16-Bit Audio Output Via Voltage Reference

[Bruce Land] switched his microprocessor programming class over from Atmel parts to Microchip’s PIC32 series, and that means that he’s got a slightly different set of peripherals to play with. One thing that both chips lack, however is a digital-to-analog converter (DAC). Or do they? (Dun-dun-dun-duuuuhnnnn!)

The PIC part has a programmable, sixteen-level voltage reference. And what is a Vref if not a calibrated DAC? With that in mind, [Bruce] took to documenting its performance and starting to push it far beyond the manufacturer’s intentions. Turns out that the Vref has around 200 kHz of bandwidth. (Who would update a voltage reference 200,000 times per second?)

Anyway, [Bruce] being [Bruce], he noticed that the bits weren’t changing very often in anything more than the least significant bit: audio waveforms, sampled fast enough, are fairly continuous. This suggests using a differential PCM encoding, which knocks the bitrate down by 50% and saves a lot on storage. (Links to all the code for this experiment is inline with his writeup.)

The audio hacks that come out of [Bruce]’s Cornell ECE classes are always a treat. From the lock that you have to sing to open, to chiptunes programmed into an FPGA, there’s something for music fans of all inclinations.

AVR vs PIC, Round 223: Fight!

Get ready to rumble! [Thierry] made the exact same Hello-World-esque project with two microcontrollers (that are now technically produced by the same firm!) to see how the experience went.

It’s not just an LED-blinker, though. He added in a light-detection function so that it only switches on at night. It uses the Forest Mims trick of reverse-biasing the LED and waiting for it to discharge its internal capacitance. The point is, however, that it gives the chip something to do instead of simply sleeping.

Although he’s an AVR user by habit, [Thierry] finds in favor of the PIC because it’s got a lower power draw both when idling and when awake and doing some computation. This is largely because the PIC has an onboard low-power oscillator that lets it limp along at 32 kHz, but also because the chip has a lower power consumption in general. In the end, it’s probably a 10% advantage to the PIC on power.

If you’re competent with one of the two chips, but not the other, his two versions of the same code would be a great way to start familiarizing yourself with the other. We really like his isDarkerThan() function which makes extensive use of sleep modes on both chips during the LED’s discharge period. And honestly, at this level the code for the two is more similar than different.

(Oh, and did you notice [Thierry]’s use of a paper clip as a coin-cell holder? It’s a hack!)

Surprisingly, we’ve managed to avoid taking a stray bullet from the crossfire that occasionally breaks out between the PIC and AVR fans. We have covered a “shootout” before, and PIC won that round too, although it was similarly close. Will the Microchip purchase of Atmel calm the flames? Let’s find out in the comment section. We have our popcorn ready!

Camera Slider Helps get the Shots with E-Waste Controller

A camera slider is an accessory that can really make a shot. But when your business is photography rather than building camera accessories, quick-and-dirty solutions often have to suffice. Thus the genesis of this camera slider controller.

The photographer in question in [Paulo Renato], and while his passion may be photography, he seems to have a flair for motorized dollies and sliders. This controller is a variable-speed, reversible, PIC-based design that drives an eBay gearmotor. The circuit lives on a scrap of perfboard, and it along with batteries and a buck converter are stuffed into the case-modded remains of an old KVM switch. Push buttons salvaged from another bit of e-waste act as limit switches, and a little code provides the magic. We like the hacked nature of the controller, but we wonder about the wisdom of using the former KVM’s USB ports to connect the controller to the drivetrain; it’s all fun and games until you plug a real USB device into it. In sum, though, a nice build with nice results. Check out his other videos for more on the mechanicals.

Camera slider rigs aplenty have graced our pages, including one made mostly of wood and one controlled by a fancy iPad app.

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ChaiBot: A Tea Robot Steeped in Utility

On the surface, a cup of tea is a simple thing to make. Heat up some water, insert tea leaves, and wait for it to steep. The wait time is a matter of taste, and it is absolutely crucial to remove the bag or infuser before it’s too late. Otherwise, you end up with a liquid that’s almost, but not quite, entirely unlike tea.

[Adrian] and his son would often find themselves lost in conversation during the steeping process and let it go too long. But that was before they built ChaiBot, an automatic tea minder. This fine-looking machine uses an old CD drive to raise and lower the tea bags, which are held by a thin piece of stainless steel mesh. Once the bags are lowered, [Adrian] pours hot water into the cups. The weight of the water is detected by a capacitive sensor under the cup cutouts, and this triggers the timer to start counting down to the perfect cuppa.

One of the coolest features of ChaiBot is the built-in circulation. Every minute, the bags are lifted out briefly and reinserted, disturbing the water so the steeping is more uniform. Since the final step to making great tea is drinking it before it goes cold, ChaiBot sends a push notification to [Adrian]’s phone. Be sure to check out the demo after the break.

