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3.1.2 Welcome
===============

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

In this project, we will use PIR to sense the movement of pedestrians,
and use servos, LED, buzzer to simulate the work of the sensor door of
the convenience store. When the pedestrian appears within the sensing
range of the PIR, the indicator light will be on, the door will be
opened, and the buzzer will play the opening bell.

Components
---------------

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

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

============ ======== ======== ===
T-Board Name physical wiringPi BCM
GPIO18       Pin 12   1        18
GPIO17       Pin 11   0        17
GPIO27       Pin 13   2        27
GPIO22       Pin 15   3        22
============ ======== ======== ===

.. image:: img/Schematic_three_one2.png
   :align: center

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

**Step 1:** Build the circuit.

.. image:: img/image239.png
    :width: 800
    :align: center


**Step 2:** Change directory.

.. raw:: html

   <run></run>

.. code-block:: 

    cd ~/davinci-kit-for-raspberry-pi/c/3.1.2/

**Step 3:** Compile.

.. raw:: html

   <run></run>

.. code-block:: 

    gcc 3.1.2_Welcome.c -lwiringPi

**Step 4:** Run.

.. raw:: html

   <run></run>

.. code-block:: 

    sudo ./a.out

After the code runs, if the PIR sensor detects someone passing by, the
door will automatically open (simulated by the servo), turn on the
indicator and play the doorbell music. After the doorbell music plays,
the system will automatically close the door and turn off the indicator
light, waiting for the next time someone passes by.

There are two potentiometers on
the PIR module: one is to adjust sensitivity and the other is to adjust
the detection distance. To make the PIR module work better, you
You need to turn both of them counterclockwise to the end.

.. 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_pi5`.

**Code Explanation**

.. code-block:: c

    void setAngle(int pin, int angle){    //Create a funtion to control the angle of the servo.
        if(angle < 0)
            angle = 0;
        if(angle > 180)
            angle = 180;
        softPwmWrite(pin,Map(angle, 0, 180, 5, 25));   
    } 

Create a function, setAngle to write the angle in the servo that is
0-180.

.. code-block:: c

    void doorbell(){
    for(int i=0;i<sizeof(song)/4;i++){
            softToneWrite(BuzPin, song[i]); 
            delay(beat[i] * 250);
        }

Create a function, doorbell to enable the buzzer to play music.

.. code-block:: c

    void closedoor(){
    digitalWrite(ledPin, LOW);   //led off
    for(int i=180;i>-1;i--){  //make servo rotate from maximum angle to minimum angle
        setAngle(servoPin,i);
        delay(1);
        }
    }

Create a closedoor function to simulate closing the door, turn off the
LED and let the servo turn from 180 degrees to 0 degree.

.. code-block:: c

    void opendoor(){
        digitalWrite(ledPin, HIGH);   //led on
        for(int i=0;i<181;i++){  //make servo rotate from minimum angle to maximum angle
            setAngle(servoPin,i);
            delay(1);
        }
        doorbell();
        closedoor();
    }

The function opendoor() includes several parts: turn on the indicator
light, turn the servo (simulate the action of opening the door), play
the doorbell music of the convenience store, and call the function
closedoor() after playing music.

.. code-block:: c

        int main(void)
    {
        if(wiringPiSetup() == -1){ //when initialize wiring failed,print message to screen
            printf("setup wiringPi failed !");
            return 1;
        }
        if(softToneCreate(BuzPin) == -1){
            printf("setup softTone failed !");
            return 1;
    ......

In the function main(), initialize library wiringPi and setup softTone,
then set ledPin to output state and pirPin to input state. If the PIR
sensor detects someone passing by, the function opendoor will be called
to simulate opening the door.