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.. _1.1.3_c:

1.1.3 LED Bar Graph
=========================

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

In this project, we sequentially illuminate the lights on the LED Bar
Graph.

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

In this project, we need the following components. 

.. image:: ../img/list_led_bar.png

.. 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`
        - \-

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

============ ======== ======== ===
T-Board Name physical wiringPi BCM
GPIO17       Pin 11   0        17
GPIO18       Pin 12   1        18
GPIO27       Pin 13   2        27
GPIO22       Pin 15   3        22
GPIO23       Pin 16   4        23
GPIO24       Pin 18   5        24
GPIO25       Pin 22   6        25
SDA1         Pin 3    8        2
SCL1         Pin 5    9        3
SPICE0       Pin 24   10       8
============ ======== ======== ===

.. image:: ../img/schematic_led_bar.png


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

**Step 1**: Build the circuit.

.. note::

    Pay attention to the direction when connecting. If you connect it backwards, it will not light up.

.. image:: ../img/image66.png


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

.. raw:: html

   <run></run>

.. code-block::

    cd ~/raphael-kit/c/1.1.3/

**Step 3**: Compile the code.

.. raw:: html

   <run></run>

.. code-block::

    gcc 1.1.3_LedBarGraph.c -lwiringPi

**Step 4:** Run the executable file.

.. raw:: html

   <run></run>

.. code-block::

    sudo ./a.out

After the code runs, you will see the LEDs on the LED bar turn on and off regularly.

.. note::

   If it does not work after running, or there is an error prompt: \"wiringPi.h: No such file or directory\", please refer to :ref:`install_wiringpi`.



**Code**

.. code-block:: c

    #include <wiringPi.h>
    #include <stdio.h>

    int pins[10] = {0,1,2,3,4,5,6,8,9,10};
    void oddLedBarGraph(void){
        for(int i=0;i<5;i++){
            int j=i*2;
            digitalWrite(pins[j],HIGH);
            delay(300);
            digitalWrite(pins[j],LOW);
        }
    }
    void evenLedBarGraph(void){
        for(int i=0;i<5;i++){
            int j=i*2+1;
            digitalWrite(pins[j],HIGH);
            delay(300);
            digitalWrite(pins[j],LOW);
        }
    }
    void allLedBarGraph(void){
        for(int i=0;i<10;i++){
            digitalWrite(pins[i],HIGH);
            delay(300);
            digitalWrite(pins[i],LOW);
        }
    }
    int main(void)
    {
        if(wiringPiSetup() == -1){ //when initialize wiring failed,print message to screen
            printf("setup wiringPi failed !");
            return 1;
        }
        for(int i=0;i<10;i++){       //make led pins' mode is output
            pinMode(pins[i], OUTPUT);
            digitalWrite(pins[i],LOW);
        }
        while(1){
            oddLedBarGraph();
            delay(300);
            evenLedBarGraph();
            delay(300);
            allLedBarGraph();
            delay(300);
        }
        return 0;
    }

**Code Explanation**

.. code-block:: c

    int pins[10] = {0,1,2,3,4,5,6,8,9,10};

Create an array and assign it to the pin number corresponding to the LED
Bar Graph (0,1,2,3,4,5,6,8,9,10) and the array will be used to control
the LED.

.. code-block:: c

    void oddLedBarGraph(void){
        for(int i=0;i<5;i++){
            int j=i*2;
            digitalWrite(pins[j],HIGH);
            delay(300);
            digitalWrite(pins[j],LOW);
        }
    }

Let the LED on the odd digit of the LED Bar Graph light on in turn.

.. code-block:: c

    void evenLedBarGraph(void){
        for(int i=0;i<5;i++){
            int j=i*2+1;
            digitalWrite(pins[j],HIGH);
            delay(300);
            digitalWrite(pins[j],LOW);
        }
    }

Make the LED on the even digit of the LED Bar Graph light on in turn.

.. code-block:: c

    void allLedBarGraph(void){
        for(int i=0;i<10;i++){
            digitalWrite(pins[i],HIGH);
            delay(300);
            digitalWrite(pins[i],LOW);
        }
    }

Let the LED on the LED Bar Graph light on one by one.

**Phenomenon Picture**

.. image:: ../img/image67.jpeg