Multiple Dallas sensors on one bus

I have done a couple of arduino projects but am new to photon.

I We have a fermentation temperature control system running on an arduino that I would like to update and move to a photon. so I thought I would start with a simple multiple sensor sketch ie the example provided from the arduino site.

Heres the code

// This #include statement was automatically added by the Particle IDE.
#include "OneWire/OneWire.h"

// This #include statement was automatically added by the Particle IDE.
#include "spark-dallas-temperature/spark-dallas-temperature.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;

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

  // Start up the library

  // locate devices on the bus
  Serial.print("Locating devices...");
  Serial.print("Found ");
  Serial.print(sensors.getDeviceCount(), DEC);
  Serial.println(" devices.");

  // report parasite power requirements
  Serial.print("Parasite power is: "); 
  if (sensors.isParasitePowerMode()) Serial.println("ON");
  else Serial.println("OFF");

  // Assign address manually. The addresses below will beed to be changed
  // to valid device addresses on your bus. Device address can be retrieved
  // by using either or individually via
  // sensors.getAddress(deviceAddress, index)
  //insideThermometer = { 0x28, 0x1D, 0x39, 0x31, 0x2, 0x0, 0x0, 0xF0 };
  //outsideThermometer   = { 0x28, 0x3F, 0x1C, 0x31, 0x2, 0x0, 0x0, 0x2 };

  // Search for devices on the bus and assign based on an index. Ideally,
  // you would do this to initially discover addresses on the bus and then 
  // use those addresses and manually assign them (see above) once you know 
  // the devices on your bus (and assuming they don't change).
  // method 1: by 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"); 

  // method 2: search()
  // search() looks for the next device. Returns 1 if a new address has been
  // returned. A zero might mean that the bus is shorted, there are no devices, 
  // or you have already retrieved all of them. It might be a good idea to 
  // check the CRC to make sure you didn't get garbage. The order is 
  // deterministic. You will always get the same devices in the same order
  // Must be called before search()
  // assigns the first address found to insideThermometer
  //if (! Serial.println("Unable to find address for insideThermometer");
  // assigns the seconds address found to outsideThermometer
  //if (! Serial.println("Unable to find address for outsideThermometer");

  // show the addresses we found on the bus
  Serial.print("Device 0 Address: ");

  Serial.print("Device 1 Address: ");

  // set the resolution to 9 bit per device
  sensors.setResolution(insideThermometer, TEMPERATURE_PRECISION);
  sensors.setResolution(outsideThermometer, TEMPERATURE_PRECISION);

  Serial.print("Device 0 Resolution: ");
  Serial.print(sensors.getResolution(insideThermometer), DEC); 

  Serial.print("Device 1 Resolution: ");
  Serial.print(sensors.getResolution(outsideThermometer), DEC); 

// function to print a device address
void printAddress(DeviceAddress deviceAddress)
  for (uint8_t i = 0; i < 8; i++)
    // zero pad the address if necessary
    if (deviceAddress[i] < 16) Serial.print("0");
    Serial.print(deviceAddress[i], HEX);

// function to print the temperature for a device
void printTemperature(DeviceAddress deviceAddress)
  float tempC = sensors.getTempC(deviceAddress);
  Serial.print("Temp C: ");
  Serial.print(" Temp F: ");

// function to print a device's resolution
void printResolution(DeviceAddress deviceAddress)
  Serial.print("Resolution: ");

// main function to print information about a device
void printData(DeviceAddress deviceAddress)
  Serial.print("Device Address: ");
  Serial.print(" ");

 * Main function, calls the temperatures in a loop.
void loop(void)
  // call sensors.requestTemperatures() to issue a global temperature 
  // request to all devices on the bus
  Serial.print("Requesting temperatures...");

  // print the device information

I have replaced the libraries with photon’s libraries and added the pragma line and here are the errors

dallas_multiple.cpp:1:0: warning: ignoring #pragma SPARK_NO_PREPROCESSOR  [-Wunknown-pragmas]
dallas_multiple.cpp: In function 'void setup()':
dallas_multiple.cpp:74:33: error: 'printAddress' was not declared in this scope

make[2]: *** [../build/target/user/platform-0-ldallas_multiple.o] Error 1
make[1]: *** [user] Error 2
make: *** [main] Error 2
Error: Could not compile. Please review your code.

First whats the deal with needing to shut down the pre-processor?

I guess I just am confused about the difference between arduino and photon.

thanks for your help


You can try without #pragma if it builds you won’t need it :wink:
For the what it’s for: Sometimes the preproc messes the code up and so you might want it off.

But if you have it off, you need to

  • provide function prototypes (hence the not declared error) and
  • add #include "application.h"
1 Like

Hi @murmsk,

The forums noticed you created two accounts instead of reusing your original account (murmsk vs. murmsk1), so that’s why it got flagged. Can you log back into your original account?

Wiring (Arduino language of choice) does some stuff for free for you, that C/C++ usually requires. In this case, when you declare a function like:

void DoStuff(int someVar) {
// stuff.

C/C++ wants you to declare it ahead of time like this:

void DoStuff(int someVar);

// <snip!> 
// ...

void DoStuff(int someVar) {
// stuff.

So the preprocessor does this for you in the main project file, or the “.ino” file.