Yes, you can control simple bare-bones LCD displays using just an Arduino. No
driver boards or additional chips are required. If you have controlled a
7-segment LED display directly from an Arduino, you can do the same with an
LCD.
However, there are a few tricks to doing it correctly. It's easy really. But I was trying to do it with mystery, undocumented displays. As you might guess, much fun and hilarity ensued.
This LCD is being controlled with just an Arduino. There are no additional chips or driver boards, just the bare LCD and an Arduino. The LCD was scavenged from an old CD player. It has a 7-segment display as well as icons and animations. Using salvaged LCD screens can lead to all sorts of surprises. This tiny display, with only nine pins, is actually quite complex to control. It has multiple layers of displays that are controlled by changing which pin you use as the common pin.
Why a Bare LCD
I have plenty of working LCD displays in all sizes and types. They are easy to
hook up and simple to control with an Arduino. Why would I want to use a bare
LCD instead?
Well, because I have them and because I didn't know how to use them. It was a
challenge.
Over the years I have scavenged a large collection of LCD displays out of
broken electronic devices. They still worked when I salvaged them, but I had
no idea how to
SUCCESS !!! - well sort of. I can now make an LRA vibrator click and pop and hum - very weakly, but it's definitely progress.
Recently, I posted about finding (I thought) a mythical LRA vibration motor. After spending the last few hours combing through the 62 page spec-sheet for the DRV2605L Haptic Motor Driver Chip from Texas Instruments, I'm almost certain it really is an LRA vibrator.
I'm using the Adafruit Haptic Motor controller board for the chip, so I'm also using Adafruit's library. Sparkfun also sells the same type of board along with a library. Both manufacturers have an excellent, easy-to-use implementation for driving standard ERM vibrators (lots of fun). And both have a function for sending audio signals, like music or voice, to an LRA. However, neither has a good example for the command set for LRAs.
Hooking up the LRA (or an ERM) vibration motor is easy thanks to Adafruit's DRV2605L Haptic motor controller board. Even a classic Arduino is capable of handling it because all the calculations are handled by the chip. Just send a code over the I2C line and the waveform is executed. Tuning an LRA, now that's a lot more complicated.
Now I understand why, and it's not the fault of Adafruit or Sparkfun - the LRAs themselves are picky and tricky and each one is unique. The driver chip needs a lot of info about the physical operation of the LRA. There are lots of register bits to set and obscure mathematical formulas to deal with before the LRA resonates properly.
Although both libraries give you easy access to these register values, it doesn't do me much good because I don't have enough info about this specific LRA so I don't know what values that motor needs in those slots. Properly tuning the resonance for these motors seems more like a job for a skilled luthier, not an electronics hobbyist.
Nevertheless, I bravely went into the core CPP and H files (a scary thing for me) and set the hex values for some registry slots (according to page 15 of the manual). And what do you know - it works. The LRA moves and every one of the waveforms is distinct. Short or sharp or ramped or rumbling, they are all very distinct. But I have to have my finger touching the vibrator to feel them. When the vibe was still in a phone it would rattle my knee caps. So I'm still doing something wrong.
Compare this to using an ERM. The simple ERM just slings an off-balance weight around a shaft. It's easy to configure and the pulse is powerful. But the waveforms feel almost the same. Out of about 100 different waveforms, I can sense maybe five different feelings. The rotating mass just doesn't stop or start quickly enough, so the difference between a short pulse and a long one is negligible. A double or triple pulse feels like single pulse because the mass is still moving when the next pulse hits.
There may be ways to brake the ERM quicker, I'll explore more and report back. I know when I was making a haptic gaming chair I would hit the rumble-motors with a quick reverse or braking command to create a much sharper and stronger sensation. There could be commands for ERMs in these libraries that I just don't know about yet.
If I can find a well documented LRA cheaply enough I might get one or two. Until then I'll play with this scavenged one and randomly change values. I'm not the only one struggling with this issue of LRAs, so there are some good forum posts about it. But this whole process reminds me of the bad old days when electronics were obscure and difficult and confusing.
On a positive note, if the corporate "they" see enough of us playing with this (spending money) one of them will make us a nicely documented, simple to use LRA so we'll all buy them. Just sayin...
Just published a short tutorial on Instructables about using salvaged parts and e-waste to make jewelry. You've seen some of the projects here on the blog, but I go into more depth about the process and techniques used.
It's also the first time I reference my previous work. In this tutorial I point back to one of the simple tear-down videos. I've spent several months making a series of very basic how-to videos and tutorials. I now have a set of foundational guides I can refer back to. That way, I don't have to make every tutorial really long and detailed. I can just point back to one of the foundation series.
Check it out and let me know what you think (or any of my Instructables). I feel the need to go do some coding and welding now, so this might be the last jewelry based post for a few months. The 3d printer is also sitting in the corner taunting me for not playing with it for at least a month.
I've also got plans for more projects that use all the items from the foundation series. Drop me a note if you've seen any ideas proposed in the basic guides that you want to see turned into actual projects.
Then again, I might 3d print some jewelry to weld, so.....
Create poetry with up-cycled T-shirt scraps. Turn your old tees into one-of-a-kind works of individualized art.
Someone donated a bunch of old T-shirts for my (failed) attempt at making 3d printed templates. So I found myself with lot's of tees that didn't fit me/ I slashed a few in my experiments, but I still had lots left over/
I figured I could make a few hoods and scarves and pillows. But what could I do with all those free swag tee shirts from 2014? Too bad I couldn't just use elements from each of the designs and make something new.
Or wait... maybe I could. I do have scissors and I do have fabric glue. Heck, I even own a sewing machine if I wanted to get serious.
So I sat down with the scissors and a bag of old shirts during the Olympics and started cutting out words from the front and back of 20 shirts.
It was a perfect task. Unlike most of my hobbies I could start and stop with no ill effects. I didn't lose my train of thought, the tee didn't dry, crack, sag or over-process in any way.
I enjoyed the parts of the Olympics I wanted and the holes in the tee shirts stayed just as they were and when I came back I just started cutting again.
What I thought would be a tedious task turned out to be a lot of fun. In fact, I think it helped me enjoy the Olympic events even more.
Nervous about whether your fave is going to make it into semi-finals - well cut apart some tee shirts.
Your favorite might be getting knocked off the podium - make the cuts extra ragged. Heck the more ragged and nervous looking the better, just makes it look really hand made.
Of course making the scraps into a work of art is another story. Once I realized that I could never color coordinate or match sizes or fonts - well then it became fun again and I had some flashbacks to my teen tears and rebellious designing. Shew, this adulting in design thing had messed with my sense of freedom and spontaneity.
So this was a good, I got a sense of fun back, made something fun from discarded clothes, and even found a bright-sided silvered-lining to the filed craft-knife experiments. This was a fun win.
Of course my short poem writing skills had also atrophied. But I listened to some music, realized the lyrics actually made no sense and if they could do it then I could do it, I composed three amaze-balls poems in just a few minutes. And I think I got back with my teen self here as well.
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What's inside an old ultrasonic humidifier, and is there anything worth salvaging? The short answer is YES, lot's of fun stuff in there.
Someone donated this old ultrasonic humidifier for us to tear down. I hoped we could get the speed control and maybe a fan out if it. But I didn't know if everything would be on a single PCB and therefore difficult to salvage. Luckily, all the main components were separate and the PCB only supplied the power.
So we wound up getting a bunch of good components that we can re-use. We also got some nifty tidbits that will be good for prop building. Check out the short video to see what we found...
It looks like the humidifier had gotten hit with a power surge. But this thing was sturdy and it still sort of worked, if very weakly. There was almost no mist or air coming out of it. Once we cracked the case we could see why. The surge had run in and fried the AC components. It's surprising that it still worked at all, but it made it easy for us to decide to salvage it instead of repairing it.
We tested the salvaged components and they all worked fine. My two favorites are:
An all-in-one power switch with speed control and LED indicator complete with housing
Both of these still worked perfectly. We also got some nice heat-sinks, some JST connectors, a small cage fan and several oddly shaped items perfect for use in cosplay or prop building,
Knob and Controls
The speed control is perfect for an Arduino project. It has three completely separate circuits going into the same housing to control three functions. There's a high current circuit to the on/off switch, a mid current to potentiometer, and a light-duty circuit to the LED.
I also noticed that they were using the potentiometer more like what I think as a rheostat. Even though the potentiometer has three tabs, they were only using two. But the tabs are accessible, so we can always add the traditional third line of the circuit.
With this configuration, you can turn the project on, then control an analog input with a single knob. The LED can be pulsed or blinked to give visual feedback.
And it's in a great housing that's really easy to mount into any project. It's circular and flat, so no weird shapes and curves to match. Just cut a hole, a big hole, into any enclosure and you have a very nice control panel - sweet!
Water Level Sensor
My other favorite find was the magnetic reed switch and magnet combo. This sensor is already on a slim PCB with a handy JST connector. And the floating ring-magnet is already sized to trigger the switch.
That's going to make using this as a water level sensor so much easier. These sensors and magnets are cheap to buy, but configuring them can be a hassle. When they come pre-matched and sold for use in fountains the price goes way up. So to get these for free was a pleasant surprise.
Overall, I'm very happy with the haul from this old humidifier. And the video was fun to make so I might start recording more teardowns. We have a room full of donated items, a huge random collection of semi-junk to tear apart and explore - loads of fun for the whole family - and much better than experimenting with items that still work.
