如何从DS18B20传感器获取温度并使用Arduino Yun将其显示在Adafruit LED背包（4x 7段）上

Question

我目前正在尝试（几个小时）在我的Adafruit LEDBackpack上显示从DS18B20获得的温度。但是，当我尝试在设置（ matrix.begin（0x070））中初始化显示时，传感器返回的温度始终 -127

你能帮我理解我做错了吗？

用例

1. 仅温度传感器：温度正确
2. 仅屏幕：屏幕按预期工作
3. 两者：屏幕工作并显示预期的返回温度始终为-127。

组件：

• Adafruit LEDBackpack正在使用I2C，因此它连接到SCL，SDA，5v，GND
• 温度传感器为DS18B20（1-Wire总线）。它连接到D＃2,5v，GND

代码

#include <OneWire.h>
#include <DallasTemperature.h>
#include <Bridge.h>
#include <Wire.h> // Enable this line if using Arduino Uno, Mega, etc.
#include "Adafruit_LEDBackpack.h"
#include "Adafruit_GFX.h"

#define ONE_WIRE_BUS 2
#define TEMP_DELAY 2000 // Request temp every two seconds

Adafruit_7segment matrix = Adafruit_7segment();

unsigned long time, lastTempCheck = 0;
float temp = 0;
OneWire oneWire(ONE_WIRE_BUS);

// Pass our oneWire reference to Dallas Temperature. 
DallasTemperature sensors(&oneWire);

void setup(void)
{
  // start serial port
  Serial.begin(9600);

  // Start up the library
  sensors.begin(); 
  matrix.begin(0x70); // If I comment this and do not use the matrix, the temperature is correct.
}

void loop(void)
{ 
  time = millis();

  if((time - lastTempCheck) > TEMP_DELAY){
    lastTempCheck = time;
    processTemp();
  }else { 
  matrix.print(100);
  matrix.writeDisplay();
  }
}

void processTemp(void){
  sensors.requestTemperatures(); // Send the command to get temperatures
  temp = sensors.getTempCByIndex(0);
  Serial.print("Temperature: ");
  Serial.println(temp);
}

模式

Answer 1

尝试为每个组件提供自己的电源（即LED - 3V和传感器 - 5v）。每个引脚只能输出足够的功率来阻止对电路板的损坏。 LED可能正在从传感器获取电力，传感器可能没有足够的电力来正常工作。

Answer 2

Your circuit diagram shows a short-circut over the (+) and (-) pins (legs) of the DS18B20 - that short horizontal wire below the resisitor. The value -127.0 indicates there is a problem with your temperature sensor too.

So if that's an actual problem (not just in the diagram), remove that wire to fix it. Also, in your setup(), you may want to add some kind of check that your sensors are A-OK before looping:

#include <OneWire.h>
#include <DallasTemperature.h>
#define ONE_WIRE_BUS    2  // Arduino pin D2
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

setup()
{
    Serial.begin(115200);
    Serial.println("setup() runs ...");

    sensors.begin();
    if (sensors.getDeviceCount() < 1)
    {
        Serial.println("DS18B20 Error - No sensors found");
    }
}

// ... rest of code