Question

我被分配了一项任务，即创建一个控制PWM输出的基于温度的风扇。我正在使用Arduino Uno与AVRISPmkII程序员和ATmega328控制器。现在的任务是在MLX90614线上连接4 I²C个传感器（我已经为每个传感器分配了不同的从地址，因为我无法在I²C上连接它们，每个传感器具有相同的地址）。

我能够读取每个传感器的温度并获得最高温度。但是当通过PWM控制四个风扇时会出现问题。我必须从每个传感器获取温度读数，获得最高温度，然后根据PWM输出的设定温度范围控制风扇的速度。代码有什么问题？

#include <i2cmaster.h>

int PWMoutput=0;
int Temp[4];
int sensor[4]={0xAC<<1, 0xCC<<1, 0xC0<<1, 0xB0<<1};  // Array with address of four mlx90614 sensors
int Maxtemp;

int fan = 9;      // FAN connected to digital pin 9

//------------------------------------------------//
//------------------SETUP-------------------------//
//------------------------------------------------//

void setup()
{
    Serial.begin(9600);                       // Start serial communication at 9600 bit/s.
    i2c_init();                               // Initialise the I²C bus.
    PORTC = (1 << PORTC4) | (1 << PORTC5);    // Enable pullups.

    // Initialize the digital pin as an output.
    pinMode(fan, OUTPUT);
}

//------------------------------------------------//
//-------------------MAIN-------------------------//
//------------------------------------------------//

void loop()
{
    Maxtemp=readtemp(0);
    setfanmode(Maxtemp);
                      // Prints all readings in the serial port
    i=0;

    /*while(i<1)
    {
        Serial.print("Sensor");
        Serial.println(i,DEC);
        Serial.print("Celcius: ");
        Serial.println(Temp[i],DEC);
        i++;

    }*/

    Serial.print("Maximum: Celcius: ");
    Serial.println(Maxtemp);
}

void setfanmode(int degree)  // Setting the fan speed modes according to
                             // the temperature in Celcius
                             // with PWM Duty cycle to 0%, 50% and 100%.
{
    if (degree<=30)
        PWMoutput=0;
    else if(degree<=60)
        PWMoutput=127;
    else if(degree<=80)
        PWMoutput=255;
}

int maxtemp()             // Reading max temperature
{
    int i=1;
    int temperature;
    while (i<4)
    {
        if (Temp[i-1]<Temp[i])
            temperature=Temp[i];
        i++;
    }
    return(temperature);
}

float readtemp(int sensornumb)
{
    int data_low = 0;
    int data_high = 0;
    int pec = 0;

    // Write
    i2c_start_wait(sensor[sensornumb]+I2C_WRITE);
    i2c_write(0x07);

    // Read
    i2c_rep_start(sensor[sensornumb]+I2C_READ);
    data_low = i2c_readAck();       // Read 1 byte and then send ack.
    data_high = i2c_readAck();      // Read 1 byte and then send ack.
    pec = i2c_readNak();
    i2c_stop();

    // This converts high and low bytes together and processes temperature,
    // MSB is a error bit and is ignored for temperatures.
    double tempFactor = 0.02;       // 0.02 degrees per LSB (measurement
                                    // resolution of the MLX90614).
    double tempData = 0x0000;       // Zero out the data.
    int frac;                       // Data past the decimal point.

    // This masks off the error bit of the high byte, then moves it left
    // 8 bits and adds the low byte.
    tempData = (double)(((data_high & 0x007F) << 8) + data_low);
    tempData = (tempData * tempFactor)-0.01;
    float celcius = tempData - 273.15;

    // Returns temperature in Celcius.
    return celcius;
}

Answer 1

我没有阅读你的所有代码，但看起来你根本就没有指挥你的粉丝。

/* setting the fan speed modes according to
 * the temperature in celcius
 * with PWM Duty cycle to 0%, 50% & 100%
 */
void setfanmode(int degree)   
{
  int PWMoutput;

  if (degree<=30)
    PWMoutput=0;
  else if(degree<=60)
    PWMoutput=127;    
  else if(degree<=80)
    PWMoutput=255;
  analogWrite(fan, PWMoutput);
}

会让你的'setfanmode'功能做点什么。但是，我没有检查其余代码中的错误。如果您要控制多个风扇，您可能需要将功能更改为以下内容：

void setfanmode(int degree, int fanpin)
{
  int PWMoutput;

  if (degree<=30)
    PWMoutput=0;
  else if(degree<=60)
    PWMoutput=127;    
  else if(degree<=80)
    PWMoutput=255;
  analogWrite(fanpin, PWMoutput);
}

我想让你想象如何转换你的代码以控制几个粉丝。

Arduino Uno代码上有多个MLX90614（温度传感器）

1 个答案: