Miscellaneous Arduino bits and pieces | Hacker News Reader

Miscellaneous Arduino bits and pieces

vwlowen.co.uk

158 pointsJerry256 comments

I love this kind of stuff. I recently built a slow cooker controller to make yogurt that essentially consisted of an Atmel ATmega328 (same as the Arduino Uno) controlling a relay using a DS18B20 digital thermometer. Then, when I was building it, I thought it'd be cool to have a touch screen display to set the desired temperature. Then, I figured that I might as well power the Arduino using the mains supply instead of having a separate 5V input on the box.

In the end, I learned about mains filtering, switch mode power supplies, safety clearances, fail-safety, microcontrollers and programming touch screens all at the same time. Despite there being cheaper, off-the-shelf solutions available, I preferred this approach.

One downside I've found with hobbies like this: milling enclosures for the electronics is expensive in terms of either money (to have it done externally) or in terms of favours from your machinist colleagues. For anything beyond holes drilled with a drill press, I have to ask a friendly technician where I work. If enclosures/panels could be milled as cheaply as PCBs can be printed, that would be awesome.

You can use PCB as a front panel. It has arbitrary routing, colored soldermask (as background), silkscreen (as labeling).

Some enclosures are extruded aluminum with screw on end caps. If your device is suited to the endcap being made of PCB, you just have another PCB (printed end panel?) to layout.

Here's one example video that shows the technique: https://www.youtube.com/watch?v=Yj0Bv4UEFSs&feature=youtu.be...

Here's another nice tutorial. It looks like it's a nice way to make sturdy custom enclosures.

https://hackaday.com/2015/06/03/how-to-build-beautiful-enclo...

Laser cut acrylic is a lot cheaper and a lot easier. You can even make fairly complex designs in two dimensions if you're willing to layer "rings" of the acrylic.

Though I also recently did a project built inside of a section of PVC pipe. https://youtu.be/O6hGviGHaFY

3d printers are much cheaper nowadays. Not worth it for a one-off, but the price point (a few hundred USD) seems fairly reasonable for hobbyists IMO.

CNC machines are also cheaper these days, but ones that can mill metal are more expensive ($2k+ as far as I've found). Too much for the casual hobbyist, I think.

Check out if there's a Hackerspace in your city. There's a good chance they have a mill you could use - along of plenty of other people interested in these kinds of hobbies.

An alternative is things like 3D but on-demand printing at places like shapeways. You can get steel or aluminium done.

Perhaps there's something similar for CNC?

Junction boxes are a cheap alternative.

Find the box first, adapt the PCB to fit it.

That's what I generally do - but putting buttons and displays on the box is what requires drilling/milling.

seeedstudio offers cheap 3d-printing, acrylic laser cutting too. Haven't tried them though, so can't judge on the quality, but they do have a good reputation, and it is cheap, so that might be worth a shot.

And the best bit: if it breaks you can repair it yourself!

meta: I really like these kind of blogs which are more or less a braindump with heart to it. I'm sure there are many nice nuggets of wisdom and experience if you go through the posts.

To take an example, http://vwlowen.co.uk/arduino/spectrum-analyser/spectrum-anal... about taking a simple 2.4 GHz module and building a spectrum analyzer, is a nice post. You can tell he enjoyed doing it.

When the Web 5.0 is all hosted on Facebook, the best and more impassioned learning material will still be hand-written in HTML 4 on some old radio ham's personal web site that's been lovingly crafted for some 30 years.

If you can stand the video format, this one is unusually rewarding for being a youtube channel:

https://www.youtube.com/user/mikeselectricstuff

I started with this one:

https://www.youtube.com/watch?v=la-sGpTpkxE

"My old BBC Micro system" ... which kind of established his credibilities in my mind, and then I just kept going, devouring his entire channel. Recommended - this guy knows his stuff, and unlike certain other youtube channels in this genre there is no annoying bravado.

Watching that BBC Micro video made me sorry i missed that era. Doing anything like that these days would be just, ugh, painful. Too many layers, both hardware and software, to dig through to get anything close to brass tacks, and we keep adding more every odd year or so...

Don't be sad, there are plenty of opportunity still! And, there's much more easily found information and help :)

A suggestion is to buy eg a MSP430 Launchpad ($10) or STM8 development board (<$1 on Aliexpress) and write simple programs for those. Those cpus are very simple and great starting points.

One of my long-time project ideas is a BASIC interpreter (Commodore-style) for the ESP8266 or one of the more powerful Arduinos, with statements to control GPIO pins or I2C devices and a web-based REPL. It would be great for teaching.

Have you seen this? BASIC interpreter hidden in the ESP32 ROM.

https://hackaday.com/2016/10/27/basic-interpreter-hidden-in-...

That's pretty close indeed! Lost my idea (almost, the web-based IDE would be a bit easier to work with, and TinyBasic did not have strings or floating point), but on the other hand it must have been a good one. ;-)

You can simulate those old 8 bitters easily enough on modern hardware and re-live that time to your hearts content.

