Upgraded kennel temperature monitor

Introduction

Already built the basic kennel temperature monitor? Now build an even better one. It sends notifications to your phone, so you'll know about a cold kennel wherever you are. 🐶

In this project, you will learn to set up the box to send you a message when the temperature drops below a value you set. 👌 The box won't start barking, but it's still a great project. 🐩

You'll find the basic version of this project here: A temperature watch for your furry watchman: check the temperature in your dog's kennel.

Once again, the basic HARDWARIO set is all you need: the Start Set.

Prepare Node-RED

1. This project uses the familiar twr-radio-push-button firmware. Already flashed it? Then don't wait: pair the box with the Radio Dongle.

2. In Playground, switch to the Functions tab and place the same nodes on the canvas as in the basic version of the project:

• one mqtt in node from the network section, with this Topic again:

node/push-button:0/thermometer/0:1/temperature

• and a gauge, that is a Gauge node from the Dashboard section. It should show a range of −15 to 40 °C. Give it a name so you can find your way around. ✍️

Hold on to your hats, on we go. 🎩

Prepare Blynk IoT for the alert

The temperature alert reaches your phone as a push notification from the Blynk IoT app. That's what makes the box smart. 😎 Node-RED sends the text of the alert to Blynk, and a Blynk automation turns every new message into a notification.

1. If you don't have a Blynk IoT account yet, create one. The free plan is enough for this project: at the time of writing, it includes push notifications in the app and up to five automations.

2. Create a device template. Blynk's quick guide shows you how. You can also reuse a template from an earlier project.

3. In the template, open the Datastreams tab, click New Datastream and choose Virtual Pin. Name the datastream (for example Message), pick a free pin (for example V2) and set the Data Type to String, because the notification will carry your own text.

4. In the datastream settings, let automations use it as a trigger: in the Automations section, turn on Use as Condition. Create the datastream and save the template.

5. Create a device from the template: in Devices, add a new device, choose your template and give the device a name. You'll find its Auth Token on the device's Device Info tab. You'll need it in Node-RED.

Create the automation

1. Open Automations in Blynk and create a new automation. For the condition (When), choose Device State, then your device, your datastream and Is Any. The automation will then react to every message, even when it's the same as the last one.

2. Under Do this, add the action that sends a notification to the mobile app (Send In-App Notifications) and choose yourself as the recipient. Put the Trigger value placeholder ({TRIGGER_VALUE}) in the message. Blynk replaces it with the text that Node-RED sends.

3. Name the automation. Limit period sets how soon the automation may run again. The box keeps reporting the temperature while the kennel is cold, so pick a longer period, such as an hour: one alert is enough, you don't need one for every reading. Save the automation.

4. Download the Blynk IoT app to your phone from the App Store or Google Play and sign in with the same account. Make sure notifications are allowed for the app so the alert can appear. 📱 But first you have to upgrade Node-RED, or nothing will happen.

Upgrade Node-RED

1. Go back to your computer and set up more features in Playground. The first is the phone notification, which you build from three nodes.

• First: a Switch node from the Function section.

In the node, set the same as in the screenshot below:

a. use msg.payload as the property (Property),

b. send the notification when the temperature drops to the value of the flow.optimalTemp variable (for example −15 °C) or below. Use the less-than-or-equal operator <= (the screenshot still shows ==, so change it).

• Second: a Change node from the same section. It sets the message you get on your phone.

In the node, set what your phone will tell you when the temperature in the kennel drops below the minimum you set. For example It's too cold in the kennel.

Our tip: Write the message without accented letters. Unfortunately, Blynk can't display them.

• Third: the write node from the Blynk IoT section. It links the flow to your phone. Leave the Blynk ws section alone: it belongs to the old Blynk, which no longer works. Double-click the node to open it. Next to Connection you'll see a small pencil. Click it and a new window opens. In the Url field enter blynk.cloud, and copy the Auth Token and Template ID from the Blynk web app on your computer: the Auth Token is on the device's Device Info tab, the Template ID in the template details. Confirm with Add.

Then, in the Virtual Pin field, enter the number of your datastream's pin (2 for V2). That's what turns a too-cold reading into a push notification: the node writes the message to the datastream, and the automation sends it on. Confirm with Done.

Our tip: Name the connection in the Name field so you'll recognize it later.

Add the flow that watches the optimal temperature

1. Now for the icing on the cake. This flow has two nodes.

The first is a Numeric node from the Dashboard section. Sounds like a comic-book villain, doesn't it? But now it's on your side.

With the Numeric node, you set the lowest acceptable temperature right from the Dashboard in Playground. That makes the threshold easy to change.

2. In the node, set the unit (°C), the temperature range (−15 to 50) and the node name.

3. Place another Change node next to it.

4. Set it so that the minimum temperature (optimalTemp) updates right away whenever the Numeric node changes. Follow the screenshot.

5. Now all that's left is to wire the nodes as in the screenshot and confirm with Deploy. 🙌 The MQTT node feeds both the gauge and the Switch node, then Switch ➡️ Change ➡️ write; in the second flow, Numeric ➡️ Change. The screenshot comes from an older version of the project: it ends the first flow with the old Blynk notify node and has a few more Blynk nodes. Use your write node in place of notify and leave out the other Blynk nodes.

Ready, steady, go!

1. Stick the box back on the inside wall of the kennel.
2. You'll see the temperature measured in the kennel in Playground on the Dashboard tab…

3. …and above all, you get a notification on your phone if your dog is cold, so you can check on the kennel anytime, from anywhere. 🕵️ Happy dog = good dog! 🐕