Added Etekcity Voltson cookbook (#628)

* Added Etekcity Voltson cookbook

* added esw01-eu images

* Added cookbook link

* Added esw01-eu cookbook image for index

* Removed direct docu links

cookbook/esw01-eu.rst

@@ -0,0 +1,121 @@
+Etekcity Voltson (ESW01-EU)
+===========================
+
+.. seo::
+    :description: Configure an Etekcity Voltson and calculate the missing current sensor
+    :image: esw01-eu.jpg
+    :keywords: Etekcity, Voltson, ESW01, ESW01-EU, HLW8012, Home Assistant, ESPHome
+
+
+The Etekcity Voltson brings a 10A relay, two LEDs (blue and yellow), a push button and a :doc:`/components/sensor/hlw8012`
+in a very small package and at a reasonable price.
+
+.. note::
+
+    There are quite a few hardware revisions out there. Also reginal versions like US, UK and EU are different.
+
+Flashing
+--------
+
+Opening the case for flashing varies a lot for different hardware revisions. Mine was easy as it had two tiny T5 Torx screws in the front and four Philipps screws inside.
+Once you have opened the case, remove the PCB from it and attach your TTL as follows:
+
+5V and GND go to the bottom:
+
+.. figure:: images/esw01-eu-pcb-bottom.jpg
+    :align: center
+    :width: 75.0%
+
+On the opposite side, T12 is TX, T13 is RX. During boot you need to connect T11 and T16 pads to GND. Easiest is to flash with pogo pins.
+
+.. figure:: images/esw01-eu-pcb-top.jpg
+    :align: center
+    :width: 75.0%
+
+Configuration
+-------------
+
+As the Voltson has its SEL pin permanently pulled high, we are unable to switch from voltage measurement to current measurement.
+This will be circumvented by defining the initial mode to be voltage measurement (see :doc:`/components/sensor/hlw8012` documentation)
+and calculating the current with `Ohm's law <https://en.wikipedia.org/wiki/Ohm%27s_law>`_: ``P (watts) = V (volts) x I (amps)``
+
+.. code-block:: yaml
+
+    esphome:
+      name: voltson
+      platform: ESP8266
+      board: esp01_1m
+
+    ### you wifi and other settings here ###
+
+    ### pins ###
+    # D1 GPIO5  | LED blue    | status_led
+    # D0 GPIO16 | LED yellow  | led1
+    # D5 GPIO14 | SW1         | button1
+    # D2 GPIO4  | REL1        | relay1
+    # D6 GPIO12 | HLW8012/CF1 | cf1_pin
+    # D7 GPIO13 | HLW8012/CF  | cf_pin
+
+    status_led:
+      pin: 
+        number: GPIO5
+
+    output:
+    - platform: gpio
+      id: relay1
+      pin: GPIO4
+    - platform: gpio
+      id: led1
+      pin: GPIO16
+
+    switch:
+    - platform: output
+      name: "Voltson Relay"
+      id: switch1
+      output: relay1
+      on_turn_on:
+        - output.turn_on: led1
+      on_turn_off:
+        - output.turn_off: led1
+
+    binary_sensor:
+      - platform: gpio
+        id: button1
+        pin:
+          number: GPIO14
+          mode: INPUT_PULLUP
+          inverted: true
+        on_press:
+          - switch.toggle: switch1
+
+    sensor:
+      - platform: hlw8012
+        sel_pin: 0   # not connected
+        cf_pin: GPIO13
+        cf1_pin: GPIO12
+        voltage:
+          id: hlw8012_voltage
+          name: "HLW8012 Voltage"
+        power:
+          id: hlw8012_power
+          name: "HLW8012 Power"
+          on_value:
+            - sensor.template.publish:
+                id: hlw8012_current_calculated
+                state: !lambda 'return id(hlw8012_power).state / id(hlw8012_voltage).state;'
+        update_interval: 10s
+        initial_mode: VOLTAGE
+        change_mode_every: 4294967295 # basically never
+      - platform: template
+        id: hlw8012_current_calculated
+        name: "HLW8012 Current (calculated)"
+        unit_of_measurement: A
+        accuracy_decimals: 2
+
+
+
+See Also
+--------
+
+- :doc:`/components/sensor/hlw8012`
+- :ghedit:`Edit`

index.rst

@@ -370,6 +370,7 @@ Cookbook
     Mirabella Genio Bulb, cookbook/mirabella-genio-bulb, cookbook-mirabella-genio-b22-rgbw.jpg
     Garage Door, cookbook/garage-door, window-open.svg
     Brilliant / Mirabella Genio Smart Plugs, cookbook/brilliant-mirabella-genio-smart-plugs, cookbook-brilliant-mirabella-genio-smart-plugs.jpg
+    Etekcity Voltson (ESW01-EU) , cookbook/esw01-eu, esw01-eu.jpg
     Zemismart RGBW Downlights, cookbook/zemismart-rgbw-downlights, cookbook-zemismart-rgbw-downlight.jpg
     Teckin SB50, cookbook/teckin_sb50, teckin_sb50.jpg