Raspberry Pi

1836 Articles

A Pi Robot Without A Hat

July 6, 2016 by 10 Comments

Daughter boards for microcontroller systems, whether they are shields, hats, feathers, capes, or whatever, are a convenient way to add sensors and controllers. Well, most of the time they are until challenges arise trying to stack multiple boards. Then you find the board you want to be mid-stack doesn’t have stackable headers, the top LCD board blocks the RF from a lower board, and extra headers are needed to provide clearance for the cabling to the servos, motors, and inputs. Then you find some boards try to use the pins for different purposes. Software gets into the act when support libraries want to use the same timer or other resources for different purposes. It can become a mess.

The alternative is to unstack the stack and use external boards. I took this approach in 2013 for a robotics competition. The computer on the robots was an ITX system which precluded using daughter boards, and USB ports were my interface of choice. I used a servo controller and two motor controllers from Pololu. They are still available and I’m using them on a rebuild, this time using the Raspberry Pi as the brain. USB isn’t the only option, though. A quick search found boards at Adafruit, Robotshop, and Sparkfun that use I2C.

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A 150MHz 6502 Co-Processor

July 5, 2016 by 16 Comments

If you are familiar with ARM processors, you may know of their early history at the 1980s British home computer manufacturer Acorn. The first physical ARM system was a plug-in co-processor development board for Acorn’s BBC Micro, the machine that could be found in nearly every UK school of the day.

For an 8-bit home computer the BBC Micro had an unusually high specification. It came with parallel, serial and analog ports, built-in networking using Acorn’s proprietary Econet system, and the co-processor interface used by that ARM board, the Tube. There were several commercial co-processors for the Tube, including ones with a 6502,  a Z80 allowing CP/M to be run, and an 80186.

As with most of the 8-bit generation of home computers the BBC Micro continues to maintain a strong enthusiast following who have not stopped extending its capabilities in all directions. The Tube has been interfaced to the Raspberry Pi, for instance, on which an emulation of original co-processor hardware can be run.

bbc-tube-screenshotAnd thus we come to the subject of this article, [Hoglet] and [BigEd]’s 150MHz 6502 coprocessor for the BBC Micro. Which of course isn’t a 6502 at all, but a 6502 emulated in assembler on an ARM which is in a way the very distant descendant of the machine it’s hosted upon. There is something gloriously circular about the whole project, particularly as the Pi, like Acorn, the BBC Micro, and modern-day ARM, has its roots in Cambridge. How useful it is depends on your need to run 8-bit 1980s software in a tearing hurry, but they do report it runs Elite, which if you were there at the time we’re sure you will agree is the most important application to get running on a BBC Micro.

We’ve featured the Tube interface before when we talked about an FPGA co-processor with a PDP/11 mode that was definitely never sold by Acorn. And we’ve also featured an effort to reverse engineer the primordial ARM from that first BBC Micro-based co-processor board.

BBC Micro image: Stuart Brady, Public Domain, via Wikimedia Commons.

Raspberry Pi Zero Becomes Mighty Miniature Minecraft Machine

July 2, 2016 by 21 Comments

In a clever bit of  miniaturization, [JediJeremy] has nearly completed a gyro-mouse controller for a Raspberry Pi Zero! Ultimately this will be a wearable Linux-watch but along the way he had some fun with the interface.

Using the MPU6040 gyroscope/accelerometer card from a quadcopter, [JediJeremy] spent a week writing the driver to allow it to function as a mouse. Strapping an Adafruit 1.5″ PAL/NTSC LCD screen and its driver board to the Zero with rubber bands makes this one of the smallest functional computer and screen combos we’ve seen. Simply tilt the whole thing about to direct the cursor.

It presently lacks any keyboard input, and [JediJeremy] has only added a single button for clicking, but look at this thing! It’s so tiny! In his own words: “I think this is the first computer that I can accidentally spill into my coffee, rather than vice versa.”

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Raspberry Pi Gets Turned On

June 28, 2016 by 27 Comments

The Raspberry Pi and other similar Linux-based single board computers simplify many projects. However, one issue with Linux is that it doesn’t like being turned off abruptly. Things have gotten better, and you can certainly configure things to minimize the risk, but–in general–shutting a Linux system down while it is running will eventually lead to file system corruption.

If your project has an interface, you can always provide a shutdown option, but that doesn’t help if your application is headless. You can provide a shutdown button, but that leaves the problem of turning the device back on.

[Ivan] solved this problem with–what else–an Arduino (see the video below). Simplistically, the Arduino reads a button and uses a FET to turn off the power to the Pi. The reason for the Arduino, is that the tiny processor (which draws less than a Pi and doesn’t mind being shut down abruptly) can log into the Pi and properly shut it down. The real advantage, though, is that you could use other Arduino inputs to determine when to turn the Pi on and off.

