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.

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

Experimental Procedures¶

Step 1: Build the circuit.

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.

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 4^th 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:

Constantly read the button state and the current temperature.
Every press makes level+1 and at the same time, the temperature is updated. The Level ranges 1~4.
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.
The motor changes the rotating speed with the Level.