[Fingerprint_grow] Add description for Sleep Mode Feature (#3558)

components/fingerprint_grow.rst

@@ -38,6 +38,11 @@ If available on your reader model, it's recommended to connect 3.3VT (touch indu
     # Declare Grow Fingerprint Reader
     fingerprint_grow:
       sensing_pin: GPIO12
+      sensor_power_pin:
+          number: GPIO18
+          inverted: true
+      idle_period_to_sleep: 5s
+
       on_finger_scan_start:
         ...
       on_finger_scan_matched:
@@ -66,8 +71,10 @@ Base Configuration:
 - **uart_id** (*Optional*, :ref:`config-id`): Manually specify the ID of the UART hub.
 - **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for code generation.
 - **sensing_pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): Pin connected to the reader's finger detection signal (WAKEUP) output.
+- **sensor_power_pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): Output pin responsible for toogling the sensor power on and off.
 - **password** (*Optional*, int): Password to use for authentication. Defaults to ``0x00``.
 - **new_password** (*Optional*, int): Sets a new password to use for authentication. See :ref:`fingerprint_grow-set_new_password` for more information.
+- **idle_period_to_sleep** (*Optional*, :ref:`config-time`): The sensor idle period to wait before powering it off (sleep). Defaults to ``5s``. See :ref:`fingerprint_grow-sleep_mode` for more information.
 - **on_finger_scan_start** (*Optional*, :ref:`Automation <automation>`): An action to be performed when the finger touches the sensor. See :ref:`fingerprint_grow-on_finger_scan_start`.
 - **on_finger_scan_matched** (*Optional*, :ref:`Automation <automation>`): An action to be performed when an enrolled fingerprint is scanned. See :ref:`fingerprint_grow-on_finger_scan_matched`.
 - **on_finger_scan_unmatched** (*Optional*, :ref:`Automation <automation>`): An action to be performed when an unknown fingerprint is scanned. See :ref:`fingerprint_grow-on_finger_scan_unmatched`.
@@ -127,6 +134,32 @@ Sensor
   - **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for code generation.
   - All other options from :ref:`Sensor <config-sensor>`.
 
+.. _fingerprint_grow-sleep_mode:
+
+Sleep Mode
+----------
+The sensor idle power consumption is roughly 20mA. If you plan to keep the device running continuously, it is wise to implement the Sleep Mode, which puts the sensor to sleep (power off) a few seconds after the last communication (configurable with ``idle_period_to_sleep``). It can only be implemented along with the Touch Sensing Feature, since it uses the touch feedback to wake up the sensor.
+To implement this feature, you will need one more free GPIO pin to toggle the sensor power on and off and two external components: a 10kOhms resistor and a PNP transistor (like a BC327).
+
+This is a wiring example for the R503 and below you can find the respective configuration:
+
+.. figure:: images/fingeprint_grow-sleep_mode_wiring.jpg
+    :align: center
+    :width: 50.0%
+
+.. code-block:: yaml
+
+    uart:
+      rx_pin: GPIO16
+      tx_pin: GPIO17
+      baud_rate: 57600
+        
+    fingerprint_grow:
+      sensing_pin: GPIO4
+      sensor_power_pin:
+          number: GPIO18
+          inverted: true
+      idle_period_to_sleep: 5s
 
 .. _fingerprint_grow-set_new_password: