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3.1.4 Smart Fan
=================
Introduction
-----------------
In this course, we will use motors, buttons and thermistors to make a
manual + automatic smart fan whose wind speed is adjustable.
Components
------------------
.. image:: img/list_Smart_Fan.png
:align: center
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
============ ======== ======== ===
.. image:: img/Schematic_three_one4.png
:width: 500
:align: center
Experimental Procedures
-----------------------------
**Step 1:** Build the circuit.
.. image:: img/image245.png
:width: 800
:align: center
.. 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.
.. image:: img/image118.jpeg
:width: 2.80694in
:height: 0.94375in
:align: center
**For C Language Users**
^^^^^^^^^^^^^^^^^^^^^^^^^
**Step 2**: Get into the folder of the code.
.. raw:: html
.. code-block::
cd ~/davinci-kit-for-raspberry-pi/c/3.1.4/
**Step 3**: Compile.
.. raw:: html
.. code-block::
gcc 3.1.4_SmartFan.c -lwiringPi -lm
**Step 4**: Run the executable file above.
.. raw:: html
.. code-block::
sudo ./a.out
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\ :sup:`th` speed grade and you
press the button, the fan stops working with a **0** wind speed.
.. 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:`C code is not working?`.
Once the temperature goes up or down for more than 2℃, the speed
automatically gets 1-grade faster or slower.
**Code Explanation**
.. code-block:: c
int temperture(){
unsigned char analogVal;
double Vr, Rt, temp, cel, Fah;
analogVal = get_ADC_Result(0);
Vr = 5 * (double)(analogVal) / 255;
Rt = 10000 * (double)(Vr) / (5 - (double)(Vr));
temp = 1 / (((log(Rt/10000)) / 3950)+(1 / (273.15 + 25)));
cel = temp - 273.15;
Fah = cel * 1.8 +32;
int t=cel;
return t;
}
Temperture() works by converting thermistor values read by ADC0834 into
temperature values. Refer to :ref:`2.2.2 Thermistor` for more details.
.. code-block:: c
int motor(int level){
if(level==0){
digitalWrite(MotorEnable,LOW);
return 0;
}
if (level>=4){
level =4;
}
digitalWrite(MotorEnable,HIGH);
softPwmWrite(MotorPin1, level*25);
return level;
}
This function controls the rotating speed of the motor. The range of the
**Level**: **0-4** (level **0** stops the working motor). One level
adjustment stands for a **25%** change of the wind speed.
.. code-block:: c
int main(void)
{
setup();
int currentState,lastState=0;
int level = 0;
int currentTemp,markTemp=0;
while(1){
currentState=digitalRead(BtnPin);
currentTemp=temperture();
if (currentTemp<=0){continue;}
if (currentState==1&&lastState==0){
level=(level+1)%5;
markTemp=currentTemp;
delay(500);
}
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);
}
return 0;
}
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**.
**For Python Language Users**
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
**Step 2**: Get into the folder of the code.
.. raw:: html
.. code-block::
cd ~/davinci-kit-for-raspberry-pi/python
**Step 3**: Run.
.. raw:: html
.. code-block::
sudo python3 3.1.4_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\ :sup:`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 ``davinci-kit-for-raspberry-pi/python``.
.. raw:: html
.. code-block:: python
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**
.. code-block:: python
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 :ref:`2.2.2 Thermistor` for more details.
.. code-block:: python
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.
.. code-block:: python
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
------------------------
.. image:: img/image246.png
:align: center