Hall Sensors Offer Drop-In Replacement For Drifting Game Console Joysticks

May 24, 2023 by Dan Maloney 46 Comments

No bananas were harmed in the making of this Hall effect drift-proof joystick replacement. OK, not really — two bananas were turned to mush. But it’s OK, they’re just bananas, after all.

Why bananas, you ask? Because [Marius Heier] uses them to demonstrate what we all intuitively know — that rubbing something over and over again tends to wear it away — but engineers seem to have forgotten. Wear such as this, with resistance material rather than fruits, is what causes the dreaded drift, a problem that the world collectively spends $20 billion a year dealing with, according to [Marius].

While numbers like that seem to be firmly in class-action lawsuit territory, sometimes it’s best to take matters into your own hands and not wait for the courts. The fix [Marius] shows here is to yank the potentiometers off a PS4 joystick and replace them with contactless Hall effect sensors. The end of the shaft for each axis gets a diametral neodymium magnet attached to it, while a 3D printed bracket holds a tiny custom PCB in close proximity. The PCB has an AS5600 Hall sensor, which translates the shaft angle to an analog voltage output. After programming the chip over its I2C bus, the sensor outputs a voltage proportional to the angle of each shaft, just like the original pots, but without all the wear and tear.

While [Marius] is selling these as drop-in replacements for PS4 controllers, he plans to release all the design files so you can build one yourself. He also has his sights set on replacements for PS5 and Xbox controllers, so watch for those. This isn’t his first foray into joystick hacking, having shared his 3D Hall effect and haptic feedback joysticks with us previously.

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Exploring The Hall Effect For Haptic Feedback PS4 Joysticks

January 26, 2023 by Dan Maloney 10 Comments

Modern gaming console controllers aren’t without their annoyances — Joy-Con drift, anyone? The problems might stem from design deficiencies, but we suspect that user enthusiasm and the mechanical stress it can introduce might play a significant role as well. Either way, [Marius Heier] decided to take a look at what would be required to build a better joystick and came up with some interesting results.

The first video below lays the basic groundwork, with a bunch of experiments with 3-axis Hall effect sensors, specifically the Texas Instruments TMAG5273 and TMAG5170. They’re essentially the same sensor with different interfaces — SPI for the 5170 and I2C for the 5273. Using just one of these sensors, he was able to build a joystick with the usual X- and Y- axis control, but also with a rotary axis. What’s more, he built a motorized version using two NEMA 17 steppers to mechanically drive the stick back to center.

The joystick is bulky, but it looks like he’s got plans for a much smaller one with [Carl Bugeja]-style PCB motors that should fit into a PS4 controller. That’s the subject of the second video below, which uses a different Hall sensor — an Allegro A1304 — and is mainly concerned with getting the output of a non-motorized but considerably miniaturized joystick stick talking the language that the controller expects. It’s not a simple process, but it seems to be coming along nicely, and we’ll be watching progress closely.

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Clever Mechanism Makes A Linear Control From A Rotary Hall Sensor

January 9, 2023 by Dan Maloney 81 Comments

Every once in a while we stumble across something so simple yet so clever that we just have to call it out. This custom linear Hall effect sensor is a perfect example of this.

By way of backstory, [Nixieguy], aka [The Electronic Mercenary], offers up a relatable tale — in the market for suitable hardware to make the game Star Citizen more enjoyable, and finding the current commercial joystick offerings somewhat wanting, he decided to roll his own controllers. This resulted in the need for a linear sensor 100 mm in length, the specs for which — absolute sensing, no brushes or encoders, easily sourced parts — precluded most of the available commercial options, like linear pots. What to do?

The solution [Nixieguy] settled on was to use a Hall effect sensor and a diametrally magnetized neodymium ring magnet. The magnet is rotated through 180 degrees by a twisted aluminum bar, which is supported in a frame by bearings. A low-friction slider with a slot captures the bar; moving the slider along the length of the control rotates the bar, which rotates the magnet, which allows the Hall sensor to measure the angle of the magnetic field. Genius!