Here’s another CD drive-based tea bot we covered a while back. It’s not quite as pretty, but it gets the job done. If you’re not one to wander off while your tea steeps but prefer not to watch a clock, here’s a compact timer that’ll fit in your pocket.

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Hack the Hackaday Demoscene from Your Own Home

We are just two weeks away from the Hackaday | Belgrade conference, and tickets have completely sold out. That means you can’t get your hands on one of these sweet hardware badges, but you can still take home some prizes for pulling off a gnarly hack with the badge firmware.

What we’re talking about is the Hackaday Belgrade Badge Demoscene – which includes a surrogate presenter program for anyone who wants to send in their own code for the device. You have two weeks to work on and submit your code — and we’ve made it really easy for anyone who has a working knowledge of C.

The day of the conference we will download all entries, and have a surrogate at the conference load it onto their badge and present it on your behalf. There is a separate pool of prizes for online entries, so hackers not at the con will win. And of course we’ll be celebrating the awesome demos with some posts on the front page.

No Hardware Needed

Badge emulator scrolling the word "Hackaday"
Badge emulator scrolling the word “Hackaday”

Hack in C for Abstracted Bliss or Be Hardcore:

You can use the emulator shown here to write your code for this badge. It comes with a set of basic functions that abstracts away the low-level hardware functions, and launches a demo window on your computer to test out your code. Check out this barebones C framework to get started.

For those that want more control, we have published the official assembly code that the badges will ship with (including a user manual). We’ll be squashing bugs right up to the day of the con). You can alter and compile this code yourself, or just start from scratch using the design spec if you prefer to travel the hardcore bit-monkey path.

Either way, you have an 8×16 display and 4 buttons to work with. Exercise your creativity and amaze us by doing a lot on a rather modest canvas. That’s what demoscene is all about.

How to Enter

Entry is easy, just start a project on Hackaday.io and submit it to the Belgrade Badge Demoscene contest using the “Submit Project To…” menu on your project page. You need to upload .C and .H files, or a precompiled .HEX to the file hosting part of your project page by Saturday, April 9th.

That’s the extent of the requirements. But it would be super fun if you recorded the software emulator playing your demo for all to see. The easiest way to do this is to record a video of your computer screen using your smartphone. Good luck to all!

Adorable Matchbox Robot

[wattnotions] has been playing with matches, well the box they come in anyway. One day he was letting synapses fire unsupervised, and wondered if he could build a robot inside of a matchbox. His first prototype was a coin lithium battery and scrounged motors from those 3 US Dollar servos you can buy by the dozen. It scooted around just fine, but it drained the battery instantly and was a little boring.

Next, he etched a board. It had a little PIC micro, a connector for a mini LiPo, and an H bridge. It fired up just fine, and even though it drained the battery way too fast, at least it wasn’t brainless anymore. In our experience, robots tend to discard all the useful data they collect anyway, so being blind wasn’t too much of a problem.

Inspired and encouraged, with synapses gloriously undeterred, [wattnotions] set out to make a version 2. This time he ordered a board from OSHPark, made a 3D model in SketchUp, and proceeded to lock himself out from his own chip. Without a high voltage programmerhe was out of luck. The development was unfortunately put on hold.

It was fun to read along with [wattnotions] as he went on a small robot adventure. We hope he’ll complete a version 3 and have a swarm of the little fellows scooting around.

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Microchip To Acquire Atmel for $3.56 Billion

Just last week, there was considerable speculation that Microchip would buy Atmel. The deal wasn’t done, and there was precedent that this deal wouldn’t happen – earlier this year, Dialog made an approach at Atmel. Now, though, the deal is done: Microchip will acquire Atmel for $3.56 Billion.

There are three main companies out there making microcontrollers that are neither ancient 8051 clones or ARM devices: TI’s MSP430 series, Microchip and Atmel. Microchip has the very, very popular PIC series microcontrollers, which can be found in everything. Atmel’s portfolio includes the AVR line of microcontrollers, which are also found in everything. From phones to computers to toasters, there’s a very high probablitiy you’re going to find something produced by either Atmel or Microchip somewhere within 15 feet of your person right now.

For the hobbyist electronic enthusiast, this has led to the closest thing we have to a holy war. Atmel chips were a little easier (and cheaper) to program, but were a little more expensive. Microchip’s chips have a very long history and proportionally more proper engineers who are advocates. PIC isn’t Arduino, though, a community that has built a large and widely used code base around the AVR family.

Microchip’s acquisition of Atmel follows several mergers and acquisitions in recent months: NXP and Freescale, Intel and Altera, Avago and Broadcom, and On Semiconductor and Fairchild. The semiconductor industry has cash and wants to spend it. What this means for the Atmel product line is left to be seen. The most popular micros probably won’t be discontinued, but if you’re using unpopular Atmel micros such as the ATtiny10 you might want to grab a reel or two before they’re EOL’d.