BBQ Temp Controller Build

[Tango2]

I'm in the process of building a BBQ temp controller, and was trying to figure out the best way to remotely monitor/control it. After coming across this website a month or so ago, I'm now running OpenHAB on a RPi2 and have a couple temp sensors deployed around my house.

This project is a little more involved, and I'm sure I'm going to run into roadblocks along the way. My goal is to have a sitemap in OpenHAB that will allow me to set and monitor my desired grill temp, which will control a small fan on my BBQ using a PID algorithm, as well as display the temps of the meat probes so I can know how things are going.

I currently have the sitemap setup in OpenHAB, and have had the code working for the thermocouple temp probes that I will be using for the grill and meat temps. Today I will start trying to get the two to work together, based on the MySensors Serial API. I'll be using the NRF24L01+ radio modules for this. I'll post my code periodically, and hopefully will have some chime in on how to make it work or improve it.

[Tango2]

Below is a very rough sketch of what I have so far. This is not working or tested even yet, but it does compile in Arduino IDE. I will breadboard the sensors I have in the next couple of days and get the basics working, then I will have to figure out how to send the temperatures over to my gateway. Next will be configuring for receiving commands from the gateway/controller to allow me to set my target temperature on the Arduino. Any recommendations are welcomed.

This program is my attempt at creating a BBQ controller for my Big Green Egg using
an arduino to monitor grill and meat temps as well as control a fan to
regulate the grill temperature.

Components used:
- Arduino UNO
- 10CFM Brushless DC Blower
- Level Shifter
- K-type Thermocouple
- K-type Grill Probe
- K-type Meat Probe


Pin assignments:

*/

/*
Tasks:
- Selftest
  - Fan 0-100-0
  - Check for Probes

- Set Grill Temp

- Setup Display
  - Grill Temp
  - Probe 1
  - Probe 2
  - Fan Status
  - Elapsed Time

- Measure Temperature
  - Grill
  - Probe 1
  - Probe 2

- Analyze Temperature
  - PID Contol

- Control Fan
  - PWM Value
  - On/Off

*/

//-------------------------------- Classes ------------------------


//-------------------------------- Includes -----------------------

#include <MySensor.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <SPI.h>
#include <PID_v1.h>

//-------------------------------- Defines ------------------------


#define oneWirePin 9
#define TempPrecision 9
#define MAX_ATTACHED_DS18B20 16

OneWire oneWire(oneWirePin); //Setup oneWire instance to communiate with any oneWire devices
DallasTemperature sensors(&oneWire); //Pass our oneWire referenceto Dallas Temperature.
DeviceAddress Probe0, Probe1, Probe2, Probe3; //Define arrays to hold device addresses.
MySensor gw;
unsigned long SLEEP_TIME = 15000;
float lastTemperature[MAX_ATTACHED_DS18B20];
int numSensors = 3;
boolean receivedConfig = false;
boolean metric = true;
MyMessage msg(0,V_TEMP);

void sketchInfo () {
  gw.begin();
  gw.sendSketchInfo("Temperature Sensor","1.0");
}

void setupProbes () {
  sensors.begin();
  sensors.getAddress(Probe0, 0);
  sensors.getAddress(Probe1, 1);
  sensors.setResolution(Probe0, TempPrecision);
  sensors.setResolution(Probe1, TempPrecision);
}

// Cycle fan from 0-100-0% power over 10 seconds.
void selftestFan () {

}

// Verify which probes are connected and report status for 10 seconds
void selftestProbes () {

}

void printTemperature(DeviceAddress deviceAddress)
{
  float tempC = sensors.getTempC(deviceAddress);
  //Display Temp in °C
  //Serial.print("Temp C: ");
  //Serial.print(tempC);
  //Display Temp in °F
  Serial.print(DallasTemperature::toFahrenheit(tempC));
  Serial.print(" F ");
}

void printData(DeviceAddress deviceAddress)
{
  //Serial.print("Device Address: ");
  //printAddress(deviceAddress);
  //Serial.print(" ");
  printTemperature(deviceAddress);
  //Serial.println();
}

void sendTemps () {
  for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {
    float temperature = static_cast<float>(static_cast<int>((gw.getConfig().isMetric?sensors.getTempCByIndex(i):sensors.getTempFByIndex(i)) * 10.)) /10.;
    gw.send(msg.setSensor(i).set(temperature,1));
    lastTemperature[i]=temperature;
  }
 gw.sleep(SLEEP_TIME);
}
  
void setup() {

  Serial.begin(9600);
  sketchInfo();
  setupProbes();
  //selftestFan();
  //selftestLCD();
}



void loop() {
  // put your main code here, to run repeatedly:

  gw.process();
  sensors.requestTemperatures();
  printTemperature(Probe1);
  printTemperature(Probe2);
  sendTemps();
  //readTemps(Probe0);
  //readTemps(Probe1);
}

[gadu]

Cool project! Following.

[BulldogLowell]

I've been watching this one, but will watch this one evolve too.

Waiting to see if they get a web app done.

[Tango2]

@BulldogLowell
That looks like an interesting project as well. This originally started very similar to that one, and I was planning on using a local LCD on it for the display. I quickly realized that the local LCD would not give me the "warm fuzzy" that checking this remotely would give me. When I started going towards a web interface design, I then realized that I really didn't need the local LCD at all.

I'm not at all good with the programming piece, but I've gotten by so far. We'll see how this works out.

[5546dug]

@Tango2 Check this link, it is something I built for my Big Green Egg BBQ.
It looks like it could be my sensors material.
http://www.susanminor.org/forums/showthread.php?315-PID-Controller
Maybe this may help.

[Tango2]

@5546dug That's an interesting build. I've come across several using a PID controller similar to that, however they have mostly been on electric smokers. My original intent was to do a PWM fan that could be speed controlled, but it was very hard (impossible) for me to find a blower type fan that was PWM-capable. My very initial testing showed that an on/off model would work as well but I haven't tried this on the Big Green Egg yet.

My main concern is being able to feed a temp from my phone back to the arduino controlling this, and being reliable if for some reason wireless connectivity was lost from the arduino. I don't think this should be too hard, but will probably take some trial and error on my part.