The parts for the prototype sensor are all made from 0.8-mm aluminum sheet stock and bent to shape. The video below shows the action better than words can describe it, and judging by the oscilloscope trace, the output of the sensor is pretty smooth. There’s clearly a long way to go to tighten things up, but the basic mechanism looks like a clear win to us.

Hats off to [Nixieguy] for this one, which we’ll surely be following for more developments. In the meantime, if you need to brush up on the Hall effect, [Al Williams] did a nice piece on that a while back.

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The Seven-Segment Display That’s Also An Input Device

November 5, 2022 by Dan Maloney 1 Comment

We’re used to seeing all manner of seven-segment displays, be they mechanical, electronic, or something in between. But what all these displays have in common is that they’re, you know, displays. Using them as inputs would just be crazy talk, right?

Perhaps, but we like where [Dave Ehnebuske] is going with “InSlide,” the seven-segment input device. The idea for this comes from the “DigiTag” display, which we covered back in October, and divides a standard seven-segment character into three vertical strips — two skinny ones for the outside vertical segments, and one wide strip holding the horizontal elements. By sliding these strips up and down relative to each other, the standard nine digits, plus a few other characters, can be composed.

[Dave]’s take on this theme started by building his display from laser-cut plywood pieces, which is a nice choice because of the good contrast between the white wood and the engraver segments. Next, he embedded rare earth magnets in the slides and installed seven Hall effect sensors in the frame. The sensors are connected to an Arduino Nano via a 74HC165 parallel-load shift register, which lets multiple modules be daisy-chained together. He also built an Arduino library to read the current state of the segments; it supports the full hexadecimal character set, or even duodecimal if you like.

[Dave] has shared the library, and it looks like you can get the build files for the mechanism from the original project. That’s good, because this looks ripe for hacking. It looks like it would be pretty easy to motorize a display like this by adding rack-and-pinion gearing and steppers — something like that could make an interesting clock.

Mercury Thrusters: A Worldwide Disaster Averted Just In Time

April 18, 2022 by Lewin Day 60 Comments

The field of space vehicle design is obsessed with efficiency by necessity. The cost to do anything in space is astronomical, and also heavily tied to launch weight. Thus, any technology or technique that can bring those figures down is prime for exploitation.

In recent years, mercury thrusters promised to be one such technology. The only catch was the potentially-ruinous environmental cost. Today, we’ll look at the benefits of mercury thrusters, and how they came to be outlawed in short order.

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Hall Effect Module Knows Where Your Motor Is

April 12, 2022 by Al Williams 22 Comments

If you have a motor and you’d like to know where the shaft position is, you are likely to turn to an optical encoder scheme. However, as [lingib] points out, you can also use a magnet and a magnetometer. You can see how it works in the video below.

The MLX90393 is a 3-axis hall effect device and, with a magnet on the shaft, the X and Y outputs of the spinning magnet will form a quadrature output that you can easily read.

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One Stepper Plus A Whole Bunch Of Magnets Equals A Unique Seven-Segment Display

March 5, 2022 by Dan Maloney 24 Comments

Sometimes the cost of simplicity is extra complexity. It seems counterintuitive, but it seems to be true. And this single-motor mechanical seven-segment display seems to be a perfect example of this paradox.

On second thought, [aeropic]’s mechanism isn’t really all that mechanically complicated, but there sure was a lot of planning and ingenuity that went into it. The front has a 3D-printed bezel with the familiar segment cutouts, each of which is fitted with a pivoting segment, black on one side and white on the other.

Behind the bezel is a vertical shaft with three wheels, one behind each horizontal segment, and a pair of horizontal shafts, each with two wheels behind each vertical segment. The three shafts are geared to turn together by a single stepper in the base. Each wheel has ten magnets embedded in the outer circumference, with the polarity oriented to flip the segment in front of it to the right orientation for the current digit. It’s probably something that’s most easily understood by watching the video below.

We’ve seen quite a few of these mechanical seven-segment displays lately — this cam-and-servo mechanism comes to mind. We love them all, of course, but the great thing about [aeropic]’s display is how quiet it is — the stepper is mostly silent, and the segments make only a gentle clunk when they flip. It’s very satisfying.

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