You’ve Never See A Solid-State Oscilloscope Like This One

August 25, 2018 by Jenny List 44 Comments

Remember a the time before oscilloscopes had a brain? It’s easy to forget as we’ve become accustomed to a class of simple solid state oscilloscope using a microcontroller as signal processor and a small LCD display to show the resulting waveforms. They are commonly available as inexpensive kits, and while their bandwidth is not huge they give a good account of themselves in low frequency applications. But of course, originally the signal processing was handled in a much simpler way.

[SimpleTronic] reminds us that a small solid state oscilloscope does not need a microcontroller, with a ‘scope on a breadboard that displays waveforms on an LED matrix in a much more traditional manner. This is very much an analogue oscilloscope, in which the X deflection circuitry of the CRT is replaced by a decade counter stepping through the columns of LEDs on the display, and the Y deflection circuitry by some analogue signal conditioning followed by an LM3914 bar graph display chip driving the display rows. There are a few refinements such as a trigger circuit, but it remains a very understandable and surprisingly simple device.

It has a claimed bandwidth of 40 kHz defined by its sweep ranges rather than its analogue bandwidth, and an input voltage range from 50 mVpp to 50 Vpp. It’s hardly a useful instrument due to its low bandwidth, but its strength lies in novelty and in understanding a traditional oscilloscope rather than in its utility. You can see it in action in the video we’ve placed below the break.

‘Scopes of limited use appear from time to time on these pages. A favourite of ours is this soldering iron.

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Retro-uC, Your Favorite Instruction Sets On Custom Silicon

August 23, 2018 by Brian Benchoff 29 Comments

A few months ago, we caught wind of an interesting project in Big-O Open silicon. It’s a chip, loaded up with the great CPU cores of yore. Now, it’s finally a project on Crowd Supply. The Retro-uC project is an Open Source microcontroller for the retro geek, with a Zilog Z80, MOS 6502, and Motorola 68000 buried in the epoxy of a single QFP package. Oh yes, custom silicon and retro goodness, what more could you want?

The Retro-uC project is part of the Chips4Makers project to develop an Open Source chip for the community. Of course, this has been done before with projects like the HiFive1 and other RISC-V implementations, but really — this is a Z80, 6502 and 68k on a single chip. Let’s not bury the lede here.

As far as the architecture and implementation of these cores go, the ‘active’ core is externally selected on reset, or can be changed through the JTAG interface. There are 72 GPIO pins that can handle 5V, with each pin mapped to the address space of the cores. So far, so good. We can make this work for some really cool stuff.

The JTAG interface is used for testing and programming, although programs can be stored on an external I2C Flash chip and booted from there. There is 4kB of on-chip RAM, and while the peripheral configuration is still being determined, there will at least be UART, I2C, and PWM peripherals. How many of each is anyone’s guess.

The Retro-uC is now a Crowd Supply project, with rewards/orders/whatever ranging from a bare Retro-uC chip for $42 USD to an Arduino Mega-ish development platform for $89, a breadboard version of the chip for $59, and a chip mounted to a Perf2+ prototyping board for $65.

While this chip hasn’t even gotten to tape-out, all the cores work on an FPGA, and there is precedent for doing Open Source, crowdfunded silicon. We’re looking at this one closely and are excited to see what everyone is going to make.

This project has been a long time in the making, with the project lead giving a talk at FOSDEM earlier this year. Now it’s finally time for the hard part of any silicon project — getting the money — and we’re looking forward to see what comes of it.

FCC Filing Reveals Tasty Hardware McSecrets

August 22, 2018 by Tom Nardi 121 Comments

If you’ve visited a McDonald’s recently, you might have noticed something of a tonal shift. Rather than relying on angsty human teenagers to take customer orders, an increasing number of McDonald’s locations are now using self-serve kiosks. You walk up, enter your order on a giant touch screen, and then take an electronic marker with you to an open table. In mere minutes your tray of ~~nutritious~~ ~~delicious~~ cheap food is brought to you by… well that’s still probably going to be an angsty teenager.

Thanks to a recent FCC filing pointed out to us by an anonymous tipster, we now know what kind of tech Ronald has packed into the electronic table markers (referred to as “tents” in McDonald’s parlance). It turns out they are Bluetooth Low Energy beacons powered by the Nordic nRF52832 chipset, and include some unexpected features such as an accelerometer to detect falls.

The Nordic nRF52832 features a 32-bit ARM Cortex M4F processor at 64 MHz with 512 KB flash and 64 KB SRAM. Quite a bit of punch for a table marker. Incidentally, this is the same chip used in the Adafruit Feather nRF52 Pro, so there’s already an easily obtainable development toolchain.

A image of the backside of the PCB shows a wealth of labeled test points, and we imagine figuring out how to get one of these table markers doing your own bidding wouldn’t be too difficult. Not that we condone you swiping one of these things along with your Quarter Pounder with Cheese. Though we are curious to know just why they need so much hardware to indicate which table to take a particular order to; it seems the number printed on the body of the device would be enough to do that.

