diff --git a/apps/btadv/ChangeLog b/apps/btadv/ChangeLog
new file mode 100644
index 000000000..1a3bc1757
--- /dev/null
+++ b/apps/btadv/ChangeLog
@@ -0,0 +1 @@
+0.01: New app!
diff --git a/apps/btadv/app.js b/apps/btadv/app.js
new file mode 100644
index 000000000..494352f1c
--- /dev/null
+++ b/apps/btadv/app.js
@@ -0,0 +1,333 @@
+// TODO debounce
+
+const UPDATE_MILLISECONDS = 30 * 1000;
+
+let acc, bar, gps, hrm, mag;
+let curMenu; // acc | bar | gps | hrm | mag | main
+let updateInterval;
+let mainMenuScroll = 0;
+const settings = {
+  barEnabled: false,
+  gpsEnabled: false,
+  hrmEnabled: false,
+  magEnabled: false,
+};
+
+const showMainMenu = () => {
+  const onOff = b => b ? " (on)" : " (off)";
+  const mainMenu = {};
+
+  const showMenu = (menu, scroll, cur) => () => {
+    E.showMenu(menu);
+    mainMenuScroll = scroll;
+    curMenu = cur;
+  };
+
+  mainMenu[""] = {
+    "title": "--  btadv  --",
+    back: showMainMenu,
+    scroll: mainMenuScroll,
+  };
+
+  mainMenu["Acceleration"]                              = showMenu(accMenu, 0, "acc");
+  mainMenu["Barometer" + onOff(settings.barEnabled)]    = showMenu(barMenu, 1, "bar");
+  mainMenu["GPS" + onOff(settings.gpsEnabled)]          = showMenu(gpsMenu, 2, "gps");
+  mainMenu["Heart Rate" + onOff(settings.hrmEnabled)]   = showMenu(hrmMenu, 3, "hrm");
+  mainMenu["Magnetometer" + onOff(settings.magEnabled)] = showMenu(magMenu, 4, "mag");
+  mainMenu["Exit"]                                      = () => load(); // avoid `this`
+
+  E.showMenu(mainMenu);
+  curMenu = "main";
+};
+
+const accMenu = {
+  "": { "title" : "- Acceleration -" },
+  "Active": { value: "true (fixed)" },
+  "x": { value: null },
+  "y": { value: null },
+  "z": { value: null },
+};
+
+const barMenu = {
+  "": { "title" : "-  Barometer   -" },
+  "Active": {
+    value: settings.barEnabled,
+    onchange: v => { updateSetting('barEnabled', v); }
+  },
+  "Altitude": { value: null },
+  "Press": { value: null },
+  "Temp": { value: null },
+};
+
+const gpsMenu = {
+  "": { "title" : "-      GPS     -" },
+  "Active": {
+    value: settings.gpsEnabled,
+    onchange: v => { updateSetting('gpsEnabled', v); }
+  },
+  "Lat": { value: null },
+  "Lon": { value: null },
+  "Altitude": { value: null },
+  "Satellites": { value: null },
+  "HDOP": { value: null },
+};
+
+const hrmMenu = {
+  "": { "title" : "-  Heart Rate  -" },
+  "Active": {
+    value: settings.hrmEnabled,
+    onchange: v => { updateSetting('hrmEnabled', v); }
+  },
+  "BPM": { value: null },
+  "Confidence": { value: null },
+};
+
+const magMenu = {
+  "": { "title" : "- Magnetometer -" },
+  "Active": {
+    value: settings.magEnabled,
+    onchange: v => { updateSetting('magEnabled', v); }
+  },
+  "x": { value: null },
+  "y": { value: null },
+  "z": { value: null },
+  "Heading": { value: null },
+};
+
+const updateMenu = () => {
+  switch (curMenu) {
+    case "acc":
+      if (acc) {
+        accMenu.x.value = acc.x.toFixed(2);
+        accMenu.y.value = acc.y.toFixed(2);
+        accMenu.z.value = acc.z.toFixed(2);
+        E.showMenu(accMenu);
+      }
+      break;
+
+    case "bar":
+      if (bar) {
