Maker Barn Organizer Creates Makerspace Access Control System

December 13, 2015 by Rud Merriam 15 Comments

The MakerBarn is a new makerspace between The Woodlands and Tomball, TX (north of Houston). [George Carlson], one of the founders and a retired design engineer, wanted to make sure only members certified on a machine could use it. He worked with [Kolja Windeler] to create the MACS or Makerspace Access Control System. He has one video explaining MACS and, after the break, another explaining the browser based user interface for the system.

A control box, [George] calls them stations, controls the power to a machine. Member badges have an RFID tag that is read when inserted into the station’s reader. If the member is authorized to use the machine, the power is enabled. For safety, the member’s badge must remain in the reader to maintain power. The reader uses a Photon board from Particle with a WiFi link to a Raspberry Pi server.

[Kolja] developed a Pi system to maintain a database of member numbers and the machines they can use. The list is sent to the stations periodically or when updates occur. The user interface is browser based on the MakerBarn’s LAN so it can be maintained by a computer or smartphone in the space. Presently 21 MACS modules have been built with some going to Hanover University in Germany for their auto hobby shop.

Not only did [George] lead the effort on creating MACS but has been key to getting the construction done inside a pole barn to make the MakerBarn a reality.

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Raspberry Pi Communication Via LASER

December 12, 2015 by Al Williams 28 Comments

[Nick Touran] wanted to make two Raspberry Pi’s communicate wirelessly. There are lots of options, but [Nick] used a LASER and a photoresistor, along with Morse code. If you don’t find Morse code fancy enough, you could always refer to it as OOK (on/off keying). The circuit uses a common LASER module and an ordinary photoresistor that varies in resistance based on light. A resistor forms a voltage divider with the photoresistor and an external A/D reads the resulting voltage.

The circuit works, but we couldn’t help but notice a few items. Not all photoresistors are as sensitive to the same light wavelengths, so for the maximum range you’d want to pick a particular photoresistor. While the analog to digital converter is certainly workable, we couldn’t help but wonder if you couldn’t set up the divider to use the inherent threshold of the Raspberry Pi’s input pins for a simpler circuit. Of course, if you used the same technique with an Arduino, you could use the built-in A/D converter, and the A/D converter is probably easier to get working.

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Solder More USB Ports To The Raspberry Pi Zero

December 12, 2015 by Brian Benchoff 58 Comments

Slowly, Raspberry Pi Zeros are falling into the hands of everyone who wants one. Quickly, though, it was realized that one USB port wasn’t enough, and having a single USB OTG port was only just the most economical solution. The Pi Zero does have a lot of test points exposed on the back, and [Peter van der Walt] is clever enough to come up with a 4-port hub you can solder directly to the Pi Zero.

[Peter] has a bit of experience with USB ports on the Pi, and the test points available on the bottom of this cheap and wonderful board provide everything you need to break out the single USB OTG port to a USB hub. We’ve seen this done before with a few tenuous solder connections between the Zero and an off-the-shelf USB hub. [Peter]’s build does it by soldering a USB hub directly to the Pi through these test points. It’s the first purpose built bit of hardware designed for the express purpose of giving the Pi four USB ports while only making it a sliver thicker.

The chip [Peter] is using for the build is the TI TUSB2046B, a device that turns a single USB port into a 4-port hub. This is a part that only costs about $2 in quantity, and the USB connectors themselves are only about $0.60 if you want to build a thousand of these solderable USB hubs. Now you see why the Pi Foundation didn’t include a whole host of ports on the Pi Zero, but it does mean you should be able to pick this board up for under $10 when it’s inevitably cloned in China.

[Peter] doesn’t have this board working yet. In fact, he’s only just sent the Gerbers off to the PCB fab. There will be an update once [Peter] gets the boards back and solders up the tiny but tolerable 0603 parts.

Which SD Card To Use In A Pi?

December 10, 2015 by Rud Merriam 51 Comments

There is surprising variation in the performance of SD cards. They are not all created equal and the differences can impact the running of your Raspberry Pi, no matter which model. [Jeff Geerling] wondered exactly how different cards would affect system performance. He ran a number of tests on cards ranging from cheap no-names to well-known brand names. The no-name cards fared pretty badly but even among the brand names there is considerable variation.

[Matt] over at Raspberry Pi Spy also tested SD cards and found similar differences. Both tested microSD cards. [Jeff’s] tests were solely on the Pi while [Matt’s] were on Windows 7, Ubuntu, and a Pi.

