Automatic Arduino Bicycle Shifter

September 4, 2020 by Danie Conradie 16 Comments

One of the keys to efficient cycling performance is a consistent pedalling cadence. To achieve this the cyclist must always be in the correct gear, which can be tricky when your legs are burning and you’re sucking air. To aid in this task, [Jan Oelbrandt] created Shift4Me, an open-source Arduino powered electronic shifter.

The system consists of a hall effect sensor at the pedals to measure cadence, an Arduino controller, and a servo mechanism to replace the manual shifter. Everything is mounted in a small enclosure on the frame. The only way to get one is to build your own, so a forum is available for Shift4Me builders, where the BOM, instructions, code and other documentation is available for download. Most bikes should be easy to convert, and [Jan] invites builders to post their modifications and improvements.

Since the only input is the cadence sensor, we wonder if the system will interfere more than help when the rider has to break cadence. It does however include allowance to hold on the current gear, or reset to a starting gear by pushing a button. One major downside is that you will be stuck in a single gear if the battery dies since the manual shifter is completely removed.

As one of the oldest continuously used forms of mechanical transport, there is no shortage of bicycle-related hacks. Some of the more recent ones we’ve seen on Hackaday include e-bike with a washing machine motor, and a beautifully engineered steam-powered bicycle.

An Arduino Controller For Hot Air Handles

September 4, 2020 by Tom Nardi 3 Comments

In general, the cost of electronic components and the tools used to fiddle with them have been dropping steadily over the last decade or so. But there will always be bargain-hunting hackers who are looking to get things even cheaper. Case in point, hot air rework stations. You can pick up one of the common 858D stations for as little as $40 USD, but that didn’t keep [MakerBR] from creating an Arduino controller that can be used with its spare handles.

Now to be fair, it doesn’t sound like price was the only factor here. After all, a spare 858D handle costs about half as much as the whole station, so there’s not a lot of room for improvement cost-wise. Rather, [MakerBR] says the Arduino version is designed to be more efficient and reliable than the stock hardware.

The seven wires in the handle connector have already been mapped out by previous efforts, though [MakerBR] does go over the need to verify everything matches the provided circuit diagrams as some vendors might have fiddled with the pinout. All the real magic happens in the handle itself, the controller just needs to keep an eye on the various sensors and provide the fan and heating element with appropriate control signals. An Arduino Pro Mini is more than up to the task, and a custom PCB makes for a fairly neat installation.

This isn’t the first time we’ve seen somebody replace the controller on one of these entry-level hot air stations, but because there are so many different versions floating around, you should do some careful research before cracking yours open and performing a brain transplant.

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3D-Printed Flight Controls Use Magnets For Enhanced Flight Simulator 2020 Experience

September 3, 2020 by Donald Papp 23 Comments

We have seen quite a few DIY joystick designs that use Hall effect sensors, but [Akaki Kuumeri]’s controller designs (YouTube video, embedded below) really make the most of 3D printing to avoid the need for any other type of fabrication. He’s been busy using them to enhance his Microsoft Flight Simulator 2020 experience, and shares not just his joystick design, but makes it a three-pack with designs for throttle and pedals as well.

Hall effect sensors output a voltage that varies in proportion to the presence of a magnetic field, which is typically provided by a nearby magnet. By mounting sensors and magnets in a way that varies the distance between them depending on how a control is moved, position can be sensed and communicated to a host computer.

In [Akaki]’s case, that communication is done with an Arduino Pro Micro (with ATmega32U4) whose built-in USB support allows it to be configured and recognized as a USB input device. The rest is just tweaking the physical layouts and getting spring or elastic tension right. You can see it all work in the video below.

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Over-Engineered Single Button Timer

August 28, 2020 by Bryan Cockfield 13 Comments

Feature creep is typically something to be avoided, since watching a relatively simple project balloon into a rat’s nest of complexity often leads to ineffective, or even abandoned, projects. On the other hand, if you can maintain a tight focus, it’s not always a bad thing. [cbm80Amiga] shows us how to drill down and add specific features in this single-button timer without losing focus on what the original project was all about.

