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4.1.10 Smart Fan

Introduction

In this project, we will use motors, buttons and thermistors to make a manual + automatic smart fan whose wind speed is adjustable.

Required Components

In this project, we need the following components.

../_images/list_Smart_Fan.png

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

Name

ITEMS IN THIS KIT

LINK

Raphael Kit

337

Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION

PURCHASE LINK

GPIO Extension Board

BUY

Breadboard

BUY

Jumper Wires

BUY

Resistor

BUY

Power Supply Module

-

Thermistor

BUY

L293D

-

ADC0834

-

Button

BUY

DC Motor

BUY

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

GPIO5

Pin 29

21

5

GPIO6

Pin 31

22

6

GPIO13

Pin 33

23

13

../_images/Schematic_three_one4.png

Experimental Procedures

Step 1: Build the circuit.

../_images/image245.png

Note

The power module can apply a 9V battery with the 9V Battery Buckle in the kit. Insert the jumper cap of the power module into the 5V bus strips of the breadboard.

../_images/image118.jpeg

Step 2: Get into the folder of the code.

cd ~/raphael-kit/python

Step 3: Run.

sudo python3 4.1.10_SmartFan.py

As the code runs, start the fan by pressing the button. Every time you press, 1 speed grade is adjusted up or down. There are 5 kinds of speed grades: 0~4. When set to the 4th speed grade and you press the button, the fan stops working with a 0 wind speed.

Once the temperature goes up or down for more than 2℃, the speed automatically gets 1-grade faster or slower.

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.

import RPi.GPIO as GPIO
import time
import ADC0834
import math

# Set up pins
MotorPin1   = 5
MotorPin2   = 6
MotorEnable = 13
BtnPin  = 22


def setup():
    global p_M1,p_M2
    ADC0834.setup()
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(MotorPin1, GPIO.OUT)
    GPIO.setup(MotorPin2, GPIO.OUT)
    p_M1=GPIO.PWM(MotorPin1,2000)
    p_M2=GPIO.PWM(MotorPin2,2000)
    p_M1.start(0)
    p_M2.start(0)
    GPIO.setup(MotorEnable, GPIO.OUT, initial=GPIO.LOW)
    GPIO.setup(BtnPin, GPIO.IN)

def temperature():
    analogVal = ADC0834.getResult()
    Vr = 5 * float(analogVal) / 255
    Rt = 10000 * Vr / (5 - Vr)
    temp = 1/(((math.log(Rt / 10000)) / 3950) + (1 / (273.15+25)))
    Cel = temp - 273.15
    Fah = Cel * 1.8 + 32
    return Cel

def motor(level):
    if level == 0:
        GPIO.output(MotorEnable, GPIO.LOW)
        return 0
    if level>=4:
        level = 4
    GPIO.output(MotorEnable, GPIO.HIGH)
    p_M1.ChangeDutyCycle(level*25)
    return level


def main():
    lastState=0
    level=0
    markTemp = temperature()
    while True:
        currentState =GPIO.input(BtnPin)
        currentTemp=temperature()
        if currentState == 1 and lastState == 0:
            level=(level+1)%5
            markTemp = currentTemp
            time.sleep(0.5)
        lastState=currentState
        if level!=0:
            if currentTemp-markTemp <= -2:
                level = level -1
                markTemp=currentTemp
            if currentTemp-markTemp >= 2:
                level = level +1
                markTemp=currentTemp
        level = motor(level)


def destroy():
    GPIO.output(MotorEnable, GPIO.LOW)
    p_M1.stop()
    p_M2.stop()
    GPIO.cleanup()

if __name__ == '__main__':
    setup()
    try:
        main()
    except KeyboardInterrupt:
        destroy()

Code Explanation

def temperature():
    analogVal = ADC0834.getResult()
    Vr = 5 * float(analogVal) / 255
    Rt = 10000 * Vr / (5 - Vr)
    temp = 1/(((math.log(Rt / 10000)) / 3950) + (1 / (273.15+25)))
    Cel = temp - 273.15
    Fah = Cel * 1.8 + 32
    return Cel

temperture() works by converting thermistor values read by ADC0834 into temperature values. Refer to 2.2.2 Thermistor for more details.

def motor(level):
    if level == 0:
        GPIO.output(MotorEnable, GPIO.LOW)
        return 0
    if level>=4:
        level = 4
    GPIO.output(MotorEnable, GPIO.HIGH)
    p_M1.ChangeDutyCycle(level*25)
    return level

This function controls the rotating speed of the motor. The range of the Lever: 0-4 (level 0 stops the working motor). One level adjustment stands for a 25% change of the wind speed.

def main():
    lastState=0
    level=0
    markTemp = temperature()
    while True:
        currentState =GPIO.input(BtnPin)
        currentTemp=temperature()
        if currentState == 1 and lastState == 0:
            level=(level+1)%5
            markTemp = currentTemp
            time.sleep(0.5)
        lastState=currentState
        if level!=0:
            if currentTemp-markTemp <= -2:
                level = level -1
                markTemp=currentTemp
            if currentTemp-markTemp >= 2:
                level = level +1
                markTemp=currentTemp
        level = motor(level)

The function main() contains the whole program process as shown:

  1. Constantly read the button state and the current temperature.

  2. Every press makes level+1 and at the same time, the temperature is updated. The Level ranges 1~4.

  3. As the fan works ( the level is not 0), the temperature is under detection. A 2℃+ change causes the up and down of the level.

  4. The motor changes the rotating speed with the Level.

Phenomenon Picture

../_images/image246.png