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[on:]

Hi everyone,
This is my first post here, I am very new to Arduino so please forgive me if I have left out any important info that will help you help me.

I have been working on a project using two ds18b20 temperature sensors.  Without going into detail (unless you want to know )   I am using the sensors to turn on servos.   I have mashed together various bits of code I have found and feel like I’m making real progress which has been very exciting.

I have been using the Miles Burton - Dallas temperature control library.  In particular the alarm handler and multiple sketches.    Two  ds18b20 sensors in parasitic mode.

So far I have figured out I can turn on servos using the alarm feature but what I would like to do is to be able to compare the results of the two sensors.     for example: if sensor A is equal to sensor B...

I can manipulate the code to effect both the sensors but can’t figure out how to address each sensor individually.   Can you point me in the right direction?

 Cheers
Jim

[Reply #1 on:]

Start with posting your code ...

[Reply #2 on:]

 The code I started with was the alarmhandler.pde  (Miles Burton )  I have pasted it below.   I used the straight Burton code without my additions as they don't relate to this  (I'm sure my additions will feature in another post asking for help soon   )

thanks

#include <OneWire.h>
#include <DallasTemperature.h>

// Data wire is plugged into port 2 on the Arduino
#define ONE_WIRE_BUS 2

// 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);

// arrays to hold device addresses
DeviceAddress insideThermometer, outsideThermometer;

// function that will be called when an alarm condition exists during DallasTemperatures::processAlarms();
void newAlarmHandler(uint8_t* deviceAddress)
{
  Serial.println("Alarm Handler Start");
  printAlarmInfo(deviceAddress);
  printTemp(deviceAddress);
  Serial.println();
  Serial.println("Alarm Handler Finish");
}

void printCurrentTemp(DeviceAddress deviceAddress)
{
  printAddress(deviceAddress);
  printTemp(deviceAddress);
  Serial.println();
}

void printAddress(DeviceAddress deviceAddress)
{
  Serial.print("Address: ");
  for (uint8_t i = 0; i < 8; i++)
  {
    if (deviceAddress < 16) Serial.print("0");
    Serial.print(deviceAddress, HEX);
  }
  Serial.print(" ");
}

void printTemp(DeviceAddress deviceAddress)
{
  float tempC = sensors.getTempC(deviceAddress);
  if (tempC != DEVICE_DISCONNECTED)
  {
    Serial.print("Current Temp C: ");
    Serial.print(tempC);
  }
  else Serial.print("DEVICE DISCONNECTED");
  Serial.print(" ");
}

void printAlarmInfo(DeviceAddress deviceAddress)
{
  char temp;
  printAddress(deviceAddress);
  temp = sensors.getHighAlarmTemp(deviceAddress);
  Serial.print("High Alarm: ");
  Serial.print(temp, DEC);
  Serial.print("C");
  Serial.print(" Low Alarm: ");
  temp = sensors.getLowAlarmTemp(deviceAddress);
  Serial.print(temp, DEC);
  Serial.print("C");
  Serial.print(" ");
}

void setup(void)
{
  // start serial port
  Serial.begin(9600);
  Serial.println("Dallas Temperature IC Control Library Demo");

  // Start up the library
  sensors.begin();
  
  // locate devices on the bus
  Serial.print("Found ");
  Serial.print(sensors.getDeviceCount(), DEC);
  Serial.println(" devices.");

  // search for devices on the bus and assign based on an index
  if (!sensors.getAddress(insideThermometer, 0)) Serial.println("Unable to find address for Device 0");
  if (!sensors.getAddress(outsideThermometer, 1)) Serial.println("Unable to find address for Device 1");

  Serial.print("Device insideThermometer ");
  printAlarmInfo(insideThermometer);
  Serial.println();
  
  Serial.print("Device outsideThermometer ");
  printAlarmInfo(outsideThermometer);
  Serial.println();
  
  // set alarm ranges
  Serial.println("Setting alarm temps...");
  sensors.setHighAlarmTemp(insideThermometer, 26);
  sensors.setLowAlarmTemp(insideThermometer, 22);
  sensors.setHighAlarmTemp(outsideThermometer, 25);
  sensors.setLowAlarmTemp(outsideThermometer, 21);
  
  Serial.print("New insideThermometer ");
  printAlarmInfo(insideThermometer);
  Serial.println();
  
  Serial.print("New outsideThermometer ");
  printAlarmInfo(outsideThermometer);
  Serial.println();

  // attach alarm handler
  sensors.setAlarmHandler(&newAlarmHandler);

}

void loop(void)
{ 
  // ask the devices to measure the temperature
  sensors.requestTemperatures();
  
  // if an alarm condition exists as a result of the most recent
  // requestTemperatures() request, it exists until the next time
  // requestTemperatures() is called AND there isn't an alarm condition
  // on the device
  if (sensors.hasAlarm())
  {
    Serial.println("Oh noes!  There is at least one alarm on the bus.");
  }

  // call alarm handler function defined by sensors.setAlarmHandler
  // for each device reporting an alarm
  sensors.processAlarms();

  if (!sensors.hasAlarm())
  {
    // just print out the current temperature
    printCurrentTemp(insideThermometer);
    printCurrentTemp(outsideThermometer);
  }
  
  delay(1000);
}

[Reply #3 on:]

in the lib there are functions to get the temperature.

Code:

void loop()
{
  sensors.requestTemperatures();

  float T1 = sensors.getTempC(insideThermometer);
  float T2 = sensors.getTempC(outsideThermometer);

  if (abs(T1 -T2) < 0.5)    // best practice: comparing floats is done with an inequallity
  {
    // do something
    moveServo1(T1);
    moveServo2(T2);
  }
}

hope this helps...

[Reply #4 on:]

Thank you  Robtillaart,

 that gets things back on track

 

[Reply #5 on:]

Welcome,

If the sketch works you may post it for people who find this thread usefull (please use the #button for code)

Rob