MQTT – El programador Ibérico

Arduino, Hardware, Software

Making a cheap pedestal fan smarter

1 March, 2022
What more can you ask from a fan? They give us air in hot summers, and they don’t ask for much in return… Compared to the typical air conditioner, which consumes hundreds of watts, even more than a thousand, a pedestal fan is happy with less than 100, usually . Does it make sense to make them smart? Does it at least make more sense than the fact that I am writing this in the middle of January, when this same fan is already stored until summer comes again?

As they say, “everything has already been invented”… There are already fan models with Wi-Fi that can be connected to your home automation system. Simple, you could pay from 70 to 100 euros and boom, you would already have a smart fan. But that’s not how things are done here at El Programador Ibérico 😏.
Let’s start by disassembling the fan and seeing how it works. The front button panel has one input wire (which comes from the live wire) and three output wires, and when each of the buttons is pressed, the circuit between the input cable and one of the output cables is closed, leaving the rest unconnected. We will have to replicate this same operation: receive an order from the home automation server and activate one of 3 outputs, depending on the speed we want, deactivating the others.
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Arduino, Hardware

Homemade doorbell notifier

14 January, 2021

Ding-dong!

Every house has a doorbell. Maybe old, maybe basic… But we don’t always notice when someone rings it. Maybe we are in the exactly opposite side of the house, maybe we are listening to music a bit too high, maybe we are doing some noisy repairs, or because this, our marvelous auditive system was on vacation, and it didn’t pick up the sounds of your doorbell when the Amazon delivery guy rang it.

Adding push notifications to your phone could be the best solution here (and if you have a smartwatch too, even better, because it is even more difficult to not notice the notification). I have not searched a whole lot, but I am sure there are at least a couple of market models of smart doorbells out there, with their fancy melodies and useless apps for your phone, but why should I change my beloved unbranded totally generic classic doorbell? I don’t need an app specifically for the doorbell. I could use PushBullet, which I am already using for my washing machine and will use it for future projects too.

Why not design a homemade solution then? Let’s go 🙂

My basic doorbell receives an AC 230v line when the push button is pressed, not being powered while it is not in use, so the first thing we will need is to detect that 230v signal, as securely as we can, so a fault does not fry our small microcontroller. Talking about them, we will need one with WiFi connection, so why not the same ESP-01 we have used for the previous projects? It is cheap, small and easy to use.

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Arduino, Hardware

Making my air conditioner smarter – Epilogue

13 January, 2021

Making some maintenance in my house, I decided to fix the air conditioner in my living room, a Johnson MGE-30-BC, which has been non-working for a long time.

I bought my house two years ago, and the air conditioner wasn’t working by then. I have always been delaying that repair project because I was expecting the worst possible outcome (maybe the gas escaped and I would have to find the leak, fix it and refill the circuit? maybe the compressor was broken, and I would have to replace it (and also empty and refill the circuit too), maybe more than one thing is faulty and I would have to replace the whole machine?… You know, that kind of repairs, which are not cheap), but… it turned out to be the easiest repair in a long time: the multi-wire cable that connects the inside and outside units has wires of the same color, and two of those wires were connected wrong.

I don’t understand how that would happen… ¿the person who installed it didn’t try it? Maybe he/she thought it was faulty? Why didn’t he/she go to the store to retrieve his/her money? Was he/she just lazy? The only thing that I know is that I have a working aircon in the living room now 😂.

Now that it is working, and being the owner of another aircon in my bedroom which I can control with my phone, I thought the living could not be less, and started once again decoding the remote IR codes, as I did some months ago with my bedroom unit.

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Arduino, Hardware

Making my air conditioner smarter – Part 3

13 January, 2021

<< Continuation of Part 2

Time to end this project and start thinking about the next one 😄.

In the previous post, we ported our code to control the air conditioner to our small ESP-01. Now we need to install everything inside the air conditioner and make it work.

First, we need the small board to power our ESP-01 and connect it to our IR LED. We do not need much: a small voltage regulator (in our case an LM317), a couple of resistors to configure it to 3.3v, a 2×4 female pin connector and a couple of resistors to put the ESP-01 into normal boot mode. The small schematic I came up with is below:

Everything looks ok, let’s assemble it. The easiest and fastest is to use a perfboard, but in the future we try etching them with acid 😊

What to do when you don’t have the exact resistor you need? You stack them in series 😊

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Arduino

Making my washing machine smarter – Part 4

11 January, 2021

<< Continuation of Part 3

Time to start coding the software part of this project. If you remember, the requirement seems to be simple: To make the washing machine send a notificacion when the washing cycle ends (when the door unlocks).

To send these notifications, we could choose one of many routes: e-mail, SMS, push notifications, using a custom app also designed by us… To save time, I decided to use pushbullet, a third party push notification service.

Pushbullet allows us among other things, to send small text notifications to all the devices linked to the service. We could then, from the microcontroller, send a notification and receive it in my phone and my smart watch. I have a small IoT server in my home: an orange PI PC with OpenHAB, which I use to control my smart power outlets. What if I connect my washing machine to that server and make it send the notifications for me? That way, I could check the washing machine state and send a command to start the washing machine cycle, all remotely.

Let’s start with the way of communications, which will have the ESP-01 miccrocontroller with my IoT server. In this case, I decided to use MQTT, for its simplicity: You define channels of communication (topics), the receiver will subscribe to those topics and the sender will publish messages to them. The PubSubClient library will help us use MQTT with ESP8266 microcontrollers.

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