+        barMenu.Altitude.value = bar.altitude.toFixed(1) + 'm';
+        barMenu.Press.value = bar.pressure.toFixed(1) + 'mbar';
+        barMenu.Temp.value = bar.temperature.toFixed(1) + 'C';
+        E.showMenu(barMenu);
+      }
+      break;
+
+    case "gps":
+      if (gps) {
+        gpsMenu.Lat.value = gps.lat.toFixed(4);
+        gpsMenu.Lon.value = gps.lon.toFixed(4);
+        gpsMenu.Altitude.value = gps.alt + 'm';
+        gpsMenu.Satellites.value = gps.satellites;
+        gpsMenu.HDOP.value = (gps.hdop * 5).toFixed(1) + 'm';
+        E.showMenu(gpsMenu);
+      }
+      break;
+
+    case "hrm":
+      if (hrm) {
+        hrmMenu.BPM.value = hrm.bpm;
+        hrmMenu.Confidence.value = hrm.confidence + '%';
+        E.showMenu(hrmMenu);
+      }
+      break;
+
+    case "mag":
+      if (mag) {
+        magMenu.x.value = mag.x;
+        magMenu.y.value = mag.y;
+        magMenu.z.value = mag.z;
+        magMenu.Heading.value = mag.heading.toFixed(1);
+        E.showMenu(magMenu);
+      }
+      break;
+  }
+};
+
+const updateBleAdvert = () => {
+  if (!Bangle.bleAdvert)
+    Bangle.bleAdvert = {};
+
+  // const data = [ APP_ADVERTISING_DATA ]; // Always advertise at least app name
+
+  // if (bar) {
+  //   data.push(encodeBarServiceData(bar));
+  //   bar = undefined;
+  // }
+
+  // if (gps && gps.lat && gps.lon) {
+  //   data.push(encodeGpsServiceData(gps));
+  //   gps = undefined;
+  // }
+
+  if (hrm) {
+    Bangle.bleAdvert[0x180d] = undefined; // Advertise HRM
+
+    // hack
+    if (NRF.getSecurityStatus().connected) {
+      NRF.updateServices({
+        0x180d: {
+          0x2a37: {
+            value: [0, hrm.bpm],
+            notify: true,
+          }
+        }
+      })
+      console.log("updated hrm");
+      return;
+    }
+
+    // data.push({ 0x2a37: [ 0, hrm.bpm ] });
+    // hrm = undefined;
+  }
+
+  // if (mag) {
+  //   data.push(encodeMagServiceData(mag));
+  //   mag = undefined;
+  // }
+
+  const interval = UPDATE_MILLISECONDS / data.length;
+
+  NRF.setAdvertising(
+    Bangle.bleAdvert,
+    {
+      interval,
+    },
+  );
+};
+
+// {
+//   flags: u8,
+//   bytes: [u8...]
+// }
+// flags {
+//   1 << 0: 16bit bpm
+//   1 << 1: sensor contact available
+//   1 << 2: sensor contact boolean
+//   1 << 3: energy expended, next 16 bits
+//   1 << 4: "rr" data available, u16s, intervals
+// }
+const encodeHrm = () => [0, hrm ? hrm.bpm : 0];
+
+// TODO: emit this via set/updateServices
+const encodeBarServiceData = data => {
+  const t = toByteArray(Math.round(data.temperature * 100), 2, true);
+  const p = toByteArray(Math.round(data.pressure * 1000), 4, false);
+  const e = toByteArray(Math.round(data.altitude * 100), 3, true);
+
+  return [
+      0x02, 0x01, 0x06,                               // Flags
+      0x05, 0x16, 0x6e, 0x2a, t[0], t[1],             // Temperature
+      0x07, 0x16, 0x6d, 0x2a, p[0], p[1], p[2], p[3], // Pressure
+      0x06, 0x16, 0x6c, 0x2a, e[0], e[1], e[2]        // Elevation
+  ];
+};
+
+const encodeGpsServiceData = data => {
+  const s = toByteArray(Math.round(1000 * data.speed / 36), 2, false);
+  const lat = toByteArray(Math.round(data.lat * 10000000), 4, true);
