{"id":4298,"date":"2024-06-22T17:25:00","date_gmt":"2024-06-22T22:25:00","guid":{"rendered":"https:\/\/jimsghost.place\/?p=4298"},"modified":"2024-12-28T18:00:49","modified_gmt":"2024-12-28T23:00:49","slug":"simple-weather-station-en","status":"publish","type":"post","link":"https:\/\/jimsghost.place\/?p=4298","title":{"rendered":"Simple Weather Station"},"content":{"rendered":"\n

How to spend a lot of effort for seemingly nothing \u2014 and enjoy it.<\/p>\n\n\n\n\n\n\n\n

At first glance, it might seem like this story is about a failed project. But that\u2019s not the case! The project was completed in full and worked brilliantly. So why “seemingly nothing”? That will become clear at the very end.<\/p>\n\n\n\n

So\u2026 The task: to construct a simple weather station with basic functionality for use in automating various smart home functions. Specifically, it will optimize the logic of a lawn irrigation system and indoor lighting control. And, of course, it will inform the meat sacks about all the horrors awaiting them outside should they dare to exit the airlock of their living module on this inhospitable planet.<\/p>\n\n\n\n

As always, I\u2019ll try to cover the topic a bit more broadly than just \u201csolder this to that, shove it in a case, congratulations.\u201d<\/p>\n\n\n\n

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Let\u2019s say that every light switch in the house currently has a built-in sensor that measures the level of illumination. The automation of the switch\u2019s operation is tied to this level, combined with a motion sensor.<\/p>\n\n\n\n

In practice, assessing whether a room is “dark” or “bright” turned out to be a non-trivial task. After all, the sensor measures the level of illumination only at its own specific location. For instance, on a cloudy day, the sensor might determine that it is “dark” in its spot, even though there is still plenty of light overall in the room to avoid turning on the lamp. A similar situation arises in the evening when lights in other parts of the house turn on or off, altering the overall ambient light level throughout the home.<\/p>\n\n\n\n

This means that the “dark” or “bright” parameter is not tied to the sensor\u2019s actual readings but rather to very inconsistent and subjective human perceptions.<\/p>\n\n\n\n

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I conducted an experiment. Over the course of a week, at different times of day and night, I used a handheld lux meter to jot down the illumination levels at which I felt it was “dark” enough in the room to justify turning on the light.<\/p>\n\n\n\n

The experiment showed that the same lux meter reading, taken at the same point in the room, could be subjectively perceived as “dark” in the evening or “bright” in the morning. The same value!<\/p>\n\n\n\n

This discrepancy arises because the lux meter doesn\u2019t account for a multitude of other factors that together create the overall perception of brightness for a person.<\/p>\n<\/div>\n<\/div>\n<\/blockquote>\n\n\n\n

However, the problem can be solved. The solution is to elevate the measurement to a more global level, where lighting conditions are more consistent. Instead of creating complex algorithms to account for local light sensor conditions\u2014incorporating time of day, coefficients, adjustments, checking the light level in an adjacent room, etc. \u2014 it\u2019s simpler to just “look” at what the lighting conditions are like outside.<\/p>\n\n\n\n

And it worked! The automation immediately began functioning as expected. This was proven by another experiment involving a prototype cobbled together from a controller and a photoresistor, placed outdoors for a couple of days.<\/p>\n\n\n\n

So, what does all this talk about illumination have to do with anything? The answer is simple: “looking at how it\u2019s like outside” is a direct task for a weather station.<\/p>\n\n\n\n

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Here\u2019s another example.<\/p>\n\n\n\n

I have this thing \u2014 an automatic lawn irrigation system for my yard. Essentially, it\u2019s a primitive electronic timer that turns solenoids on and off according to a set schedule.<\/p>\n\n\n\n

Now, here\u2019s the problem\u2026 The weather constantly interferes with the lawn irrigation schedule. Watering grass under the scorching sun at its full 100,000 lx is a terrible idea \u2014 all the grass will “burn.” Fine, then we\u2019ll schedule the irrigation for nighttime. Problem solved? No.<\/p>\n\n\n\n

Because \u2014 subtropical climate. During certain seasons, rain is scheduled for the night. Watering the lawn during rain is a terrible idea. And even the day or two following rain \u2014 also not great. Fine, let\u2019s manually monitor the seasons and switch the irrigation schedule to “once every three days,” hoping that our schedule won\u2019t overlap with the rain\u2019s timetable. Problem solved? No.<\/p>\n\n\n\n

Because now we add the “human factor.” In the hot summer season, it\u2019s quite pleasant to sit on the veranda in the evening over the weekend, enjoying the cool spray of working sprinklers. So, if we\u2019re planning to relax on the veranda and watch the water spray, we have to switch the irrigation schedule to the evening on those days \u2014 but then remember to turn it off at night\u2026<\/p>\n\n\n\n

And so on. In the end, instead of having an automated system, we\u2019re stuck with nearly manual control of the irrigation. Inevitably, this leads to forgetting when, where, and what needs to be turned on or off.<\/p>\n\n\n\n

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To make things worse, the ancient controller would sporadically reboot itself, resetting its settings to “default.” And its “default” was such a nightmare that the sprinkler system became a game of “Russian roulette.” The internal clock would reset to zero, the irrigation time would be set to some arbitrary “6 PM” relative to the reboot time, and the intervals for each sprinkler zone would be assigned completely randomly.<\/p>\n\n\n\n

There was always a chance you\u2019d be unexpectedly soaked head-to-toe at any random time of day or night.<\/p>\n<\/div>\n\n\n\n

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This sprinkler system drove us mad for years!<\/p>\n\n\n\n

