Question

我需要使用AVR ATMEGA88开发一个简单的温度计。我正在使用我发现的库来读取热电偶的温度（用max6675键入k）。我可以使用函数gettemp（）正确读取温度，但是当我在结果值上使用运算符时，它返回0。

因为函数返回0.25摄氏度的值，我需要除以4，我还需要将值分成两部分以显示在七段显示器上。

我的代码：

#include <avr/io.h>
#include <util/delay.h>
#include "max6675.h"

/*
Max6675 library by Tobias Schlegel, 5.2009
www.tobias-schlegel.de

Report bugs to tobias@drschlegel.de

This software is deliveres as-is and comes with absolute NO warranty.
This software is published under GNU license.
*/

uint16_t gettemp(void);                          //Functie declaratie
void initavr(void);

// Geeft temperatuur per 0.25 graden celsius.
uint16_t gettemp(void) {                          //Haal de temperatuur op
  uint8_t bit = 0, bitnr = 12;                    //Variabelen
  uint8_t foo1 = 0;
  uint16_t Rohdata = 0;
  CS_Port &= ~(1 << CS);                        //Chip select anlegen
  for (foo1 = 0; foo1 < 16; foo1++) {                  //16 Bits Uitlezen
    bit = 15 - foo1;                        //Die Aktuelle Bitnr berechnen.
    SCK_Port |= (1 << SCK);                      //SCK hi
    if ((bit <= 14) && (bit >= 3)) {                  //Einfach mal die 12 relevanten von den 16 Bits ausfiltern
      if ((SO_Pin & (1 << SO))) {                    //WENN SO 1 ist, dann...
        bitnr--;                        //z�hlen wir runter...
        Rohdata |= (1 << bitnr);                // und schieben eine 1 an bit x
      } else {                            //WENN dem NICHT so ist, dann...
        bitnr--;                        //z�hlen wir runter...
        Rohdata &= ~(1 << bitnr);                //und schieben eine 0 an bit x
      }
    } else {                              //weis au nimmer, was das soll.
      bitnr = 12;
    }
    SCK_Port &= ~(1 << SCK);                    //SCK LO
  }
  CS_Port |= (1 << CS);                        //CS HI  //Alles auf Standardkonfig.
  return Rohdata;                            //Geeft de temperatuur terug
}


// getTC() returns 0 if Thermocouple is not connected, 255 if thermocouple is connected
// (to enable this feature T- must be connected to GND)
uint8_t getTC(void) {
  uint8_t TC = 0;
  uint8_t foo1 = 0;

  CS_Port &= ~(1 << CS);                        //Chip select anlegen
  for (foo1 = 0; foo1 < 16; foo1++) {                  //16 Bits einlesen                                               //Die Aktuelle Bitnr berechnen.
    SCK_Port |= (1 << SCK);                      //SCK hi

    if (foo1 == 2) {                          //das 3. bit ist f�r uns relevant.
      if ((SO_Pin & (1 << SO))) {         //Geeft 0 wanneer er geen thermocouple gedeteceerd wordt
        TC = 0;
      } else {                            //Geeft 255 wanneer er een thermocouple gedeteceerd wordt
        TC = 255;
      }
    }
    SCK_Port &= ~(1 << SCK);                    //SCK LO
  }
  CS_Port |= (1 << CS);                        //CS HI
  return TC;                              //Geeft 0 of 255 afhankelijk of thermocouple is gedetecteerd
}

//Initialiseert de MAX6675 en de IO-pins
void init_6675(void) {                          //AVR initialiseren
  SO_DDR &= ~(1 << SO);
  CS_DDR |= (1 << CS);
  SCK_DDR |= (1 << SCK);                        //IOs instellen
  SO_Port |= (1 << SO);                          //Pullups aan. (Belangrijk voor de MAX6675)
  CS_Port |= (1 << CS);                        //CS HI  Poort afkomstig uit de configuratie
  SCK_Port &= ~(1 << SCK);                      //SCK LO
}

void updateTemp(void) {
  const uint16_t numbers[10] = {0b11000000, 0b11111001, 0b10010010, 0b10110000, 0b10101001, 0b10100100, 0b10000100, 0b11110001, 0b10000000, 0b10100000}; //Numbers on 7Segment

  uint16_t temperature =  gettemp() / 4; //Get temperature and divide by 4 to get degrees celcius

  //Split number to display on 7segment
  uint16_t single = temperature % 10;
  uint16_t decimal = (temperature - single) / 10;

//    uint16_t test = 344 / 4; //Test value - this display correctly on 7segment
//    uint16_t single = test % 10;
//    uint16_t decimal = (test - single) / 10;

  for (int i = 0; i < 1000; i++){
    PORTB = 0b00000010;
    PORTD = numbers[single];
    _delay_ms(1);
    PORTB = 0b00000100;
    PORTD = numbers[decimal];
    _delay_ms(1);
  }
}

int main(void) {
  DDRD |= 0b11111111; //Alle D poorten op output
  DDRC |= 0b00011111; //
  DDRB |= 0b11001110; //

  init_6675(); //Initialiseer de MAX6675

  while (1) {

    uint8_t isThereATC =  getTC();

    if (isThereATC == 0) {
      PORTB = 0b01000000; //No Thermocouple
      PORTD = 0b11111111;
    }
    else if (isThereATC == 255) {
      updateTemp();
    }
    else {
      PORTD = 0b11111111; //Error
    }
    _delay_ms(2000);
  }
  return 0;
}

我知道我的热电偶有效，因为如果我不使用操作器并使用LED来显示温度范围是正常的。

编辑：问题出现在以下功能中。我使用temperature = gettemp() / 4来获取温度。这会返回0。

 void updateTemp(void) {
      const uint16_t numbers[10] = {0b11000000, 0b11111001, 0b10010010, 0b10110000, 0b10101001, 0b10100100, 0b10000100, 0b11110001, 0b10000000, 0b10100000}; //Numbers on 7Segment

      uint16_t temperature =  gettemp() / 4; //Get temperature and divide by 4 to get degrees celcius

      //Split number to display on 7segment
      uint16_t single = temperature % 10;
      uint16_t decimal = (temperature - single) / 10;

    //    uint16_t test = 344 / 4; //Test value - this display correctly on 7segment
    //    uint16_t single = test % 10;
    //    uint16_t decimal = (test - single) / 10;

      for (int i = 0; i < 1000; i++){ //Display on 7Segment
        PORTB = 0b00000010;
        PORTD = numbers[single]; //Number right
        _delay_ms(1);
        PORTB = 0b00000100;
        PORTD = numbers[decimal]; //Number left
        _delay_ms(1);
      }
    }

EDIT2：我将除数除以4，并使用以下代码确定temperature

的值

       if (temperature == 0){
            PORTB = 0b10000000; //Green LED
            PORTD = 0b11111111;
          }
else if (temperature > 0 && temperature < 100) {
PORTB = 0b00000100; //Blue LED
            PORTD = 0b11111111;
}
          else {
            PORTB = 0b00001000; //Red LED
            PORTD = 0b11111111;
          }

希望你能帮助我。

使用运算符

0 个答案: