Arduino, Raspberry Pi, etc. for home use

[jacob]

I've been reading through a few Arduino books lately. While the projects one can make are magnitudes more exciting than the proto- and breadboard projects that I made 20 years ago (counting in binary with 555s, etc.), they still seem like mostly "toy"-projects in the literal sense, that is, they seem useful when you're building a robot or a gadget from a spy novel, but not so much for anything else.

I know @sky made a project that would automatically water his microgreen trays when the water-level was low. And I've been thinking about making a window fan that reverses direction depending on whether it's warmer inside than outside. I suppose building better temperature control into a coffee machine would also count.

However beyond that, I can't really think of something "useful" in the home that would benefit from DIY electronic control systems. So either I lack imagination or there isn't just that much use for this stuff!?

Any other ideas?

[Lucky C]

If going the computerized route for fan control then you might as well integrate a humidity sensor to calculate dew point or get that data from a local weather station, so that you aren't taking in high humidity air that feels worse just because it is a couple degrees cooler than the indoor air. While you're at it, you could integrate some shutters to stop air leaks when the fans aren't in use.

If you had some indoor plants that didn't get enough light from the window you could monitor light levels and power LEDs as needed without wasting as much electricity. It's hard to get a good payoff growing a few (non-drug-related) plants that require electric lighting but if optimized it might be worth it.

You can use a Raspberry Pi as a Linux PC but I have no idea about the performance and limitations. Again for potentially lower energy usage it might be worth a try.

For the most part I agree that it seems to be used for a lot of wants (media server, magic mirror, etc.) and not truly useful stuff.

[jacob]

I believe https://solar.lowtechmagazine.com/2018/ ... bsite.html runs on a raspberry pi.
If I ever start a new blog, it would likely be something like that.

However, again, that is pretty much also the only use I can imagine for a raspberry pi short of building cute toys like a primitive game console or some such.

[basuragomi]

Arduino is a good introduction, but a lot of people find that they are overly expensive and don't really fit their needs due to being 8-bit microcontrollers. If you can transition from Arduino to cheaper or more powerful controllers you might find more utility in them. Most things in the house that require automation to work at all already have robust automation built in. So in a domestic context Arduinos are best used for back-up systems, repairs or beyond-standard automation.

My father uses his Arduino for prototyping everything. He got sick of replacing his scale batteries so he hacked the whole thing with an Arduino. Then he used the scale as a step counter for his exercise machine. Lately he uses the Arduino to monitor his exercise bike (after the step machine wore out) and hooked it up to the computer so it will auto-wake, play videos and stop the computer from sleeping as soon as he steps on the thing. It also displays the distance ridden directly on top of the video.

If you have rodent problems, an Arduino-powered laser-triggered solenoid+mousetrap combination works way better than relying on a standard mousetrap mechanical trigger - mice often are able to eat the bait without tripping the mechanical trigger. It is cheaper than buying 120VAC components as well.

Custom computer controls. Want to use an engine pulley for a scrollwheel instead of a dinky little mousewheel that's probably giving you RSI? 3D mouse? Want a TV lamp that changes colour to match your computer screen like you're in a retro-future 60's?

Personal readouts. I've seen a project that hacked transit radio feeds to display when the next morning commute bus would arrive. It didn't use Arduino (can't handle DSP at that speed), but something that pulls the next bus time from a web API instead could use one.

Home automation: Surveillance cameras, phone-activated locks, timers, automatically changing RGB bulb hues for time of day, engine block heaters, sump overflow alarms, washer flood alarms, radon-triggered basement fans, time-based oven cut-offs, fridge temperature loggers. Adding another layer before human checks. Some of this would likely be useful to install for aging people who might become forgetful. Unfortunately Arduinos are not powerful enough for AI systems like cat flaps that use CV to only let in your specific cat.

[sky]

If you were to control insulated window blinds, you could have your device check the weather report and open the blinds on a sunny day for solar heat gain. You can get a clone arduino and a shield with 4 relays for under $20 on aliexpress.

Many years ago, I set up an Rpi as a desktop. It was slowwwww. I have heard that the latest generation 4B is quite fast at $55. I heard this recently and have not researched it yet. My old laptop is not very fast and it is quite possible that an Rpi would be an upgrade.

[5ts]

I have thought about this a lot and I don't see a broad use, only bespoke solutions. I like everything about the project, and it's nice for tinkering and solving small problems.

[Gilberto de Piento]

I talked to someone that built a system to close a chicken coop door based on something like time of sunset.

