问题描述
对于大学中的一个项目,我必须测量各种水质,包括温度。温度传感器是DS18B20,我使用Arduino Mega板进行了整个展示。与DS18B20一起运行的个人只能返回任何有意义的数字。而不是25C(或类似的温度),它返回-127。
下面的代码来自达拉斯温度(变化很小,例如有延迟和删除一些注释行)
// Include the libraries we need
#include <OneWire.h>
#include <Dallastemperature.h>
// Data wire is plugged into port 2 on the Arduino
#define ONE_WIRE_BUS 48
// Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
OneWire oneWire(ONE_WIRE_BUS);
// Pass our oneWire reference to Dallas Temperature.
Dallastemperature sensors(&oneWire);
void setup(void)
{
// start serial port
Serial.begin(9600);
Serial.println("Dallas Temperature IC Control Library Demo");
// Start up the library
sensors.begin();
}
void loop(void)
{
delay(500);
sensors.requestTemperatures(); // Send the command to get temperatures
Serial.println("DONE");
Serial.print("Temperature for the device 1 (index 0) is: ");
Serial.println(sensors.getTempCByIndex(0));
delay(2500);
}
这实际上是来自Wiki page of DFRobot(我的传感器的来源)
#include <OneWire.h>
int DS18S20_Pin = 48; //DS18S20 Signal pin on digital 48
//Temperature chip I/O
OneWire ds(DS18S20_Pin); // on digital pin 48
void setup(void) {
Serial.begin(9600);
}
void loop(void) {
float temperature = getTemp();
Serial.println(temperature);
delay(100); //just here to slow down the output so it is easier to read
}
float getTemp(){
//returns the temperature from one DS18S20 in DEG Celsius
byte data[12];
byte addr[8];
if ( !ds.search(addr)) {
//no more sensors on chain,reset search
ds.reset_search();
return -1000;
}
if ( OneWire::crc8( addr,7) != addr[7]) {
Serial.println("CRC is not valid!");
return -1000;
}
if ( addr[0] != 0x10 && addr[0] != 0x28) {
Serial.print("Device is not recognized");
return -1000;
}
ds.reset();
ds.select(addr);
ds.write(0x44,1); // start conversion,with parasite power on at the end
byte present = ds.reset();
ds.select(addr);
ds.write(0xBE); // Read Scratchpad
for (int i = 0; i < 9; i++ ) { // we need 9 bytes
data[i] = ds.read();
}
ds.reset_search();
byte MSB = data[1];
byte LSB = data[0];
float tempRead = ((MSB << 8) | LSB); //using two's compliment
float TemperatureSum = tempRead / 16;
return TemperatureSum;
}
此特定代码每次都会返回-1000,我认为是与上面的-127等价。
解决方法
来自图书馆:
// Error Codes
#define DEVICE_DISCONNECTED_C -127
因此您的设备未连接/未通信。检查您的接线和引脚号。