You'll become an ace at optimization and memory conservation.

A rack version of a BBC Model B, nice.

meta-meta: reading my own comment above, I can see how it is actually quite similar to those auto-generated spambot-comments in format, I hope it doesn't say much about my inner self :S. Then again, that's just what a spambot would say.

You're in a desert walking along in the sand when all of the sudden you look down, and you see a tortoise, it's crawling toward you. You reach down, you flip the tortoise over on it's back. The tortoise lays on it's back, it's belly baking in the hot sun, beating it's legs trying to turn it'self over, but it can't, not without your help. But you're not helping. Why is that?

Love it, looking forward to the sequel that seems to keep the same look and feel.

(awkward reply to "why is that?" though)

way to dodge the question replicant!

Excellent post, with good informations and circumscribed.

Thanks for picking this one out, it looks perfect to have a tinker with whilst trying to diagnose my wifi issue here at home. I suspect I have a tonne of interference, but the HackRF route seemed a little over the top. This is much better!

Beware that depending on what kind of trouble you might have, the update rate of that analyzer might be several orders of magnitude too slow.

Interference is likely nowadays, with wifi in every apartment and everywhere, but one thing to consider is if you have any really old equipment on your wifi? If you have eg an 802.11b thing on the network, the router (perhaps the other devices too) downgrade to 802.11b too, to have a common denominator.

Interesting to hear your results, please do share later!

I have a nice project idea: build a replacement for HP's iLO (integrated lights out) system. Basically, all it needs to do is provide remote power and reset buttons for a server. An advanced version could also provide a remote keyboard, mouse, video, and port for an USB stick. The main reason why I'd want this is because HP's support system is a mess, iLO is expensive, and restricted to HP servers.

I think it could be done with a Raspberry Pi, and hopefully with minimal soldering inside the server itself.

https://www.kickstarter.com/projects/658903329/remoteboot-wi...

https://www.crowdsupply.com/ben-wang/remoteboot

I've created a successful Kickstarter project doing exactly this ;)

Uses a ESP8266 chip and has the basic version of what you described

That's nice.

However, I'd need it to be open-source, because connecting it to a HP Proliant server is probably not trivial (these beasts have two power supplies). Also, I need it to work over ethernet.

Not Ethernet but open-source: https://github.com/festlv/esp-power-control

The minimal version doesn't even require a CPU. All you'd need is a way to tap the audio from a phone and a DTMF decoder, a couple of latches for the PIN and two 5V reed relays to activate the buttons. If you want to do it using a CPU you could probably get by with a PIC chip, a simple AD converter and the two reed relays.

A Raspberry Pi would be so overpowered it is almost comical, but then again, for the money it is still a great solution.

Can't you do this with the notorious Intel ME?

My understanding is that Intel ME has security issues.

IPMI implementations also have issues.

Ideas have little value.

Execution beats talking about ideas for sure, but having ideas beats having nothing at all.

True, they make you feel good.

every valuable project starts with an idea though.

So does every worthless project. Valuable projects always have some initial action taken to make the idea a reality.

Initial action, like sharing the idea with a knowledgeable community in an appropriate moment (like here, now), to gather feedback on both usefulness to other people and viability of the proposed path of execution.

Talk is cheap, executing is valuable/hard/scary.

Before investing in execution, why wouldn't you weight it up with cheap talk? You think people should dive into execution straight away without forethought?

I would? I never said not to do that. I'm agreeing with GP that ideas are not very valuable.

Ok, so all projects start with an idea. What is your point then?

All idle dreaming starts with an idea too.

That it's easy to have an idea, and I wouldn't count it as when I started a project.

The post you originally responded to didn't seem to "count" anything, so what is your point in mentioning this? It was a idea with not much worth, as yet, but your own response has as little worth, but less potential.

It seems you just negged them for no reason.

Your post?

> every valuable project starts with an idea though

It's a tautology which adds nothing to the understanding of the reader: of course every valuable project starts with an idea, just like every great human being started with an ejaculation. I wouldn't let someone use that fact to justify cranking their hog, much less telling me all about it.

I apologise for making you feel like I was attacking that post for no reason. I intended to point out that I thought it was an empty statement which brought me no insight or enlightenment and didn't help me change my mind on the worth of ideas (in a vacuum).

Just keep discussing ideas, exploring and sharing them, working through the feedback etc.

Good luck!

And for those wanting to use small AVR processor modules without the Arduino IDE and libraries, here's some information. Those modules cost less than €2 on Ebay, just search for "attiny85 module"

http://blog.ithasu.org/2014/12/blinking-a-digispark-without-...

A heads up for these, the ATtiny is a different family than the ATmega's in the Arduino Uno. They are not 100% compatible, and if you are a beginner that can be problematic. Also the Tiny85 in particular that these modules use expose very few pins (5 usable).

That said, I use the Tiny85 all the time as they require minimal external components, so they are good to drop into a design for taking care of functions like interfacing peripherals or simple logic. For people just starting out though I'd recommend a Nano clone, they can be had for about the same price.

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