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.. _2.2.7_py:
2.2.7 PIR
=========
Introduction
------------
In this project, we will make a device by using the human body infrared
pyroelectric sensors. When someone gets closer to the LED, the LED will
turn on automatically. If not, the light will turn off. This infrared
motion sensor is a kind of sensor that can detect the infrared emitted
by human and animals.
Required Components
------------------------------
In this project, we need the following components.
.. image:: ../img/list_2.2.4_pir2.png
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_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_rgb_led`
- |link_rgb_led_buy|
* - :ref:`cpn_pir`
- \-
Schematic Diagram
-----------------
.. image:: ../img/image327.png
Experimental Procedures
-----------------------
**Step 1:** Build the circuit.
.. image:: ../img/image214.png
**Step 2:** Go to the folder of the code.
.. raw:: html
.. code-block::
cd ~/raphael-kit/python/
**Step 3:** Run the executable file.
.. raw:: html
.. code-block::
sudo python3 2.2.7_PIR.py
After the code runs, PIR detects surroundings and let RGB LED glow yellow if it senses someone walking 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.
.. image:: ../img/PIR_TTE.png
:width: 400
:align: center
**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
.. code-block:: python
import RPi.GPIO as GPIO
import time
rgbPins = {'Red':18, 'Green':27, 'Blue':22}
pirPin = 17 # the pir connect to pin17
def setup():
global p_R, p_G, p_B
GPIO.setmode(GPIO.BCM) # Set the GPIO modes to BCM Numbering
GPIO.setup(pirPin, GPIO.IN) # Set pirPin to input
# Set all LedPin's mode to output and initial level to High(3.3v)
for i in rgbPins:
GPIO.setup(rgbPins[i], GPIO.OUT, initial=GPIO.HIGH)
# Set all led as pwm channel and frequece to 2KHz
p_R = GPIO.PWM(rgbPins['Red'], 2000)
p_G = GPIO.PWM(rgbPins['Green'], 2000)
p_B = GPIO.PWM(rgbPins['Blue'], 2000)
# Set all begin with value 0
p_R.start(0)
p_G.start(0)
p_B.start(0)
# Define a MAP function for mapping values. Like from 0~255 to 0~100
def MAP(x, in_min, in_max, out_min, out_max):
return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min
# Define a function to set up colors
def setColor(color):
# configures the three LEDs' luminance with the inputted color value .
# Devide colors from 'color' veriable
R_val = (color & 0xFF0000) >> 16
G_val = (color & 0x00FF00) >> 8
B_val = (color & 0x0000FF) >> 0
# Map color value from 0~255 to 0~100
R_val = MAP(R_val, 0, 255, 0, 100)
G_val = MAP(G_val, 0, 255, 0, 100)
B_val = MAP(B_val, 0, 255, 0, 100)
#Assign the mapped duty cycle value to the corresponding PWM channel to change the luminance.
p_R.ChangeDutyCycle(R_val)
p_G.ChangeDutyCycle(G_val)
p_B.ChangeDutyCycle(B_val)
#print ("color_msg: R_val = %s, G_val = %s, B_val = %s"%(R_val, G_val, B_val))
def loop():
while True:
pir_val = GPIO.input(pirPin)
if pir_val==GPIO.HIGH:
setColor(0xFFFF00)
else :
setColor(0x0000FF)
def destroy():
p_R.stop()
p_G.stop()
p_B.stop()
GPIO.cleanup() # Release resource
if __name__ == '__main__': # Program start from here
setup()
try:
loop()
except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the child program destroy() will be executed.
destroy()
**Code Explanation**
.. code-block:: python
rgbPins = {'Red':18, 'Green':27, 'Blue':22}
def setup():
global p_R, p_G, p_B
GPIO.setmode(GPIO.BCM)
# ……
for i in rgbPins:
GPIO.setup(rgbPins[i], GPIO.OUT, initial=GPIO.HIGH)
p_R = GPIO.PWM(rgbPins['Red'], 2000)
p_G = GPIO.PWM(rgbPins['Green'], 2000)
p_B = GPIO.PWM(rgbPins['Blue'], 2000)
p_R.start(0)
p_G.start(0)
p_B.start(0)
def MAP(x, in_min, in_max, out_min, out_max):
return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min
def setColor(color):
...
These codes are used to set the color of the RGB LED, and please refer
to :ref:`1.1.2_py` for more details.
.. code-block:: python
def loop():
while True:
pir_val = GPIO.input(pirPin)
if pir_val==GPIO.HIGH:
setColor(0xFFFF00)
else :
setColor(0x0000FF)
When PIR detects the human infrared spectrum, RGB LED emits the yellow
light; if not, emits the blue light.
Phenomenon Picture
------------------
.. image:: ../img/image215.jpeg