+  const lon = toByteArray(Math.round(data.lon * 10000000), 4, true);
+  const e = toByteArray(Math.round(data.alt * 100), 3, true);
+  const h = toByteArray(Math.round(data.course * 100), 2, false);
+
+  return [
+      0x02, 0x01, 0x06, // Flags
+      0x14, 0x16, 0x67, 0x2a, 0x9d, 0x02, s[0], s[1], lat[0], lat[1], lat[2],
+      lat[3], lon[0], lon[1], lon[2], lon[3], e[0], e[1], e[2], h[0], h[1]
+                        // Location and Speed
+  ];
+};
+
+const encodeMagServiceData = data => {
+  const x = toByteArray(data.x, 2, true);
+  const y = toByteArray(data.y, 2, true);
+  const z = toByteArray(data.z, 2, true);
+
+  return [
+      0x02, 0x01, 0x06,                                          // Flags
+      0x09, 0x16, 0xa1, 0x2a, x[0], x[1], y[0], y[1], z[0], z[1] // Mag 3D
+  ];
+};
+
+const toByteArray = (value, numberOfBytes, isSigned) => {
+  const byteArray = new Array(numberOfBytes);
+
+  if(isSigned && (value < 0)) {
+    value += 1 << (numberOfBytes * 8);
+  }
+
+  for(let index = 0; index < numberOfBytes; index++) {
+    byteArray[index] = (value >> (index * 8)) & 0xff;
+  }
+
+  return byteArray;
+};
+
+const enableSensors = () => {
+  Bangle.setBarometerPower(settings.barEnabled, "btadv");
+  Bangle.setGPSPower(settings.gpsEnabled, "btadv");
+  Bangle.setHRMPower(settings.hrmEnabled, "btadv");
+  Bangle.setCompassPower(settings.magEnabled, "btadv");
+};
+
+const updateSetting = (name, value) => {
+  settings[name] = value;
+  //require('Storage').writeJSON(SETTINGS_FILENAME, settings);
+  enableSensors();
+};
+
+// ----------------------------
+
+NRF.setServices(
+  {
+    0x180d: {
+      0x2a37: {
+        value: encodeHrm(),
+        readable: true,
+        notify: true,
+        //indicate: true, // notify + ACK
+      },
+    },
+  },
+  {
+    advertise: [
+      '180d',
+    ]
+  },
+);
+
+const updateServices = () => {
+  NRF.updateServices({
+    0x180d: {
+      0x2a37: {
+        value: encodeHrm(),
+        notify: true,
+      }
+    }
+  });
+};
+
+Bangle.on('accel', newAcc => acc = newAcc);
+Bangle.on('pressure', newBar => bar = newBar);
+Bangle.on('GPS', newGps => gps = newGps);
+Bangle.on('HRM', newHrm => hrm = newHrm);
+Bangle.on('mag', newMag => mag = newMag);
+
+enableSensors();
+showMainMenu();
+
+// setInterval(updateAdvert, 10000);
+setInterval(updateMenu, 1000);
+
+NRF.on("connect", () => {
+  updateInterval = setInterval(updateServices, 1000);
+});
+NRF.on("disconnect", () => {
+  clearInterval(updateInterval);
+  updateInterval = undefined;
+});
+
+// FIXME: ui overlap
+// Bangle.loadWidgets();
+// Bangle.drawWidgets();
diff --git a/apps/btadv/metadata.json b/apps/btadv/metadata.json
new file mode 100644
index 000000000..73ff04e52
--- /dev/null
+++ b/apps/btadv/metadata.json
@@ -0,0 +1,13 @@
+{
+  "id": "btadv",
+  "name": "Export real-time sensor data over BLE",
+  "version": "0.01",
+  "description": "Advertise & export live heart rate, accel, pressure, GPS & mag data over bluetooth",
+  "icon": "heartrate.png",
+  "tags": "health,tool,sensors,bluetooth",
+  "supports": ["BANGLEJS2"],
+  "storage": [
+    {"name":"btadv.app.js","url":"app.js"},
+    {"name":"btadv.img","url":"icon.js","evaluate":true}
+  ]
+}