The discussions in the blog about what to measure were as interesting as the actual results. That lead to determining which software tools to use for the measurement. For example, a system doing a lot of small database reads and writes might work better with one SD card while a system storing and then streaming videos might work better with another card. Another interesting result is that the Pi’s data bus greatly limits the access speeds. [Jeff] measured much higher speeds running the same tests using a Mac with a USB dongle. The cards are capable of much more than the Pi can deliver.

[Matt] also checked the capacity of the SD cards. There are a lot of fakes floating around marked with higher capacities than they actually support. Even getting a brand name card may not help since some are counterfeit. So beware: if the price it too good to be true, it very well may be.

Audio Streaming On The Cheap With An RPi Zero

December 10, 2015 by Eric Evenchick 29 Comments

The minuscule size of the Raspberry Pi Zero makes it perfect for hacks where size is a factor. For example, a small, standalone device for getting streaming audio into your speakers. The RPi Zero doesn’t have an audio output on board, so PolyVection paired it up with their PlainDAC to build a minimal audio streaming device.

Their build uses a few lines from the GPIO header to drive an I2S digital to analog converter. The DAC is a PCM5142 from Texas Instruments that provides high quality sound output, and contains a built in programmable DSP.

The hardware fits into a 3D printed case, coming in at 68 mm by 48 mm. There’s no WiFi inside, but this can be added with an external USB device for wireless streaming. The DAC used is supported by the Linux kernel, so a simple configuration is all that’s needed to pipe audio out.

Once you have a device like this assembled, you can install a server like Music Player Daemon to remotely control the device and cue up internet radio channels.

Retro TV Breathes New Life With A Raspberry Pi

December 9, 2015 by James Hobson 33 Comments

There’s just something so satisfying about industrial design from the years past. [Kenneth] found an old “portable” tube TV and decided to give it a little upgrade so he could keep it around the house.

It was a black and white Singer TV, with a whopping 6″ tube display. Using his trusty screwdriver set he took the whole thing apart, keeping only the frame and outer casing. Inside he jammed a 5″ LCD display, a Raspberry Pi and a power supply — with some room to spare. He also replaced the speakers with some upgraded baby woofers and an audio amp for the Pi.

The end result is a pretty snazzy little device capable of playing movies, games, or hypothetically, even as an all-in-one computer — but who actually uses a Raspberry Pi as their daily driver? Especially one with only a 5″ display…

But it’s a cutie, and sits nicely on the coffee table. For a larger retro TV rework, we’re quite partial to this conversion of a Philco TV (a sub-brand of Phillips) with a flat panel LCD.

[via r/Raspberry_Pi]

Raspberry Pi $2 WiFi Through Epic SDIO Hack

December 9, 2015 by Elliot Williams 99 Comments

These are the times that we live in: the Raspberry Pi Zero comes out — a full freaking Linux computer on a chip for $5 — and people complain that it doesn’t have this or that. Top place on the list of desiderata is probably a tie between audio out and WiFi connectivity. USB is a solution for both of these, but with one USB port it’s going to be a scarce commodity, so any help is welcome.

Hackaday.io hacker [ajlitt] is looking for a way out of the WiFi bind. His solution? The Raspberry Pi series of chips has a special function on a bunch of the GPIO pins that make it easier to talk to SDIO devices. SDIO is an extension of the SPI-like protocol that’s used with SD memory cards. The idea with SDIO was that you could plug a GPS or something into your PDA’s SD card slot. We don’t have PDAs anymore, but the SDIO spec remains.

[ajlitt] dug up an SDIO driver for the ESP8089 chip, and found that you can liberate the ESP8266’s SPI bus by removing a flash memory chip that’s taking up the SPI lines. Connect the SPI lines on the ESP8266 to the SDIO lines on the Raspberry Pi, and the rest is taken care of by the drivers. “The rest”, by the way, includes bringing the ESP’s processor up, dumping new firmware into it over the SPI/SDIO lines to convince it to act as an SDIO WiFi adapter, and all the rest of the hardware communication stuff that drivers do.

The result is WiFi connectivity without USB, requiring only some reasonably fine-pitch soldering, and unlike this hack you don’t have to worry about USB bus contention. So now you can add a $2 WiFi board to you $5 computer and you’ve still got the USB free. It’s not as fast as a dedicated WiFi dongle, but it gets the job done. Take that, Hackaday’s own [Rud Merriam]!

Thanks [J0z0r] for the tip!