Looks like the Pi 1 used a linear regulator and it was limited to 50ma. Later Pi's all use a switching regulator that can apparently supply 500-800ma on the 3.3v output. We'll find out.

If I turn on signing on the GW, do I have to turn it on for all nodes, or can I use a mix of signed and non-signed nodes?

In reading the comments on one of those, someone noted that with the high power NRF radio, the raspberry pi 1 could not send data via the radio because it didn't have enough power. Am I going to run into the same problem with a Pi Zero W?

@gohan, there are two MQTT plugins for the Vera with varying capabilities. But, the mysensors plugin for Vera doesn't appear to support MQTT at all. I could probably get one of those MQTT plugins working, but I'm not sure how stable they are. I hate installing unstable plugins and having them crash LUUP. I need to maintain a positive WAF (Wife Acceptance Factor), and broken HA doesn't help with that.

I'm building a new gateway with a Pi Zero W. I don't have a case yet. I'm putting the long-range NRF24l01+ radio on it. What's the best way to mount this to the case without making it look like a bomb? Unfortunately, I don't have a 3d printer yet. The best I can come up with so far is to stick a mini breadboard to the top of it and plug the radio into that, but then I still have a bunch of wires sticking out everywhere.

I have a bunch of sensors joined to an ESP8266 gateway. I'm building a new gateway using a Pi Zero W. Can I just shut down the old gateway and do the pairing process over again on the new one? Or, do I have to somehow disassociate the sensors from the old gateway first?

Is it possible to build a gateway that is MQTT, but also listens on port 5003? I want to send my data up to AWS IoT, but I also need port 5003 for Vera integration.

Just wanted to throw this out there as I was revisiting this post today. This could pretty easily be modified to have a digital display with buttons to adjust temperature, and a 5A solid state relay. This would allow you to completely replace the mechanical thermostat.

My thermostat replacement was nearly $40 after shipping, and it's rated at 5A so those 5A relays should work just fine. This would be a cheaper replacement for the mechanical thermostat and would give you better temperature control. Maybe better temp control isn't needed if you're just using for a freezer, but if you're a home brewer and trying to keep fermenters at a constant temperature, this would be very useful. You could even add PID code to it.

I built a temp alarm for my big freezer after I lost about $1k worth of meat and other frozen foods due to a failed thermostat. If the thermostat fails again, I'll build an arduino based one with a screen to set temperatures and a relay to turn it on and off.

I modified the example sketch for the temp sensor to support a buzzer and a mute button. I did this because my ESP8266 gateway doesn't seem to be very reliable, and neither do notifications on the Vera. At least this way, someone will hear it beeping if there's a problem. The device uses a button with a pulldown resistor to ensure that the pin stays LOW when the button is not pressed. When the temperature is >= to the alarmTemp, alarmState goes to true which sounds the buzzer and sets the SLEEP_TIME down to 1 second. If you press the button, it will mute the alarm. The alarmState and mute automatically resets when the temp goes below alarmReset. Note that the temps you set in the sketch will either be F or C depending on what your controller is set up for. I'm using F, and usually keep my freezer at -20F. So I set my alarmTemp to 10F and reset at 0F. If you're using C, you'll want to change this appropriately.

I'm always amazed that you can build stuff like this for like $5.

Note that drilling holes in a modern freezer can be a risky endeavor, because the hot side of the compressor lines run beneath the sides and/or back of the freezer. They aren't exposed anymore. I used my Seek thermal camera to determine exactly where the lines were before I drilled and used a dry erase marker to mark them.

Code below,

Photos here - https://goo.gl/photos/4inkTh6GVhCEupLa8

/**
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * DESCRIPTION
 *
 * Example sketch showing how to send in DS1820B OneWire temperature readings back to the controller
 * http://www.mysensors.org/build/temp
 */


// Enable debug prints to serial monitor
#define MY_DEBUG 

// Enable and select radio type attached
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69

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

#define COMPARE_TEMP 1 // Send temperature only if changed? 1 = Yes 0 = No

#define ONE_WIRE_BUS 3 // Pin where dallase sensor is connected
#define BUZZER 5 
const int buttonPin = 7; // Pin where the mute button is connected
#define MAX_ATTACHED_DS18B20 16
unsigned long SLEEP_TIME = 30000; // Sleep time between reads (in milliseconds)
OneWire oneWire(ONE_WIRE_BUS); // Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
DallasTemperature sensors(&oneWire); // Pass the oneWire reference to Dallas Temperature. 
float lastTemperature[MAX_ATTACHED_DS18B20];
int numSensors=0;
int buttonState = 0;
bool alarmState = false;
bool muteAlarm = false;
float alarmTemp = 10; // Temperature where our alarm goes off. Use F if your gateway is imperial, C if metric
float alarmReset = 0; // Temperature where the alarm resets automatically
bool receivedConfig = false;
bool metric = true;
// Initialize temperature message
MyMessage msg(0,V_TEMP);

void before()
{
  // Startup up the OneWire library
  sensors.begin();
}

void setup()  
{ 
  // requestTemperatures() will not block current thread
  sensors.setWaitForConversion(false);
  pinMode(BUZZER, OUTPUT);
  pinMode(buttonPin, INPUT);
}

void presentation() {
  // Send the sketch version information to the gateway and Controller
  sendSketchInfo("Temperature Sensor", "1.1");

  // Fetch the number of attached temperature sensors  
  numSensors = sensors.getDeviceCount();

  // Present all sensors to controller
  for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {   
     present(i, S_TEMP);
  }
}

void loop()     
{     
  if (alarmState == true && muteAlarm == false) {
    digitalWrite(BUZZER, HIGH);
    delay(1000);
    digitalWrite(BUZZER,LOW);

    buttonState = digitalRead(buttonPin);

    // check if the pushbutton is pressed.
    // if it is, the buttonState is HIGH and we mute the alarm
    if (buttonState == HIGH) {
      muteAlarm = true;
    } 
  }


  
  // Fetch temperatures from Dallas sensors
  sensors.requestTemperatures();

  // query conversion time and sleep until conversion completed
  int16_t conversionTime = sensors.millisToWaitForConversion(sensors.getResolution());
  // sleep() call can be replaced by wait() call if node need to process incoming messages (or if node is repeater)
  sleep(conversionTime);

  // Read temperatures and send them to controller 
  for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {
 
    // Fetch and round temperature to one decimal
    float temperature = static_cast<float>(static_cast<int>((getControllerConfig().isMetric?sensors.getTempCByIndex(i):sensors.getTempFByIndex(i)) * 10.)) / 10.;
    if (alarmState == false && temperature >= alarmTemp) {
      alarmState = true;
      SLEEP_TIME = 1000;  // Set our sleep from 30 seconds to 1 second to facilitate buzzer and intensive monitoring
    }
    if (alarmState == true && temperature <= alarmReset) {
      alarmState = false;
      muteAlarm = false;
      SLEEP_TIME = 30000;
    }
    // Only send data if temperature has changed and no error
    #if COMPARE_TEMP == 1
    if (lastTemperature[i] != temperature && temperature != -127.00 && temperature != 85.00) {
    #else
    if (temperature != -127.00 && temperature != 85.00) {
    #endif
 
      // Send in the new temperature
      send(msg.setSensor(i).set(temperature,1));
      // Save new temperatures for next compare
      lastTemperature[i]=temperature;
    }
  }
  sleep(SLEEP_TIME);
}