[7Wannabe5]

Make your house into a biosphere with all sorts of cool stuff like aquaculture and automated modular mini greenhouses powered with solar. Obviously, it would be more fun if you added some mechanical components like a robot basement dwelling meat rabbit herder.

[Loner]

A friend of mine used it to open the door of his apartment building with his cellphone. He somehow connected the RP to the button in his apartment that unlocks the door of the condo, and then used the cellphone to trigger (via text message, or email, or some other technical mean that I forgot) the button. Cool projet though mostly useless like most other home automation.

[Toska2]

I would make my own programmable thermostat. The reason is that most newer ones have a very narrow temperature range from the set point; +-1 degree for my honeywell. This causes my single stage furnace to kick on and off more than I'd like.

My coworker had a modulating gas valve furnace that was designed to reduce the short cycling. He was replacing the valve every other year. He traded an inconvenience for a costly problem.

* I see Protech thermostats have an adjustable range 0.5°, 1.0° & 2°

[Lucky C]

There could be a bunch more uses at the decentralized village (or SHTF community if you're a pessimist) level.
- It would make more sense to automate garden maintenance at the community level than just for your own small garden
- Tool library check in/out system
- Small scale crafting/manufacturing (Raspberry Pi CNC)
- Mechanical energy storage system
- Server for wireless network for you and your neighbors (wireless community network) for communication, media sharing, community currency system, or whatever you can dream up!

As someone who lives in an area that tries to uphold the feel of community and villages (originally mill villages surrounded by farmlands), I bet I could find one or two people who would be interested in trying to get something like this started.

[fiby41]

Instructables has many diy projects. How many of them are useful as opposed to just for fun depends.

Mentioned in this thread

https://www.instructables.com/id/Temper ... y-Arduino/
Temperature and humidity

https://www.instructables.com/id/Smart-Central-Lock/
Locking and unlocking things using phone

A lot of clocks of bigato's liking.

[Sclass]

I did a usb interfaced IR remote for my mom’s window AC unit with an Arduino UNO. In her early Alzheimer’s days she wouldn’t turn it on during hot weather. Then when I’d Skype in and tell her to turn it on she’d leave it on and the room would get cold.

So I built a board to piggy back on the remote control for the AC so I could turn it on and off and set the temp. Arduino is powerful enough to operate as a stand-alone IRDA transceiver but I was in a hurry and it was easier to solder some MOSFETs to the existing IR unit and wire to the Arduino ports. If I’d been ambitious I’d decode the OOK messages and write my own modulation routine. But I was just in a hurry to get her AC controllable remotely. That way when I Skyped mom I could use logmein to operate her AC. Arduino was a great shortcut even though I was fully capable of doing a custom controller.

I have personal experience marketing a high performance chemical sample handler using an Arduino. Not a toy. $25,000 sample prep reactor to work upstream of a chemical analysis system I built. I didn’t want it done this way but it was at a time when I got incapacitated and senior management decided they could build the product in my absence if they could avoid custom embedded hardware. Arduino allowed a team of scientists and pure PC programmers to basically make a piece of electromechanical hardware without much electronic design or micro coding. No HW engineer required. I was pretty happy at first because it meant less work for me.

It had disastrous results a year down the line for a bunch of reasons. I was forced to help the team debug it. I refused to fix it after I documented the issues. I retired instead. The entire team was let,go shortly after because besides not having the specialized skills to design a microprocessor based product, they couldn’t debug one even if it was Arduino. I watched from my beach house as the entire product line was taken off the website.

So can you build more than toys? Sure you can. The Creality Ender 3d printer is based on an Arduino board. I think open source project was called Marlin. It started out as an open source Arduino project and it was commercialized into a fine 3d printer. There are many other products out there that started as Arduino.

[Sclass]

I would make my own programmable thermostat. The reason is that most newer ones have a very narrow temperature range from the set point; +-1 degree for my honeywell. This causes my single stage furnace to kick on and off more than I'd like.

My coworker had a modulating gas valve furnace that was designed to reduce the short cycling. He was replacing the valve every other year. He traded an inconvenience for a costly problem.

* I see Protech thermostats have an adjustable range 0.5°, 1.0° & 2°

I have this exact problem in my rental. The control band is too tight and it kills the valve. I have my attempt at fixing the valve in the fixit log.

My Honeywell thermostat needs to have a wider control band. I’m assuming houses got better insulation in recent history so they feel it is okay to design their controller this way. It’s annoying how often my furnace lights off. The old mercury bulb thermostats had much wider swings. The problem with using an Arduino is power consumption. The board isn’t built for battery operation. You’ll need to buck down your 24v from the furnace or use an adapter.

