Retrotechtacular: Principles Of Hydraulic Steering

December 30, 2014 by 27 Comments

Have you ever had the pleasure of trying to steer a one-ton pickup from the 1940s or wondered how hard it would be to turn your car without power-assisted steering? As military vehicles grew larger and heavier in WWII, the need arose for some kind of assistance in steering them. This 1955 US Army training film handily explains the principles of operation used in a hydraulically-assisted cam and lever steering system.

The basic steering assembly is described first. The driver turns the steering wheel which is attached to the steering shaft. This shaft terminates in the steering cam, which travels up or down along the camshaft depending on the direction steered. The camshaft connects to the steering shaft through a spline joint, which keeps the travel from extending to the steering wheel. The steering cam is connected to the Pitman arm lever and Pitman arm shaft. Movement is transferred to the Pitman arm, which connects to the steering linkage with a drag link.

The hydraulic system helps the Pitman arm drive the linkage that turns the wheels and changes the vehicle’s direction. The five components that comprise the hydraulic system use the power of differential pressure, which takes place inside the power cylinder. The hydraulic system begins and ends with a reservoir which houses the fluid. A pump driven by the engine sends pressurized fluid through a relief valve to the control valve, which is the heart of this system.

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[Sophi Kravitz] Joins The Hackaday Crew

December 30, 2014 by 32 Comments

Please join us in welcoming [Sophi Kravitz] to the Hackaday crew. She is coming on board to crank on the 2015 Hackaday Prize. You may remember a post from a few weeks ago when we were in search of a person with a skill set that could only be described as mythical. [Sophi] jumped at the chance and it is immediately clear that she belongs here.

[Sophi] walks the walk, and talks the talk. She’s an EE and has worked with art installations, built props and FX for movies, and tackled jobs that some might consider ‘more serious’ engineering challenges. Her passion for electronics has led her to evangelize education on the subject by working with student programs, and she recently served as a Hacker in Residence with Sparkfun. Her love of the hardware community already has her promoting hacking by immersing herself in Hackerspace culture and organizing events like the Bring a Hack meetup at Maker Faire New York.

We have big plans for the 2015 Hackaday Prize which will be announced soon. In the meantime, anyone attending the International Consumer Electronics Show (CES) next week can meet up with [Sophi] and find out about the plans we’ve made so far. She will be at CES to represent Hackaday along with [Mike Szczys] and [Sarah Petkus]. We’re planning an impromptu meetup for anyone interested. Reply to this Tweet to tell us you’ll be there and we’ll make sure to get you the details when we have them. And of course, if you want to get your hands on some Hackaday stickers track us down during the conference. Check out our CES Twitter list to make more connections.

Game Boy Cartridge Emulator Uses STM32

December 30, 2014 by 20 Comments

Game Boys may be old tech, but they still provide challenges to modern hackers. [Dhole] has come up with a cartridge emulator which uses an STMicroelectronics STM32F4 discovery board to do all the work. Until now, most flash cartridges used programmable logic devices, either CPLDs or FPGAs to handle the high-speed logic requirements. [Alex] proved that a microcontroller could emulate a cartridge by using an Arduino to display the “Nintendo” Game Boy boot logo. The Arduino wasn’t fast enough to actually handle high-speed accesses required for game play.

[Dhole] kicked the speed up by moving to the ARM Cortex-M4 based 168 MHz STM32F4. The F4’s  70 GPIO pins can run via internal peripherals at up to 100MHz, which is plenty to handle the 1MHz clock speed of the Game Boy’s bus. Logic levels are an issue, as the STM32 uses 3.3V logic while the Game Boy is a 5V device. Thankfully the STM32’s inputs are 5V tolerant, so things worked just fine.

Simple Game Boy cartridges like Tetris were able to directly map a ROM device into the Game Boys memory space. More complex titles used Memory Block Controller (MBC) chips to map sections of ROM and perform other duties. There were several MBC chips used for various titles, but [Dhole] can emulate MBC1, which is compatible with the largest code base.

One of the coolest tricks [Dhole] implemented was displaying a custom boot logo. The Game Boy used the “Nintendo” logo as a method of copyright protection. If a cartridge didn’t have the logo, the Game Boy wouldn’t run. The logo is actually read twice – once to check the copyright info, and once to display it on the screen. By telling the emulator to change the data available at those addresses after the first read, any graphic can be displayed.

If you’re wondering what a cartridge emulator would be useful for (other than pirating games), you should check out [Jeff Frohwein’s] Gameboy Dev page! [Jeff] has been involved in Game Boy development since the early days. There are literally decades of demos and homebrew games out there for the Game Boy and various derivatives. .

