Implemented the slider sensor, which is used to publish a slider level when the slider is touched. The example yaml files now use this sensor to update the brightness of the LEDs.

binary_sensor/__init__.py

@@ -1,8 +1,7 @@
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome.components import binary_sensor
-#from esphome import automation
-from esphome.const import CONF_DEVICE_CLASS, CONF_ID
+from esphome.const import CONF_ID
 from .. import (
     bs2_ns, CODEOWNERS,
     CONF_FRONT_PANEL_HAL_ID, FrontPanelHAL
@@ -21,7 +20,7 @@ PARTS = {
 
 def validate_part(value):
     value = cv.string(value)
-    return cv.enum(PARTS, upper=True)(value)
+    return cv.enum(PARTS, upper=True, space='_')(value)
 
 YeelightBS2Button = bs2_ns.class_("YeelightBS2Button", binary_sensor.BinarySensor, cg.Component)
 
@@ -39,5 +38,5 @@ def to_code(config):
     yield binary_sensor.register_binary_sensor(var, config)
 
     front_panel_hal_var = yield cg.get_variable(config[CONF_FRONT_PANEL_HAL_ID])
-    cg.add(var.set_front_panel_hal(front_panel_hal_var))
+    cg.add(var.set_parent(front_panel_hal_var))
     cg.add(var.set_part(config[CONF_PART]))

binary_sensor/button.h → binary_sensor/binary_sensor.h

@@ -14,7 +14,7 @@ namespace bs2 {
  */
 class YeelightBS2Button : public binary_sensor::BinarySensor, public Component {
 public:
-    void set_front_panel_hal(FrontPanelHAL *front_panel) {
+    void set_parent(FrontPanelHAL *front_panel) {
         front_panel_ = front_panel;
     }
 
@@ -24,12 +24,15 @@ public:
 
     void setup() {
         ESP_LOGCONFIG(TAG, "Setting up binary_sensor ...");
-        ESP_LOGCONFIG(TAG, "  Part id: %d", part_);
+        ESP_LOGCONFIG(TAG, "  Part: %s (id %d)", 
+            (part_ == 1 ? "power button" :
+             part_ == 2 ? "color button" :
+             part_ == 3 ? "slider" : "any"),
+            part_);
 
         front_panel_->add_on_event_callback(
             [this](EVENT ev) {
                 // Filter events by part, when requested.
-                ESP_LOGI(TAG, "FILTER event=%d, part=%d", ev, part_);
                 if (part_ > 0) {
                     if ((ev & FLAG_PART_MASK) != (part_ << FLAG_PART_SHIFT)) {
                         return;

doc/example-full.yaml

@@ -73,12 +73,22 @@ light:
           transition_length: 3s
           update_interval: 3s
 
-# An implementation for the power button: touch to toggle the light.
+# The binary sensor is used to handle front panel touch events.
 binary_sensor:
   - platform: yeelight_bs2
     id: ${name}_power_button
-    part: POWER_BUTTON
+    part: power button
     on_press:
       then:
         - light.toggle: ${name}
 
+# The sensor is used to publish a slider level when the slider is touched.
+sensor:
+  - platform: yeelight_bs2
+    id: ${name}_slider_level
+    on_value:
+      then:
+        - light.turn_on:
+            id: ${name}
+            brightness: !lambda return x;
+

doc/example.yaml

@@ -48,11 +48,23 @@ light:
           transition_length: 3s
           update_interval: 3s
 
+# The binary sensor is used to handle front panel touch events.
 binary_sensor:
   - platform: yeelight_bs2
     id: ${name}_power_button
-    part: POWER_BUTTON
+    part: power button
     on_press:
       then:
         - light.toggle: ${name}
 