[J_]

@OP: I started last year with "electronics for dummies" and made my own electric generator from a by my modfied old bicycle. For me it is not to invent new gadgets or smart electronic household management. It is much more basic. First thing I made my own is a little torch with one white LED and a resistor for reading in bed without disturbing DW. For power I use a little LiPo 5 Ah powerpack 5V DC, it last ages..I can upload this power pack by cycling my generator fiercely by about two hours..
And then I realised: It is this becoming aware of how much (human) power it cost to generate one load for a small power pack. I have become even more aware of not spoiling electric energy...

I am in awe about solar, which can appearantly generate electricity with ease.

I have noticed that loading a standard acid/lead battery costs per Ah a lot more energy than a LiPo battery. Afterwards I see the logic of it. By loading a LiPo battery you are directly storing electrons, in a acid/lead battery the extra chemical process before pushing electrons cost energy itself.
This is an other lesson I got from my electronics tinkering.

TL;DR tinkering with basic electronics gives insight and expieriences and is useful in itself.

[Sclass]

For some reason, it’s very satisfying to read this hahaha

This was an insane story and it made me hate Arduinos. However my disdain was misplaced. We were using the board blindly. By using their hw, OS, bootloader and libraries you are basically inviting unknown engineers to your team. As I debugged the hw I found a lot of problems that the open source community had naively introduced. Our team was indiscriminate when they linked downloaded free libraries for critical functions. We found the code would work well for weeks then suddenly crash on a divide by 0 as a counter unexpectedly rolled over one day a month. It took forever to find this sh.t. I suspected some of the libraries our guys linked came from 13 yo developers in the third world.

In reality Arduino is an amazing platform. It is easy. It can save a lot of dev time. But like everything it has limits. At least for the Duo and Uno the hw and fw was naively architected. But the creators were young guys and at that point they hadn’t seen much.

An example of how good the platform can be is Marlin 3d printing. Basically Creality, my new toy, was created around Arduino and a huge open source project. Creality couldn’t have done this starting from zero. They basically packaged up the free work, redesigned their own version of the board and boom they made an economical yet high performance printer. That is Arduino at it’s best.

If you’re worried about cost there are a ton of cheap code compatible clones out there from China. Trace for trace, pin for pin, chip for chip they are the same. Depends on how you feel about piracy . They are a fraction of the price but frowned upon by the community.

Good luck and have fun. I’ve recommended this stuff before to posts here asking about low cost electronic control and monitoring. Shallow learning curve. Sparkfun is a good place to get stuff. It is easily approachable. The examples look like toys because they are the general interest examples. The educational books are like Make Magazine...fun general interest apps. You need to dig deeper into specific communities to see the really neat apps like autonomous flight, Marlin or Astronomy for example.

Have fun.

[jacob]

@Sclass - Oh man! That [first paragraph] is so common in scientific research that cursing other people's code is almost a lifestyle. Probably why the instinct is to 1) either reprogram the entire code (incl. libraries) from scratch; or 2) find a version that has existed a long time in the hope that all the bugs have been rooted out. Scientists aren't necessarily all good programmers (most are self-taught) and some rely on the good old observation that "shit rolls downhill" so as long as they're the first to publish, it doesn't matter so much that the code/results are buggy. It was somewhat of a mental transition for me to move from scientific research, where run-time errors were fixed by tweaking the code a bit (that's the shit that ends up downhill) and restarting until it works, to financial engineering production codes where run-time failures could be potentially catastrophic (google Knight Capital for an example). The coding-mindsets between [scientific] hacking and proper engineering are completely different.

Here's a typical example of a quick fix to divide by zero that one might find in a research code: y:=a*x/(y+1e-10) ... insofar the y~0 range wasn't deemed important for the particular paper/problem that the "programmer" was working on. Then the code (rarely documented) is handed over to the next person.

[tango]

I got back into electronics earlier this year, with a month or two foray into arduino. After a few projects, I got over the fun, and then realized that many "useful" projects are likely to be available for a cost that is much less than my time. I can see niche needs for something not commercially available, like DIY electronic art, maybe DIY RC aircraft.

My first project was a cat feeder. It was useful and saved some money, as equivalent higher end commercial cat feeders can cost ~$100. However, the hardest part was not even electronics related. Turns out dry cat food does not behave like a fluid and the mechanical part to measure a tablespoon of food is tricky.

