diff --git a/README.rst b/README.rst
index df68cee..a6b9f98 100644
--- a/README.rst
+++ b/README.rst
@@ -261,3 +261,7 @@ application (and the "blank" white screen is a torch application):
 .. image:: res/LevelApp.png
    :alt: Shows a time as words in the wasp-os simulator
    :width: 179
+
+.. image:: res/BeaconApp.png
+   :alt: Flash the relatively powerful HRS LED repeatedly
+   :width: 179
\ No newline at end of file
diff --git a/apps/Beacon.py b/apps/Beacon.py
new file mode 100644
index 0000000..d8423cf
--- /dev/null
+++ b/apps/Beacon.py
@@ -0,0 +1,104 @@
+# SPDX-License-Identifier: LGPL-3.0-or-later
+# Copyright (C) 2021 Francesco Gazzetta
+"""Beacon application
+~~~~~~~~~~~~~~~~~~~~~
+
+Flash the relatively powerful HRS LED repeatedly, mostly for signaling purposes.
+
+Frequency and intensity can be changed.
+
+The blinking is handled by the HRS, so this app consumes very little power.
+With BLE and/or step counter disabled and blinking frequency set to the minimum,
+the watch's battery will last for many days.
+
+.. figure:: res/BeaconApp.png
+    :width: 179
+"""
+
+import wasp
+import machine
+from micropython import const
+
+class BeaconApp():
+    NAME = "Beacon"
+    # 2-bit RLE, 96x64, generated from res/beacon_icon.png, 336 bytes
+    ICON = (
+        b'\x02'
+        b'`@'
+        b'?\xff\x11@\xfcB?\x1dB\x80z\x82B?\x1aA'
+        b'\x86A?\x18A\x88A?\t\xc0\x18\xc3\nA\x8aA'
+        b'\n\xc3=\xc5\x04N\x04\xc5?\x06\xc3\x02A\xcaA\x02'
+        b'\xc3?\x10A\xcaA?\x08\xcb\x02A\xc3@\x1eD\xc3'
+        b'\x80\xfc\x81\x02\xcc9\xcb\x01\x81\xc4D\xc4\x81\x01\xcc?'
+        b'\x06\x81\xcc\x81?\x0f\xc3\x01\x81\xcc\x81\x01\xc3?\x06\xc5'
+        b'\x04\x8e\x04\xc5=\xc3\t\x81\xc0z\xcc\x81\t@\x18C'
+        b'?\x07\x81\xcc\x81?\x12\x81\xce\x81?\x11\x81\xce\x81?'
+        b'\x11\x81\xce\x81?\x11\x81\xce\x81?\x11\x81\xce\x81?\x11'
+        b'\x81\xce\x81?\x11\x81\xce\x81?\x10\x81\xd0\x81?\x0f\x81'
+        b'\xd0\x81?\x0f\x92?\x0f\x81\x80\x81\x90\xc0\xfc\xc1?\x0f'
+        b'\xc1\x90\xc1?\x0f\xc1\x90\xc1?\x0e\xc1\x92\xc1?\r\xc1'
+        b'\x92\xc1?\r\xc1\x92\xc1?\r\xc1\x92\xc1?\r\xc1\x92'
+        b'\xc1?\r\xc1\x92\xc1?\r\xc1\x92\xc1?\x0c\xc1\x94\xc1'
+        b'?\x0b\xd6?\x0b\xc1@zT\xc1?\x0b\xc1T\xc1?'
+        b'\x0b\xc1T\xc1?\x0b\xc1T\xc1?\n\xc1V\xc1?\t'
+        b'\xc1V\xc1?\t\xc1V\xc1?\t\xc1V\xc1?\t\xc1'
+        b'V\xc1?\t\xc1V\xc1?\t\xc1V\xc1?\x08\xda?'
+        b'\x07\xc1\x98\xc1?\x07\xc1\x98\xc1?\x07\xc1\x98\xc1?\x07'
+        b'\xc1\x98\xc1?\x07\xc1\x98\xc1?\x06\xc1\x9a\xc1?\x05\xc1'
+        b'\x9a\xc1?\x05\xc1\x9a\xc1?\x05\xdc?\xff\x04'
+    )
+
+
+    def __init__(self):
+        self._checkbox = wasp.widgets.Checkbox(10, 45, "Enable beacon")
+        self._slider_current = wasp.widgets.Slider(4, 10, 110, 0x27e4)
+        self._slider_wait_time = wasp.widgets.Slider(8, 10, 180)
+
+    def foreground(self):
+        wasp.system.bar.clock = True
+        self._draw()
+        wasp.system.request_event(wasp.EventMask.TOUCH)
+
+    def _draw(self):
+        draw = wasp.watch.drawable
+        draw.fill()
+        wasp.system.bar.draw()
+        self._checkbox.draw()
+        draw.string("Intensity:", 10, 85)
+        self._slider_current.draw()
+        draw.string("Frequency:", 10, 155)
+        self._slider_wait_time.draw()
+        self._draw_preview()
+
+    def touch(self, event):
+        if self._checkbox.touch(event):
+            if self._checkbox.state:
+                wasp.watch.hrs.enable()
+                wasp.watch.hrs.set_hwt(self._slider_wait_time.value)
+                wasp.watch.hrs.set_drive(self._slider_current.value)
+            else:
+                wasp.watch.hrs.disable()
+            self._checkbox.update()
+        elif event[2] >= 180:
+            if self._slider_wait_time.touch(event):
+                wasp.watch.hrs.set_hwt(self._slider_wait_time.value)
+                self._slider_wait_time.update()
+                self._draw_preview()
+        elif event[2] >= 110:
+            if self._slider_current.touch(event):
+                wasp.watch.hrs.set_drive(self._slider_current.value)
+                self._slider_current.update()
+                self._draw_preview()
+        wasp.system.bar.update()
+
+    def _draw_preview(self):
+        """
+        Draw a dashed line representing intensity and frequency
+        with thickness and separation of dashes
+        """
+        draw = wasp.watch.drawable
+        draw.fill(None, 10, 220, 227, 20)
+        x = 10
+        while x < 220:
+            wasp.watch.drawable.fill(0x27e4, x, 227, 8, (self._slider_current.value + 1) * 3)
+            x += (8 - self._slider_wait_time.value) * 8
diff --git a/docs/apps.rst b/docs/apps.rst
index 6432d3b..e6c0a63 100644
--- a/docs/apps.rst
+++ b/docs/apps.rst
@@ -45,6 +45,8 @@ Applications
 
