3.1.4 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 |
You can also buy them separately from the links below.
COMPONENT INTRODUCTION |
PURCHASE LINK |
|---|---|
- |
|
- |
|
- |
|
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/c/3.1.4/
Step 3: Compile.
gcc 3.1.4_SmartFan.c -lwiringPi -lm
Step 4: Run the executable file above.
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 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.
Note
If it does not work after running, or there is an error prompt: "wiringPi.h: No such file or directory", please refer to Install and Check the WiringPi.
Code¶
#include <wiringPi.h>
#include <stdio.h>
#include <softPwm.h>
#include <math.h>
typedef unsigned char uchar;
typedef unsigned int uint;
#define ADC_CS 0
#define ADC_CLK 1
#define ADC_DIO 2
#define MotorPin1 21
#define MotorPin2 22
#define MotorEnable 23
#define BtnPin 3
uchar get_ADC_Result(uint channel)
{
uchar i;
uchar dat1=0, dat2=0;
int sel = channel > 1 & 1;
int odd = channel & 1;
pinMode(ADC_DIO, OUTPUT);
digitalWrite(ADC_CS, 0);
// Start bit
digitalWrite(ADC_CLK,0);
digitalWrite(ADC_DIO,1); delayMicroseconds(2);
digitalWrite(ADC_CLK,1); delayMicroseconds(2);
//Single End mode
digitalWrite(ADC_CLK,0);
digitalWrite(ADC_DIO,1); delayMicroseconds(2);
digitalWrite(ADC_CLK,1); delayMicroseconds(2);
// ODD
digitalWrite(ADC_CLK,0);
digitalWrite(ADC_DIO,odd); delayMicroseconds(2);
digitalWrite(ADC_CLK,1); delayMicroseconds(2);
//Select
digitalWrite(ADC_CLK,0);
digitalWrite(ADC_DIO,sel); delayMicroseconds(2);
digitalWrite(ADC_CLK,1);
digitalWrite(ADC_DIO,1); delayMicroseconds(2);
digitalWrite(ADC_CLK,0);
digitalWrite(ADC_DIO,1); delayMicroseconds(2);
for(i=0;i<8;i++)
{
digitalWrite(ADC_CLK,1); delayMicroseconds(2);
digitalWrite(ADC_CLK,0); delayMicroseconds(2);
pinMode(ADC_DIO, INPUT);
dat1=dat1<<1 | digitalRead(ADC_DIO);
}
for(i=0;i<8;i++)
{
dat2 = dat2 | ((uchar)(digitalRead(ADC_DIO))<<i);
digitalWrite(ADC_CLK,1); delayMicroseconds(2);
digitalWrite(ADC_CLK,0); delayMicroseconds(2);
}
digitalWrite(ADC_CS,1);
pinMode(ADC_DIO, OUTPUT);
return(dat1==dat2) ? dat1 : 0;
}
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;
}
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;
}
void setup(){
if(wiringPiSetup() == -1){ //when initialize wiring failed,print messageto screen
printf("setup wiringPi failed !");
return;
}
softPwmCreate(MotorPin1, 0, 100);
softPwmCreate(MotorPin2, 0, 100);
pinMode(MotorEnable,OUTPUT);
pinMode(BtnPin,INPUT);
pinMode(ADC_CS, OUTPUT);
pinMode(ADC_CLK, OUTPUT);
}
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;
}
Code Explanation¶
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 2.2.2 Thermistor for more details.
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.
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:
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.