+# The sensor is used to publish a slider level when the slider is touched.
+sensor:
+  - platform: yeelight_bs2
+    id: ${name}_slider_level
+    on_value:
+      then:
+        - light.turn_on:
+            id: ${name}
+            brightness: !lambda return x;
+
+

light/__init__.py

@@ -36,7 +36,7 @@ def to_code(config):
     yield light.register_light(var, config)
 
     light_hal_var = yield cg.get_variable(config[CONF_LIGHT_HAL_ID])
-    cg.add(var.set_light_hal(light_hal_var))
+    cg.add(var.set_parent(light_hal_var))
 
     for conf in config.get(CONF_ON_BRIGHTNESS, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)

light/light_output.h

@@ -20,7 +20,7 @@ namespace bs2 {
  */
 class YeelightBS2LightOutput : public Component, public light::LightOutput {
 public:
-    void set_light_hal(LightHAL *light) { light_ = light; }
+    void set_parent(LightHAL *light) { light_ = light; }
 
     /**
      * Returns a LightTraits object, which is used to explain to the outside

sensor/__init__.py

@@ -0,0 +1,29 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import sensor
+from esphome.const import CONF_ID, CONF_FORCE_UPDATE
+from .. import (
+    bs2_ns, CODEOWNERS,
+    CONF_FRONT_PANEL_HAL_ID, FrontPanelHAL
+)
+
+AUTO_LOAD = ["yeelight_bs2"]
+
+YeelightBS2SliderSensor = bs2_ns.class_(
+    "YeelightBS2SliderSensor", sensor.Sensor, cg.Component)
+
+CONFIG_SCHEMA = sensor.SENSOR_SCHEMA.extend(
+    {
+        cv.GenerateID(): cv.declare_id(YeelightBS2SliderSensor),
+        cv.GenerateID(CONF_FRONT_PANEL_HAL_ID): cv.use_id(FrontPanelHAL),
+        cv.Optional(CONF_FORCE_UPDATE, default=True): cv.boolean,
+    }
+).extend(cv.COMPONENT_SCHEMA)
+
+def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+    yield cg.register_component(var, config)
+    yield sensor.register_sensor(var, config)
+
+    front_panel_hal_var = yield cg.get_variable(config[CONF_FRONT_PANEL_HAL_ID])
+    cg.add(var.set_parent(front_panel_hal_var))

sensor/sensor.h

@@ -0,0 +1,60 @@
+#pragma once 
+
+#include <cmath>
+#include "../common.h"
+#include "../front_panel_hal.h"
+#include "esphome/components/sensor/sensor.h"
+
+namespace esphome {
+namespace yeelight {
+namespace bs2 {
+
+/**
+ * A sensor for the slider on the Yeelight Bedside Lamp 2.
+ *
+ * This sensor publishes the level at which the slider was touched, so it
+ * can be used to implement automations.  Note that it does not represent
+ * the brightness of the LED lights (this is implemented by the light output
+ * component), nor the level as displayed by the slider using the front
+ * panel light (this is implemented by the slider light component).
+ */
+class YeelightBS2SliderSensor : public sensor::Sensor, public Component {
+public:
+    void set_parent(FrontPanelHAL *front_panel) {
+        front_panel_ = front_panel;
+    }
+
+    void setup() {
+        ESP_LOGCONFIG(TAG, "Setting up slider sensor ...");
+
+        front_panel_->add_on_event_callback(
+            [this](EVENT ev) {
+                if ((ev & FLAG_PART_MASK) == FLAG_PART_SLIDER) {
+                    auto level = (ev & FLAG_LEVEL_MASK) >> FLAG_LEVEL_SHIFT; 
+
+                    // Slider level 1 is really hard to touch. It is between
+                    // the power button and the slider space, so it doesn't
+                    // look like this one was ever meant to be used, or that
+                    // the design was faulty on this. Therefore, level 1 is
+                    // ignored here.
+                    level = max(1.0f, level - 1.0f);
+
+                    // Convert the slider level to a float between 0.01 and
+                    // 1.00, which is useful as a representation for a
+                    // brightness value. The input level is now between
+                    // 1 and 20.
+                    auto publish_level = max(0.01f, (level-1.0f) * (1.00f / 19.0f));
+                    
+                    this->publish_state(publish_level); 
+                }
+            }
+        );
+    }
+
+protected:
+    FrontPanelHAL *front_panel_;
+};
+    
+} // namespace bs2
+} // namespace yeelight
+} // namespace esphome