 .. automodule:: apps.alarm
 
+.. automodule:: Beacon
+
 .. automodule:: apps.calc
 
 .. automodule:: apps.demo
diff --git a/res/BeaconApp.png b/res/BeaconApp.png
new file mode 100644
index 0000000..8fc4754
Binary files /dev/null and b/res/BeaconApp.png differ
diff --git a/res/beacon_icon.png b/res/beacon_icon.png
new file mode 100644
index 0000000..4bd99f9
Binary files /dev/null and b/res/beacon_icon.png differ
diff --git a/wasp/boards/simulator/watch.py b/wasp/boards/simulator/watch.py
index 900d1d6..860c414 100644
--- a/wasp/boards/simulator/watch.py
+++ b/wasp/boards/simulator/watch.py
@@ -159,6 +159,12 @@ class HRS():
         self._i = 0
         self._step = 1
 
+    def read_reg(self, addr):
+        pass
+
+    def write_reg(self, addr, val):
+        pass
+
     def enable(self):
         pass
 
@@ -178,6 +184,12 @@ class HRS():
 
         return d
 
+    def set_drive(self, drive):
+        pass
+
+    def set_hwt(self, t):
+        pass
+
 backlight = Backlight()
 spi = SPI(0)
 spi.init(polarity=1, phase=1, baudrate=8000000)
diff --git a/wasp/drivers/hrs3300.py b/wasp/drivers/hrs3300.py
index 80c8df0..c6027c4 100644
--- a/wasp/drivers/hrs3300.py
+++ b/wasp/drivers/hrs3300.py
@@ -13,10 +13,13 @@ _I2CADDR = const(0x44)
 _ID = const(0x00)
 _ENABLE = const(0x01)
 _ENABLE_HEN = const(0x80)
+_ENABLE_HWT = const(0x70)
+_ENABLE_PDRIVE1 = const(0x08)
 _C1DATAM = const(0x08)
 _C0DATAM = const(0x09)
 _C0DATAH = const(0x0a)
 _PDRIVER = const(0x0c)
+_PDRIVER_PDRIVE0 = const(0x40)
 _C1DATAH = const(0x0d)
 _C1DATAL = const(0x0e)
 _C0DATAL = const(0x0f)
@@ -88,11 +91,40 @@ class HRS3300:
         self.write_reg(_HGAIN, hgain << 2)
 
     def set_drive(self, drive):
+        """
+        Set LED drive current
+
+        Parameters:
+            drive (int) LED drive current
+                0 = 12.5 mA
+                1 = 20   mA
+                2 = 30   mA
+                3 = 40   mA
+        """
         en = self.read_reg(_ENABLE)
         pd = self.read_reg(_PDRIVER)
        
-        en = (en & 0xf7) | ((drive & 2) << 2)
-        pd = (pd & 0xbf) | ((drive & 1) << 6)
+        en = (en & ~_ENABLE_PDRIVE1 ) | ((drive & 2) << 2)
+        pd = (pd & ~_PDRIVER_PDRIVE0) | ((drive & 1) << 6)
 
         self.write_reg(_ENABLE, en)
         self.write_reg(_PDRIVER, pd)
+
+    def set_hwt(self, t):
+        """
+        Set wait time between each conversion cycle
+
+        Parameters:
+            t (int) Wait time between each conversion cycle
+                0 = 800   ms
+                1 = 400   ms
+                2 = 200   ms
+                3 = 100   ms
+                4 =  75   ms
+                5 =  50   ms
+                6 =  12.5 ms
+                7 =   0   ms
+        """
+        en = self.read_reg(_ENABLE)
+        en = (en & ~_ENABLE_HWT) | (t << 4)
+        self.write_reg(_ENABLE, en)
diff --git a/wasp/widgets.py b/wasp/widgets.py
index 556c7f5..9d80502 100644
--- a/wasp/widgets.py
+++ b/wasp/widgets.py
@@ -430,7 +430,9 @@ class Slider():
             v = 0
         elif v >= self._steps:
             v = self._steps - 1
+        changed = self.value != v
         self.value = v
+        return changed
 
 class Spinner():
     """A simple Spinner widget.