The timer is based on an Arduino Pro Mini and an HX1230 LCD with a simple piezo speaker for audible alerts. A single button controls operation of the timer, with short presses incrementing each digit and long presses moving on to the next digit. Controlling button presses this finely is a project in its own, but then [cbm80Amiga] moves on to other features such as backlight control, low power modes which allow it to operate for around two years on a single battery charge, preset times for various kitchen uses, and different appearance settings.

Honestly we aren’t sure how you could cram any more features on this timer without fundamentally altering the designed simplicity. It doesn’t fall into the abyss of feature creep while being packed with features, and it’s another example of how keeping things simple is often a recipe for success.

Thanks to [Hari] for the tip!

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New Arduino JPEG Library Focuses On Speed

August 26, 2020 by Lewin Day 10 Comments

Working with graphics on microcontrollers has always meant focusing on making the most of limited resources. Particularly in the 8-bit era, all manner of tricks were used to get low-performance chips to achieve feats beyond their lowly station. However, these days, we’re blessed with 32-bit workhorses with clock speeds in the tens, or even hundreds, of MHz and many kilobytes of RAM to match. It’s these higher performance chips [Larry] had in mind when writing his JPEGDEC library.

As [Larry] discusses in a blog post on the topic, JPEG libraries already exist for the Arduino platform. However, many of these are aimed at 8-bit platforms with tiny amounts of RAM. While it’s possible to decode JPEGs piece by piece with some intelligent code under these conditions, it’s possible to go much faster when you’ve got a little more headroom. [Larry] does a great job of explaining the variety of optimizations he’s developed in the two decades since writing his first JPEG decoder back in 1994. From eliminating unnecessary marker checks to ignoring unneeded data for scaled-down output, it all adds up to get the job done faster. The library targets the Cortex-M0+, or any chip with a minimum of 20K of RAM, as its bare minimum to operate. Faster chips with higher clock rates naturally do better, and [Larry] provides benchmark decoding times for various common hardware using the library.

We’ve featured [Larry]’s GIF decoder for the Arduino platform before, again a useful library that’s optimised for good performance. If you’ve got your own neat tricks for image processing on microcontrollers, you know how to call!

Sunrise, Sunset, Repeat

August 25, 2020 by Kristina Panos 5 Comments

Sunrises and sunsets hardly ever disappoint. Still, it’s difficult to justify waking up early enough to catch one, or to stop what you’re doing in the evening just to watch the dying light. If there’s one good thing about CCTV cameras, it’s that some of them are positioned to catch a lovely view of one of the two, and a great many of them aren’t locked down at all.

[Dries Depoorter] found a way to use some of the many unsecured CCTV cameras around the world for a beautiful reason: to constantly show the sun rising and setting. Here’s how it works: a pair of Raspberry Pi 3B + boards pull the video feeds and display the sunrise/sunset location and the local time on VFD displays using an Arduino Nano Every. There isn’t a whole lot of detail here, but you can probably get the gist from the high-quality pictures.

If you wanted to recreate this for yourself, we might know where you can find some nice CCTV camera candidates. Just look through this dystopian peephole.

Thanks for the tip, [Luke]!

Facing The Coronavirus

August 22, 2020 by Brian McEvoy 1 Comment

Some of us are oblivious to how often we touch our faces. The current finding is we reach for our eyes, nose, or mouth every three to four minutes. Twenty times per hour is an awful lot of poking, picking, itching, and prodding when we’re supposed to keep our hands away from glands that can transmit and receive disease. To curb this habit and enter the 2020 Hackaday Prize, [Lloyd lobo] built a proof-of-concept device that sounds the alarm when you reach for your face.

We see an Arduino Uno connected to the classic HC-SR04 ultrasonic distance sensor, an LED, and we have to assume a USB battery pack. [Lloyd] recommends the smaller Nano, we might reach for the postage-stamp models and swap the ultrasonic module out for the much smaller laser time of flight sensor. At its soul, this is an intruder alarm. Instead of keeping siblings out of your room, you will be keeping your hands out of the area below the bill of the hat where the sensor is mounted. If you regularly lift a coffee cup to your lips, it might chastise you, and if you chew sunflower seeds, you might establish a tempo. *crunch* *chip* *beep* *crunch* *chip* *beep*

We have reviewed technology to improve our habits like a bracelet that keeps a tally, and maybe there is a book that will help shirk some suboptimal behaviors.

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