This isn’t the first time we’ve taken a peek behind the Golden Arches. From reverse engineering their famous fries to hacking the toys they give out with Happy Meals, there’s more to do at the local McDonald’s than get thrown out of the ball pit again.

Badgelife, The Hardware Demoscene Documentary

August 20, 2018 by Brian Benchoff 19 Comments

Last week, tens of thousands of people headed home from Vegas, fresh out of this year’s DEF CON. This was a great year for DEF CON, especially when it comes to hardware. This was the year independent badges took over, thanks to a small community of people dedicated to creating small-run hardware, puzzles, and PCB art for thousands of conference-goers. This is badgelife, a demoscene of hardware, and this is just the beginning. It’s only going to get bigger from here on out.

We were lucky enough to sit down with a few of the creators behind the badges of this year’s DEF CON and the interviews were fantastic. Right here is a lesson on electronic design, manufacturing, and logistics. If you’ve ever wanted to be an engineer that ships a product instead of a lowly maker that ships a product, this is the greatest classroom in the world.

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How The 8087 Coprocessor Got Its Bias

August 18, 2018 by Steven Dufresne 8 Comments

Most of us have been there. You build a device but realize you need two or more voltages. You could hook up multiple power supplies but that can be inconvenient and just not elegant. Alternatively, you can do something in the device itself to create the extra voltages starting with just one. When [Ken Shirriff] decapped an 8087 coprocessor to begin exploring it, he found it had that very problem. It needed: +5 V, a ground, and an additional -5 V.

His exploration starts with a smoking gun. After decapping the chip and counting out all the bond wires going to the various pads, he saw there was one too many. It wasn’t hard to see that the extra wire went to the chip’s substrate itself. This was for providing a negative bias to the substrate, something done in some high-performance chips to get increased speed, a more predictable transistor threshold voltage, and to reduce leakage current. Examining where the bond wire went to in the circuitry he found the two charge pump circuits shown in the banner image. Those worked in alternating fashion to supply a -5 V bias to the substrate, or rather around -3 V when you take into account voltage drops. Of course, he also explains the circuits and dives in deeper, including showing how the oscillations are provided to make the charge pumps work.

If this is anything like [Ken’s] previous explorations, it’ll be the first of a series of posts exploring the 8087. At least that’s what we hope given how he’d previously delighted us with a reverse engineering of the 76477 sound effects chip used in Space Invaders and then went deeper to talk about integrated injection logic (I²L) as used in parts of the chip.

Multi-switch Useless Box Is Useless In Multiple Ways

August 17, 2018 by Richard Baguley 11 Comments

We’ve probably all seen (and built) a useless box, in which you flip a switch that activates a servo that pops out a finger and flips the switch off. [Coffeman500] decided to take this a step further by building a useless box with multiple switches. Flip one, the finger pops out to flip it back. Flip several switches, and the finger pops out and flips each back in turn.

It’s a smart build that [coffeeman500] says is his first electronics build. The compulsively switching brain of this is an ATmega328 driving an A4988 stepper motor driver, with one stepper moving the finger mechanism and the other moving the finger along a rail to reach each switch in turn. [Coffeeman500] has released the complete plans for this wonderful waste of time, including 3D models for the box and mechanism, plus the code. Redditors are already planning bigger and more useless designs with more switches, a pursuit that we fully support.

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Arcade Inspired Halloween Candy Dispenser

August 15, 2018 by Tom Nardi 3 Comments

The days are getting shorter and the nights are a little cooler, which can only mean one thing: it’s officially time to start devising the trials you’ll put the neighborhood children through this Halloween. For [Randall Hendricks], that means building a new candy dispensing machine to make sure the kids have to work for their sugary reward. After all, where’s the challenge in just walking up and taking some candy from a bowl? These kids need to build character.

[Randall] writes in to share his early work on this year’s candy contraption which he’s based on a popular arcade game called “Goal Line Rush”. In this skill based game a disc with various prizes spins slowly inside the machine, and the player has a button that will extend an arm from the rear of the disc. The trick is getting the timing right to push the prize off the disc and into the chute. Replace the prizes with some empty calorie balls of high fructose corn syrup, and you get the idea.

There’s still plenty of time before All Hallows’ Eve, so the machine is understandably still a bit rough. He hasn’t started the enclosure yet, and at this point is still finalizing the mechanics. But this early peek looks very promising, and in the video after the break you can see how the machine doles out the goodies.

The disc is rotated by a high torque motor, and the aluminum extrusion arm is actuated with a gear motor and custom chain drive. Some 3D printed hardware, a couple limit switches, and a pair of relays make for a fairly straightforward way of pushing the rod out when the player presses the button on the front of the cabinet.

Considering how his previous Mario-themed candy dispenser came out, we doubt this new machine will fail to impress come October. The neighborhood kids should just count themselves lucky he’s not using his creativity to terrorize them instead.

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