Added a binary sensor component, which can be used to handle touch/release events for the parts of the front panel (power button, color button and slider). Note that for the slider, this binary_sensor only detects the touch events. This cannot be used for detecting the actual slider level that was touch. For that purpose, a separate sensor will be created.

binary_sensor/__init__.py

@@ -0,0 +1,43 @@
+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 .. import (
+    bs2_ns, CODEOWNERS,
+    CONF_FRONT_PANEL_HAL_ID, FrontPanelHAL
+)
+
+AUTO_LOAD = ["yeelight_bs2"]
+
+CONF_PART = "part"
+
+PARTS = {
+    "ANY"          : 0,
+    "POWER_BUTTON" : 1,
+    "COLOR_BUTTON" : 2,
+    "SLIDER"       : 3.
+}
+
+def validate_part(value):
+    value = cv.string(value)
+    return cv.enum(PARTS, upper=True)(value)
+
+YeelightBS2Button = bs2_ns.class_("YeelightBS2Button", binary_sensor.BinarySensor, cg.Component)
+
+CONFIG_SCHEMA = binary_sensor.BINARY_SENSOR_SCHEMA.extend(
+    {
+        cv.GenerateID(): cv.declare_id(YeelightBS2Button),
+        cv.GenerateID(CONF_FRONT_PANEL_HAL_ID): cv.use_id(FrontPanelHAL),
+        cv.Optional(CONF_PART, default="ANY"): validate_part,
+    }
+).extend(cv.COMPONENT_SCHEMA)
+
+def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+    yield cg.register_component(var, 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_part(config[CONF_PART]))

binary_sensor/button.h

@@ -0,0 +1,52 @@
+#pragma once 
+
+#include "../common.h"
+#include "../front_panel_hal.h"
+#include "esphome/components/binary_sensor/binary_sensor.h"
+
+namespace esphome {
+namespace yeelight {
+namespace bs2 {
+
+/**
+ * This class implements a binary sensor for the buttons on the
+ * Yeelight Bedside Lamp 2.
+ */
+class YeelightBS2Button : public binary_sensor::BinarySensor, public Component {
+public:
+    void set_front_panel_hal(FrontPanelHAL *front_panel) {
+        front_panel_ = front_panel;
+    }
+
+    void set_part(int part) {
+        part_ = part;
+    }
+
+    void setup() {
+        ESP_LOGCONFIG(TAG, "Setting up binary_sensor ...");
+        ESP_LOGCONFIG(TAG, "  Part id: %d", 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;
+                    }
+                }
+                // Publish the new state, based on the touch/release status..
+                auto on_or_off = (ev & FLAG_TYPE_MASK) == FLAG_TYPE_TOUCH;
+                this->publish_state(on_or_off); 
+            }
+        );
+    }
+
+protected:
+    FrontPanelHAL *front_panel_;
+    EVENT part_;
+};
+    
+} // namespace bs2
+} // namespace yeelight
+} // namespace esphome

front_panel_hal.h

@@ -54,17 +54,20 @@ static const EVENT FLAG_INIT          = 0b0000000000;
 static const EVENT FLAG_ERR           = 0b0000000000;
 static const EVENT FLAG_OK            = 0b0000000001;
 
+static const EVENT FLAG_PART_SHIFT    = 1;
 static const EVENT FLAG_PART_MASK     = 0b0000000110;
 static const EVENT FLAG_PART_UNKNOWN  = 0b0000000000;
 static const EVENT FLAG_PART_POWER    = 0b0000000010;
 static const EVENT FLAG_PART_COLOR    = 0b0000000100;
 static const EVENT FLAG_PART_SLIDER   = 0b0000000110;
 
+static const EVENT FLAG_TYPE_SHIFT    = 3;
 static const EVENT FLAG_TYPE_MASK     = 0b0000011000;
 static const EVENT FLAG_TYPE_UNKNOWN  = 0b0000000000;
 static const EVENT FLAG_TYPE_TOUCH    = 0b0000001000;
 static const EVENT FLAG_TYPE_RELEASE  = 0b0000010000;
 
+static const EVENT FLAG_LEVEL_SHIFT   = 5;
 static const EVENT FLAG_LEVEL_MASK    = 0b1111100000;
 static const EVENT FLAG_LEVEL_UNKNOWN = 0b0000000000;
 
@@ -110,7 +113,7 @@ public:
                     return error_(ev, m, "out of bounds slider value");
                 } else {
                     auto level = 0x17 - m[5];
-                    ev |= (level << 5);
+                    ev |= (level << FLAG_LEVEL_SHIFT);
                 }
                 break;
             default:
@@ -143,7 +146,7 @@ protected:
             (has_(ev, FLAG_TYPE_MASK, FLAG_TYPE_TOUCH) ? "touch" :
              has_(ev, FLAG_TYPE_MASK, FLAG_TYPE_RELEASE) ? "release" : "n/a"));
         if (has_(ev, FLAG_PART_MASK, FLAG_PART_SLIDER)) {
-            auto level = (ev & FLAG_LEVEL_MASK) >> 5;
+            auto level = (ev & FLAG_LEVEL_MASK) >> FLAG_LEVEL_SHIFT;
             if (level > 0) {
                 ESP_LOGE(TAG, "  Parsed slider level: %d", level);
             }