Add brightness config support

This is far from perfect, but its a start. Ideally, the value would be
set in the display component instead.

components/axp192/axp192.cpp

@@ -33,6 +33,8 @@ void AXP192Component::update() {
       }
       this->batterylevel_sensor_->publish_state(batterylevel);
     }
+
+    UpdateBrightness();
 }
 
 
@@ -157,14 +159,25 @@ void AXP192Component::ReadBuff( uint8_t Addr , uint8_t Size , uint8_t *Buff )
     this->read_bytes(Addr, Buff, Size);
 }
 
-void AXP192Component::ScreenBreath(uint8_t brightness)
+void AXP192Component::UpdateBrightness()
 {
-    if (brightness > 12) 
+    ESP_LOGD(TAG, "Brightness=%f (Curr: %f)", brightness_, curr_brightness_);
+    if (brightness_ == curr_brightness_)
     {
-        brightness = 12;
+        return;
+    }
+    curr_brightness_ = brightness_;
+
+    const uint8_t c_min = 7;
+    const uint8_t c_max = 12;
+    auto ubri = c_min + static_cast<uint8_t>(brightness_ * (c_max - c_min));
+    
+    if (ubri > c_max) 
+    {
+        ubri = c_max;
     }
     uint8_t buf = Read8bit( 0x28 );
-    Write1Byte( 0x28 , ((buf & 0x0f) | (brightness << 4)) );
+    Write1Byte( 0x28 , ((buf & 0x0f) | (ubri << 4)) );
 }
 
 bool AXP192Component::GetBatState()

components/axp192/axp192.h

@@ -25,6 +25,7 @@ namespace axp192 {
 class AXP192Component : public PollingComponent, public i2c::I2CDevice {
 public:
   void set_batterylevel_sensor(sensor::Sensor *batterylevel_sensor) { batterylevel_sensor_ = batterylevel_sensor; }
+  void set_brightness(float brightness) { brightness_ = brightness; }
 
   // ========== INTERNAL METHODS ==========
   // (In most use cases you won't need these)
@@ -35,6 +36,8 @@ public:
 
 protected:
     sensor::Sensor *batterylevel_sensor_;
+    float brightness_{1.0f};
+    float curr_brightness_{-1.0f};
 
     /**
      * LDO2: Display backlight
@@ -44,7 +47,7 @@ protected:
      * DCDC3: Use unknown
      */
     void  begin(bool disableLDO2 = false, bool disableLDO3 = false, bool disableRTC = false, bool disableDCDC1 = false, bool disableDCDC3 = false);
-    void  ScreenBreath(uint8_t brightness);
+    void  UpdateBrightness();
     bool  GetBatState();
     uint8_t  GetBatData();
   

components/axp192/sensor.py

@@ -1,9 +1,8 @@
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome.components import i2c, sensor
-from esphome.const import CONF_HUMIDITY, CONF_ID,\
-    CONF_BATTERY_LEVEL, CONF_TEMPERATURE, ICON_THERMOMETER, \
-    UNIT_PERCENT, UNIT_HECTOPASCAL, ICON_GAUGE, ICON_WATER_PERCENT, ICON_BATTERY
+from esphome.const import CONF_ID,\
+    CONF_BATTERY_LEVEL, CONF_BRIGHTNESS, UNIT_PERCENT, ICON_BATTERY
 
 DEPENDENCIES = ['i2c']
 
@@ -16,6 +15,7 @@ CONFIG_SCHEMA = cv.Schema({
     cv.Optional(CONF_BATTERY_LEVEL):
         sensor.sensor_schema(UNIT_PERCENT, ICON_BATTERY, 1).extend({
         }),
+    cv.Optional(CONF_BRIGHTNESS, default=1.0): cv.percentage,
 }).extend(cv.polling_component_schema('60s')).extend(i2c.i2c_device_schema(0x77))
 
 
@@ -28,3 +28,7 @@ def to_code(config):
         conf = config[CONF_BATTERY_LEVEL]
         sens = yield sensor.new_sensor(conf)
         cg.add(var.set_batterylevel_sensor(sens))
+
+    if CONF_BRIGHTNESS in config:
+        conf = config[CONF_BRIGHTNESS]
+        cg.add(var.set_brightness(conf))