I am currently undertaking a project where I am attempting to build a bluetooth thermometer using an arduino. I have the temperature sensor working and returning temperature readings via a usb connection to the serial monitor in the Arduino IDE using the following code.

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

Timer t;

// Data wire is plugged into pin 10 on the Arduino
#define ONE_WIRE_BUS 10

// Setup a oneWire instance to communicate with any OneWire devices
OneWire oneWire(ONE_WIRE_BUS);

DallasTemperature sensors(&oneWire);

DeviceAddress insideThermometer = { 0x28, 0x94, 0xE2, 0xDF, 0x02, 0x00, 0x00, 0xFE };

void setup(void)
  // start serial port
  // Start up the library
  // set the resolution to 10 bit (good enough?)
  sensors.setResolution(insideThermometer, 10);
  int tickEvent = t.every(3000,doTempReading);


void loop()

void printTemperature(DeviceAddress deviceAddress)
  float tempC = sensors.getTempC(deviceAddress);
  if (tempC == -127.00) {
    Serial.print("Error getting temperature");
  } else {
    Serial.print("C: ");

void doTempReading()
  Serial.print("Getting temperatures...\n\r");

  Serial.print("Inside temperature is: ");

I now want to try and transmit the readings via a bluetooth connection using the HC 05 module to a raspberry pi which will record the data.

I have done a lot of research and tried several different techniques and can't understand how to go about it.

What mode does the HC 05 need to be in? (Command AT/slave/data/etc.) How should it be wired (I have found several different methods using various resistors and capacitors and unsure which to follow). How should I pair it with the Raspberry pi?

Thanks in advance for any help.

  • 1
    have you tried searching "Arduino HC05" in google?
    – duck
    Commented Feb 22, 2017 at 8:25

1 Answer 1


I know this is old but to help out newcomers:

Here's a place you can begin https://create.arduino.cc/projecthub/millerman4487/view-serial-monitor-over-bluetooth-fbb0e5

The wiring depends on which arduino board you are using and the model of your HC-05 BT module. mine uses 4 pins VCC (5v) GND (ground) TX --> TX and RX --> RX

You should be able to google the wiring for your module, and connect to the raspberry pi after you install bluetooth on raspberry pi

sudo apt-get install bluetooth bluez blueman

sudo reboot

Navigate to new bluetooth interface in menu bar through

  • preferences
  • bluetooth

Add new device, turn arduino on with BT module plugged in and make sure your HC-05 module is blinking red, and you should see a pair connection named HC-05 on raspberry pi. Password is 1234

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.