statusEl.style.visibility = "hidden";
+                setStatus(error);
+            });
+        }
+
+        function update(dfu, device) {
+            if (!package) return;
+
+            Promise.resolve()
             .then(() => {
                 for (type of ["softdevice", "bootloader", "softdevice_bootloader"]) {
                     if (manifest[type]) {
-                        return transferImage(dfu, manifest[type]);
+                        return updateFirmware(device, dfu, manifest[type], type);
                     }
                 }
             })
             .then(() => {
                 if (manifest.application) {
-                    return transferImage(dfu, manifest.application);
-                }                
+                    return updateFirmware(device, dfu, manifest.application, "application");
+                }
             })
             .then(() => {
-                updateStatus("Update complete!");
-                updateTransfer();
+                setStatus("Update complete!");
+                setTransfer();
             })
             .catch(error => {
                 statusEl.style.visibility = "hidden";
-                updateStatus(error);
+                setStatus(error);
             });
         }
 
-        function transferImage(dfu, manifest) {
+        function updateFirmware(device, dfu, manifest, type) {
+            let init = null;
+
             return package.file(manifest.dat_file).async("arraybuffer")
             .then(data => {
-                updateStatus(`Transferring init: ${manifest.dat_file}...`);
-                return dfu.transferInit(data);
-            })
-            .then(() => {
+                init = data;
                 return package.file(manifest.bin_file).async("arraybuffer");
             })
             .then(data => {
-                updateStatus(`Transferring firmware: ${manifest.bin_file}...`);
-                return dfu.transferFirmware(data);
+                setStatus(`Updating ${type}: ${manifest.bin_file}...`);
+                return dfu.update(device, init, data);
             });
         }
 
         fileEl.addEventListener("change", event => {
-            updatePackage(event.target.files[0]);                
+            setPackage(event.target.files[0]);
         });
 
         dropEl.addEventListener("drop", event => {
-            updatePackage(event.dataTransfer.files[0]);
+            setPackage(event.dataTransfer.files[0]);
         });
 
-        updateEl.addEventListener("click", transfer);
+        buttonEl.addEventListener("click", selectDevice);
 
         ["drag", "dragstart", "dragend", "dragover", "dragenter", "dragleave", "drop"].forEach(eventName => {
             dropEl.addEventListener(eventName, event => {
diff --git a/package.json b/package.json
index 3a6f6a0..bfc535b 100644
--- a/package.json
+++ b/package.json
@@ -20,14 +20,17 @@
     "nordic",
     "web-bluetooth"
   ],
+  "scripts": {
+    "example": "node examples/secure_dfu_node.js"
+  },
   "dependencies": {
-    "bleat": "^0.1.1",
-    "crc-32": "^1.0.2",
-    "jszip": "^3.1.3",
-    "progress": "^2.0.0"
+    "bleat": "^0.1.2"
   },
   "devDependencies": {
+    "crc-32": "^1.0.2",
     "gulp": "^3.9.1",
-    "gulp-jshint": "^1.9.0"
+    "gulp-jshint": "^1.9.0",
+    "jszip": "^3.1.3",
+    "progress": "^2.0.0"
   }
 }