Naturally, all these problems can be easily solved with a weather station that knows if it\u2019s dark outside, whether it\u2019s raining right now, when it last rained, what the current temperature is, the relative humidity, the day of the week, the season, and so on.<\/p>\n\n\n\n

By tying the weather station\u2019s data to the logic of the sprinklers, you can not only ensure comfort and joy but also save a significant amount of money for the family budget. Sprinklers are very water-hungry, and in our area, water is a precious resource.<\/p>\n\n\n\n

How the new lawn irrigation control system was implemented is a topic for a separate article. But it was important to mention all of this here to provide a general understanding of why I need a weather station in precisely this form and not any other.<\/p>\n\n\n\n

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Of course, it\u2019s clear without even discussing home automation that a weather station is also needed simply as an informational tool for people.<\/p>\n\n\n\n

Additionally, it must be acknowledged that electricity, the internet, and cellular connectivity in our area are extremely unreliable. I can\u2019t recall a single hurricane where at least one of these essentials didn\u2019t fail. Often, they all go down simultaneously. By now, these outages are the subject of constant jokes and are considered part of the “local charm.”<\/p>\n\n\n\n

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Though, to be honest, there\u2019s not much to laugh about. In recent years, the obvious shortcomings in electricity and communication infrastructure have snowballed into one of the city\u2019s most serious problems. Efforts are underway to address them \u2014 but progress is slow.<\/p>\n\n\n\n

Sure, “Houston strong!” and all that, but\u2026<\/p>\n<\/div>\n<\/div>\n<\/blockquote>\n\n\n\n

In any case, relying on weather apps to pull data from the internet isn\u2019t always practical. Texas is vast, and one weather report doesn\u2019t cover it all. In fact, it often isn\u2019t enough to represent even just Houston. So, if your phone app tells you about pleasant, mild weather with a light breeze in the city, that doesn\u2019t necessarily mean your house on the outskirts isn\u2019t being torn apart by a hurricane at the exact same time.<\/p>\n\n\n\n

In short, a personal, local weather station powered by batteries is a fixture in almost every household here. It\u2019s considered as essential as a microwave or an iron.<\/p>\n\n\n\n

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Up until now, we had been getting by just fine with an old AcuRite weather station (I can\u2019t even recall which model it was anymore):<\/p>\n\n\n\n

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A contraption with a “propeller” sat on the roof, while a display with pretty graphics was inside the house. No wires were needed. Batteries powered both the outdoor and indoor units \u2014 lasting over a year, depending on the brand of batteries.<\/p>\n\n\n\n

For a while, I toyed with the idea of intercepting the data from the sensor array outside and routing it to my smart home server. Naturally, it didn\u2019t support this “out of the box” \u2014 not surprising for a model nearly a dozen years old. Back then, no one really thought much about such integrations. There are several interesting DIY solutions online that I browsed through occasionally, but I wasn\u2019t in any rush to pursue the project.<\/p>\n\n\n\n

And then everything was resolved suddenly and without my involvement.<\/p>\n\n\n\n

One not-so-great day, I glanced at the familiar station display on the wall and saw dashes where the values were supposed to be. A clear sign that data from the sensor array wasn\u2019t being received. I figured the batteries might have died. But no\u2026 it wasn\u2019t the batteries.<\/p>\n\n\n\n

A brief trip to the roof revealed the grim remains of the weather station, which I promptly brought back to the ground:<\/p>\n\n\n\n

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Cthulhu had come through the night before with a thunderstorm, and apparently, that eldritch horror from the depths had finished off the already aging device. One arm of the anemometer had been carried off to R\u2019lyeh. A severed vane feather lay separately on the roof, wedged into the shingles. Water had evidently gotten inside the station, wreaking total fhtagn on the electronics \u2014 the plastic casing had become as brittle as an eggshell, riddled with tiny cracks after a decade of exposure to relentless UV waves.<\/p>\n\n\n\n

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It was sad, of course, but the station had lived a long and honorable life. Almost 12 years! That\u2019s no small lifespan for a household appliance. So, I had no complaints. It had repaid its $100 cost many times over. With due honors, it was laid to rest in the trash bin and remembered fondly.<\/p>\n<\/blockquote>\n\n\n\n

Well, then \u2014 time to find a replacement. But this time, with all new requirements in mind. The choice between “buy” and “build” leaned toward “build.” First, the cost of reliable, modern stations that can integrate with smart home systems is around $200\u2013300. That\u2019s steep. Second, by that point, I already had the necessary knowledge, tools, and parts to build such a station myself without much hassle. Third, I was simply curious to give it a try. And fourth, who\u2019s going to stop me?<\/p>\n\n\n\n

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The project was conditionally divided into two phases. Phase one \u2014 implementing the minimally required functionality. Phase two \u2014 adding extra features.<\/p>\n\n\n\n

The minimally required functionality included: temperature, humidity, pressure, precipitation, and illumination. These were the data points eagerly awaited by a slew of smart home automations, practically squealing with impatience.<\/p>\n\n\n\n

Things like wind speed\/direction, a weather forecast through the end of the Holocene, alerts from the NWS<\/a>, a live stream from Punxsutawney Phil<\/a>, or readings from a “weather rock<\/a>” were categorized as extra features to be addressed in phase two.<\/p>\n\n\n\n

In reality, a weather station is laughably simple. It\u2019s a beginner-level project that\u2019s achievable for anyone even mildly interested in the subject.<\/p>\n\n\n\n

To implement the minimal features, only a few existing, ready-to-use components are needed:<\/p>\n\n\n\n

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BME280<\/figcaption><\/figure>\n\n\n\n
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BH1750<\/figcaption><\/figure>\n\n\n\n
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CPRSDBEX<\/figcaption><\/figure>\n<\/figure>\n\n\n\n