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.. _4.1.11_py:

4.1.11 Battery Indicator
===================================

Introduction
--------------

In this project, we will make a battery indicator device that can
visually display the battery level on the LED Bargraph.

Required Components
------------------------------

In this project, we need the following components.

.. image:: ../img/list_Battery_Indicator.png
    :align: center

It's definitely convenient to buy a whole kit, here's the link: 

.. list-table::
    :widths: 20 20 20
    :header-rows: 1

    *   - Name	
        - ITEMS IN THIS KIT
        - LINK
    *   - Raphael Kit
        - 337
        - |link_Raphael_kit|

You can also buy them separately from the links below.

.. list-table::
    :widths: 30 20
    :header-rows: 1

    *   - COMPONENT INTRODUCTION
        - PURCHASE LINK

    *   - :ref:`cpn_gpio_extension_board`
        - |link_gpio_board_buy|
    *   - :ref:`cpn_breadboard`
        - |link_breadboard_buy|
    *   - :ref:`cpn_wires`
        - |link_wires_buy|
    *   - :ref:`cpn_resistor`
        - |link_resistor_buy|
    *   - :ref:`cpn_bar_graph`
        - \-
    *   - :ref:`cpn_adc0834`
        - \-

Schematic Diagram
-------------------

============ ======== ======== ===
T-Board Name physical wiringPi BCM
GPIO17       Pin 11   0        17
GPIO18       Pin 12   1        18
GPIO27       Pin 13   2        27
GPIO25       Pin 22   6        25
GPIO12       Pin 32   26       12
GPIO16       Pin 36   27       16
GPIO20       Pin 38   28       20
GPIO21       Pin 40   29       21
GPIO5        Pin 29   21       5
GPIO6        Pin 31   22       6
GPIO13       Pin 33   23       13
GPIO19       Pin 35   24       19
GPIO26       Pin 37   25       26
============ ======== ======== ===

.. image:: ../img/Schematic_three_one5.png
   :align: center

Experimental Procedures
-------------------------

**Step 1:** Build the circuit.

.. image:: ../img/image248.png

**Step 2:** Go to the folder of the code.

.. raw:: html

   <run></run>

.. code-block::

    cd ~/raphael-kit/python/

**Step 3:** Run the executable file.

.. raw:: html

   <run></run>

.. code-block::

    sudo python3 4.1.11_BatteryIndicator.py

After the program runs, give the 3rd pin of ADC0834 and the GND a
lead-out wire separately and then lead them to the two poles of a
battery separately. You can see the corresponding LED on the LED
Bargraph is lit up to display the power level (measuring range: 0-5V).

**Code**

.. note::
    You can **Modify/Reset/Copy/Run/Stop** the code below. But before that, you need to go to  source code path like ``raphael-kit/python``. After modifying the code, you can run it directly to see the effect.

.. raw:: html

    <run></run>

.. code-block:: python

    import RPi.GPIO as GPIO
    import ADC0834
    import time

    ledPins = [25, 12, 16, 20, 21, 5, 6, 13, 19, 26]

    def setup():
        GPIO.setmode(GPIO.BCM)
        ADC0834.setup()
        for i in ledPins:
            GPIO.setup(i, GPIO.OUT)
            GPIO.output(i, GPIO.HIGH)

    def LedBarGraph(value):
        for i in ledPins:
            GPIO.output(i,GPIO.HIGH)
        for i in range(value):
            GPIO.output(ledPins[i],GPIO.LOW)

    def destroy():
        GPIO.cleanup()

    def loop():
        while True:
            analogVal = ADC0834.getResult()
            LedBarGraph(int(analogVal/25))

    if __name__ == '__main__':
        setup()
        try:
            loop()
        except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the program destroy() will be executed.
            destroy()

**Code Explanation**

.. code-block:: python

    def LedBarGraph(value):
        for i in ledPins:
            GPIO.output(i,GPIO.HIGH)
        for i in range(value):
            GPIO.output(ledPins[i],GPIO.LOW)

This function works for controlling the turning on or off of the **10**
LEDs on the LED Bargraph. We give these **10** LEDs high levels to let
they are **off** at first, then decide how many LEDs are lit up by
changing the received analog value.

.. code-block:: python

    def loop():
        while True:
            analogVal = ADC0834.getResult()
            LedBarGraph(int(analogVal/25))

analogVal produces values (**0-255**) with varying voltage values
(**0-5V**), ex., if a 3V is detected on a battery, the corresponding
value **152** is displayed on the voltmeter.

The **10** LEDs on the LED Bargraph are used to display the
**analogVal** readings. 255/10=25, so every **25** the analog value
increases, one more LED turns on, ex., if “analogVal=150 (about 3V),
there are 6 LEDs turning on.”

Phenomenon Picture
------------------------------

.. image:: ../img/image249.jpeg
   :align: center