Other projects included a 2 wheel balancing robot (wanted to learn a PID controller algorithm), and a DIY sleep tracker (interesting to play with motion sensors, sound detection, etc., but again not worth my time when a free smartphone app does the same thing).

Next projects on my todo list are not arduino related - I'd like to rebuild a 555 and 741 with discrete transistors, just to learn/play.

[Sclass]

After a few projects, I got over the fun, and then realized that many "useful" projects are likely to be available for a cost that is much less than my time. I can see niche needs for something not commercially available, like DIY electronic art, maybe DIY RC aircraft.

Isn’t this right. I had a lot of home automation problems to work out at my mother’s home while she steadily declined into dementia. Between webcams, Skype, cheap PCs, Z-wave lighting controls, burglar/smoke/CO alarms, IOT HVAC, smart locks, etc. I had 95% of the problems under control with commercial products. 3% needed custom engineering. 2% were not easily solvable and required human intervention.

Being stressed to the eyeballs I didn’t want to take on any engineering projects. I looked into making an Alien 2 type Sygourney Weaver robot to pick up my mom when she’d fall and couldn’t get up...she literally forgot how to get up. It was a problem for a few months. Basically I’d need a forklift capable of lifting a human into a chair or bed that I could pilot remotely. I just hired a person in the end to be there all the time.

Of course building this last 5% has the benefit that you can package and market the gear once it’s done. This reminds me of my first boss telling me not to build what we could buy. What he meant was don’t waste time building something where we will enter a market without a competitive advantage. This is extreme and I still like sewing clothes and camera bags, but as a business owner I saw his point. I guess it isn’t that you can just buy a lot of commercialized electronic products, it’s that they’re really cheap too considering the engineering time that is put in.

I guess the thinking is flawed somewhat. I can hear the perma culture types grumbling now. It’s like saying why recycle a plastic bottle when it’s cheaper to just mold a fresh one.

@jacob mentions 555 circuits. If you type 555 one shot timer etc. into eBay you see a variety of 555 pcbs built up with timing caps, jumpers and relays for one shot, astable oscillating etc. prebuilt. You don’t even have to wire one up. There are ones for op amps, PWM speed control, Bluetooth. I just built a Bluetooth speaker system for my shop using one of these $3 Bluetooth + power amplifier boards. No building required. $2 garage sale speakers from 1980 (Realistic Minimus 7s) + $3 Bluetooth pcb.

It’s like 95% of everything you need to make is made and cheap. How boring is that!

Has anyone noticed how many Pi apps there are in the real world controlling serious stuff? I see a lot of industrial controls being done this way. You can bootstrap your startup fast by bolting in a Pi and using all the open source libraries. My friend just did a pollution monitoring system for big cities and basically did all the comms and computing with a Pi. No proprietary embedded system, costly RTOS, slow firmware coders etc. Boom, product.

This has opened up vulnerabilities everywhere. I mean you can conceivably hack the charge controllers in the backup batteries in a server farm and flood the place with hydrogen. I loved Mr. Robot. They did some Pi hacks in the story.

A long this line I met a guy selling MCUs at Design Con for lighting control and he argued that his proprietary designs were better because they were less vulnerable to hackers than those running open source OS. Basically you cannot hack what you cannot read about online...at least remotely. No using his cpu as a launch pad because it was too weak for an attack. A lot of the webcam and HVAC hacking is possible because the systems are commercialized versions of well documented open source projects. And, they are way more powerful than they need to be for their intended use.

Not saying there is a right or wrong. The world is going a certain way no matter what.

[sky]

I set up a Rpi 4 as a desktop with 64 bit Ubuntu and overclocked to 2Ghz. I am very impressed so far. I already had the peripherals: powered usb hub, monitor, micro HDMI cable, usb headphone and microphone jack, usb mouse and keyboard. I bought a kit with a 4 Gb RAM Rpi 4 and power supply, and I bought an aluminum heatsink case. It seems to run OK without a fan. 1080p Youtube video looks good. I also bought a 128 Gb SD card and will probably add a 1T ssd external drive.

In the past I saw Rpi projects as geeky hobbies, but the Rpi 4 is a good desktop, at least when set up with Ubuntu. It runs about 65C while running video. Over 85C it will automatically throttle back the overclocking to standard 1.5Ghz, but I have not seen those temps yet. I have a fan I can blow over it but it is noisey, I prefer to run it without a fan.

For years, I have been using a laptop as my main pc. I much prefer working on a desktop to a laptop.