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Hackaday Prize Entry: A Raspberry Pi Project

June 23, 2016 by 40 Comments

There’s no piece of technology that has been more useful, more influential on the next generation of sysadmins and engineers, and more polarizing than the Raspberry Pi. For $35 (or just $5), you get a complete single board computer, capable of running Linux, and powerful enough to do useful work. For the 2016 Hackaday Prize, [Arsenijs] has created the perfect Raspberry Pi project. It’s everything you expect a Pi-powered project to be, and more.

While the Raspberry Pi, and the community surrounding the Raspberry Pi, get a lot of flak for the relatively simple approach to most projects which are effectively just casemods, critics of these projects forget the historical context of tiny personal computers. Back in the early ‘aughts, when Mini ITX motherboards were just being released, websites popped up that would feature Mini ITX casemods and nothing else. While computers stuffed into an NES, an old radio, or the AMD logo are rather banal projects today, I assure you they were just as pedestrian 15 years ago as well. Still, the creators of these Mini ITX case mods became the hardware hackers of today. It all started with simple builds, a Dremel, and some Bondo.

[Arsenijs] takes his Raspberry Pi project a bit further than a simple casemod, drawing influence from a Raspberry Pi smartphone, a Raspberry Pi security system, a Portable Raspberry Pi, and a Raspberry Pi wrist computer. These are all excellent projects in their own right, but [Arsenijs] is putting his own special twist on the project: he’s using a Raspberry Pi, and a few Raspberry Pi accessories.

While this project is first and foremost a Raspberry Pi project, [Arsenijs] isn’t limiting himself to the platform with the Broadcom chip. The team behind this Raspberry Pi project was busy porting the project to Odroid when the Banana Pi came out. This changed everything, a refactor was required, and then the Orange Pi was announced. Keeping up with technology is hard, and is a big factor in why this Raspberry Pi project hasn’t delivered yet. You can say a lot of things about the Raspberry Pi foundation, but at least their boards make a good attempt at forward compatibility.

Already [Arsenijs]’ Raspberry Pi project is one of the more popular projects on Hackaday.io, and is in the running for being one of the most popular projects in this year’s Hackaday Prize. Whether that popularity will translate into a minor win for this year’s Hackaday Prize remains to be seen, but it seems for [Arsenijs] that doesn’t matter; he’s already on the bleeding edge of Raspberry Pi projects.

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Ikea Projection Lamp Makeover Adds LED Matrix And Raspberry Pi Zero

June 14, 2016 by 39 Comments

If you’re like us, it’s hard to walk through an Ikea without mentally hacking everything there into something else. The salad bowl? Parabolic antenna. Drawer slides? Linear motion rails. Storage containers? Etching tank. We admit that we still haven’t figured out what to do with that 1,000-pack of tea lights.

[Alain Mauer] pulled off an Ikea hack that we’ve always dreamed about. In particular, he took the Sprida projector lamp and wedged an 8×8 LED matrix and Raspberry Pi Zero into it.

The lamp in question is essentially a slide projector for kids. Before [Alain] got to it, it had an LED in the back, a mount for a slide in the middle, and a focusing lens on the front. His mod is simplicity itself: remove the LED and transparency, and place the LED matrix in the focal plane where the slide used to be. Reverse images on the LED in software to compensate for the lens, and you’re done.

The video says “Raspberry Pi Zero with WiFi” and the project title promises “IoT”, but we don’t see the WiFi in the build. We’re guessing that [Alain] will get around to it — it’s easily doable. (Doh! There’s a tiny USB WiFi dongle providing the obligatory wireless connection.) Anyway, the point is the projection, and we love it, and we’d be lying if we said it didn’t make us think about RGB matrices.

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Pi Zero Digital Frame Kiosk Uses OTG Right

June 3, 2016 by 14 Comments

USB On-The-Go (OTG) is one of the fun aspects of the USB standard. There are feelings about the other aspects, but that one is alright. Regardless, [Francesco] realized one day that the £3 digital picture frames he purchased at a charity sale really didn’t care if the files on the thumb drive mysteriously changed all the time. It would just keep pulling and displaying the latest file at a blistering 0.2 frames per second. That’s right, the concept [Francesco] went after is to show changing data, even animations, with an update of one frame every five seconds!

raspberry-pi-zero-otg-picture-frame-weatherHis initial tests showed good for the concept — the Pi can easily emulate a mass storage device, feeding in data whenever the picture frame looks for it. In addition to the Pi Zero board he added an Ethernet shield, a voltage regulator, a camera, and even some infrared LEDS. We suppose there are dreams for the future.

He has been developing scripts for this rig by logging in through a VNC. A cron job runs his scripts at regular intervals, grabbing useful data and making it available as an image. For example, one script opens up the weather in Epiphany (a web browser), takes a screenshot, and saves that screenshot to the mass storage being emulated using USB OTG. The digital picture frame blissfully updates, unaware of its strange appendages. Now the real limiting factor is how much you can accomplish with your mad Bash skills.