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Bringing A Legacy Pager Network Back To Life

December 30, 2014 by 24 Comments

[Jelmer] recently found his old pager in the middle of a move, and decided to fire it up to relive his fond memories of receiving a page. He soon discovered that the pager’s number was no longer active and the pager’s network was completely shut down. To bring his pager back to life, [Jelmer] built his own OpenWRT-based pager base station that emulates the POCSAG RF pager protocol.

[Jelmer] opened up his pager and started probing signals to determine what protocol the pager used. Soon he found the RF receiver and decoder IC which implements the POCSAG pager protocol. [Jelmer] began going through the sparse POCSAG documentation and assembled enough information to implement the protocol himself.

[Jelmer] used a HLK-RM04 WiFi router module for the brains of his build, which talks to an ATMega that controls a SI4432 RF transceiver. The router runs OpenWRT and generates POCSAG control signals that are transmitted by the SI4432 IC. [Jelmer] successfully used this setup to send control signals to several pagers he had on hand, and plans on using the setup to send customizable alerts in the future. [Jelmer] does note that operating this device may be illegal in many countries, so as always, check local frequency allocations and laws before tackling this project. Check out the video after the break where a pager is initialized by [Jelmer]’s transmitter.

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Z80, CP/M, And FAT File Formats

December 30, 2014 by 18 Comments

[Gary Kildall] and CP/M are the great ‘also ran’ of the computing world; CP/M could run on thousands of different 1980s computers, and [Gary] saw a few million in revenue each year thanks to CP/M’s popularity. Microsoft, DOS, and circumstances have relegated [Kildall] and CP/M to a rather long footnote in the history of microcomputers, but that doesn’t mean CP/M is completely dead yet. [Marcelo] wrote a Z80 emulator running CP/M inside an Arduino Due, and he did it in such a way that it’s actually convenient and useful to use.

Instead of using CP/M disk images, [Marcelo]’s emulator emulates CP/M disk drives on top of a regular FAT file system. Drives are mapped to folders in the FAT file system, so a folder named ‘A’ will show up as the A: disk in CP/M. Drives up to P: are supported, the maximum number of drives available under CP/M. The BIOS resides in the root directory of the SD card, and so far Microsoft Basic, Turbo Pascal, UCD Micromumps, and Wordstar work just fine.

The Arduino project was built upon one of [Marcelo]’s earlier projects that put the CP/M emulator on Windows. The version for the Due works exactly how you think it would, with a serial connection and terminal emulator providing the IO, and the huge amount of processing power and RAM available on the Due doing all the heavy lifting.

Reading Power Use Data With A Webcam And Python

December 29, 2014 by 5 Comments

As any hacker will attest to, whenever an important tool is missing, you might as well just build a new one! That’s the position that [Matt] found himself in when he was attempting to measure the power consumption at his parents’ house. He left the transmitter for the power meter at home, and so the logical thing to do was to set up a webcam and a python script to monitor his dad’s power meter instead of going back to get his.

The power meter that he had handy was a GEO Minim Electricity Monitor. He found it very difficult to extract the data directly from this particular meter, so instead of digging into any of the communications protocols int he meter, he set up a webcam in a box with an LED and monitored it with a specially-written Python script. The script is able to see the particulars of the meter, and then reports back to the computer with all of the relevant data. [Matt] has put this code up on his project site for anyone to use.

This is a great workaround that doesn’t involve delving too deep into the inner workings of the meter in question. You could always build your own power monitoring system though, if that’s more of your style!

Bike Rim Lighting Lets The Night Crowd Know When You’re Rollin’

December 29, 2014 by 8 Comments

There comes a wonderful “MacGyver moment” in many hackers’ lives when we find ourselves with just the right microcosm of scrap parts to build something awesome. That’s exactly what [dragonator] did with his gifted tech box from Instructables. He’s combined RGB LEDs, a Trinket, and a hall effect sensor to add a semicircular rainbow pattern to his night ride while he rides it.

The theory behind the hack is well-known: given the time between pings from a hall-effect sensor responding to the magnet on a bike wheel, an embedded system can estimate the wheel rpm and predict the time to display a particular color on the LEDs. [dragonator] uses the known wheel speed to determine the LED pattern currently on display: either a slow breathing pulse to a half-circle rainbow that displays on the lower bike rim. He drops in the needed equations and required components to follow his trail in a well-documented instructable.

Persistence of Vision (POV) is a nice extension from blinking your first (or first hundred) LED(s). It’s just enough math to get the casual onlooker to cry “magic” and just enough embedded electronics to get those seasoned double-Es to nod their heads. If you’re new to the POV crowd, [dragonator’s] Instructable may be a great start.

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