How To Use Lidar With The Raspberry Pi

January 22, 2016 by Rud Merriam 29 Comments

The ability to inexpensively but accurately measure distance between an autonomous vehicle or robot and nearby objects is a challenging problem for hackers. Knowing the distance is key to obstacle avoidance. Running into something with a small robot may be a trivial problem but could be deadly with a big one like an autonomous vehicle.

My interest in distance measurement for obstacle avoidance stems from my entry in the 2013 NASA Sample Return Robot (SRR) Competition. I used a web camera for vision processing and attempted various visual techniques for making measurements, without a lot of success. At the competition, two entrants used scanning lidars which piqued my interest in them.

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Cleanest Rasberry Pi NES Mod

January 20, 2016 by Elliot Williams 18 Comments

[ModPurist] sent us his Raspberry-Pi-in-a-Nintendo casemod. Before you go hitting the back button, this is a good one because it’s so well executed. And it’s actually a two-fer: he’d previously built up a wireless NES controller that completes the setup.

Both of these mods are hacks in the purest sense of the word. The controller mod took a wireless keyboard’s sending circuit board and wedged it inside the NES controller. The original NES controller reads out the buttons into a shift register and sends that down a wire. That’s all gone. [ModPurist] just wired up each button to the sender PCB and figured out which keys they corresponded to on the PC by pressing the buttons. Simple.

The best part of his video about building the controller? After about a minute in, he forgets that he’s filming a technical how-to video and plays Pokemon for the remaining four minutes. That’s the sign of success.

Then there’s the NES hack itself. He stripped everything out, added a Raspberry Pi 2 and a fan, made it all work with the power switch and the original TV outs, and it’s done. Again, nothing more than needs doing, but nothing less. It looks just right plugged up to the CRT monitor (from a C64, no less), and there’s no doubt that being able to play wirelessly on an original NES controller is cool.

This isn’t [ModPurist]’s first time here on Hackaday either, and his “Cold Boy” fridge-turned-Gameboy is a work of art.

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Pi Zero Video Card Via Bare Metal Programming

January 17, 2016 by Brandon Dunson 10 Comments

Rolling your own synthesizer is no small feat, which is what [Thomas] has taken on with his project “Nerdsynth”. [Thomas] has an impressive amount of data on his site covering the overall design and progress of the project, but that isn’t what piqued our interest. [Thomas] has an on-board TFT display to navigate the versatile Nerdsynth’s menu but he wanted to add video output to do some video sequencing. After some investigation and poking around the available options he decided to tackle yet another sub-project (textbook scope-creep).

[Thomas] chose to do to some bare metal programming on the Pi Zero to use it as a video card for video output. By following a tutorial from Valvers and modifying an SPI driver from Microelecroniki he was able to clone the video on an external monitor. This is a step in the right direction and we’ll have to keep an eye on his site for updates about video sequencing on the external display.

You can check out a recent demo of the Nerdsynth in action after the break, sadly you’ll have to settle for a pic of the cloned screen (below) until [Thomas] posts another update.

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Raspberry Pi Wind Measurement

January 16, 2016 by Rud Merriam 18 Comments

A well organized approach to a project is a delight to see. [Pavel Gesyuk] takes just that approach with the experiments on his blog. Experiment 13 is a multi-part series using a Raspberry Pi as the heart of a weather station. [Pavel] is looking at wind speed and direction, and temperature measurement, plus solar power for the station. One of his videos, there are many, is after the break.

The anemometer and direction sensors are stock units wired to a Raspberry Pi A+ using an analog to digital daughter board. The data from the temperature sensor is acquired using I2C. During one part of the experiment he uses an EDIMAX WiFi adapter for collecting the data.

Python is [Pavel’s’ language of choice for development and freely shares his code for others to see. The code collects the data and displays it on a monitor connected to the Pi. The experiment also attempts to use solar power to charge batteries so the station is not dependent on mains power.

The mechanical assembly shows attention to detail commensurate with his project presentation and we respect how well organized the work is.

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Smart Mirror Notices You And Turns On

January 14, 2016 by James Hobson 22 Comments

Smart, technology filled bathrooms are inevitably coming, but until then, be the first in your group of friends to make your very own smart mirror!

Gaining popularity in recent months, it’s not that difficult to make a smart mirror. In fact, it’s really just an LCD monitor with a one-way mirror slapped on top. Similar to how Infinity Mirrors work.

The build makes use of an older LCD monitor [Tmonaco189] had laying about. He went to the hardware store and picked up some wood to build a frame that would fit the aspect ratio of the monitor perfectly — and of course to be large enough to cover up the rear casing of the monitor. Once built, it was time to make it smart! Continue reading “Smart Mirror Notices You And Turns On” →

My Payphone Runs Linux

January 14, 2016 by Anool Mahidharia 28 Comments

For the 20th anniversary of the Movie “Hackers” [Jamie Zawinski], owner of DNA Lounge in San Francisco, threw an epic party – screening the movie, setting up skating ramps and all that jazz. One of the props he put up was an old payphone, but he didn’t have time to bring it alive. The one thing he didn’t want this phone to do was to be able to make calls. A couple of weeks later, he threw another party, this time screening “Tank Girl” instead. For this gathering he had enough time to put a Linux computer inside the old payphone. When the handset is picked up, it “dials” a number which brings up a voice mail system that announces the schedule of events and other interactive stuff. As usual, this project looked simple enough to start with, but turned out way more complicated than he anticipated. Thankfully for us, he broke down his build in to bite sized chunks to make it easy for us to follow what he did.

This build is a thing of beauty, so let’s drill down into what the project involved:

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PS/2 Keyboard For Raspberry Pi

January 14, 2016 by Al Williams 29 Comments

A lot of people can bake a cake. Sort of. Most of us can bake a cake if we have a cake mix. Making a cake from scratch is a different proposition. Sure, you know it is possible, but in real life, most of us just get a box of cake mix. The Raspberry Pi isn’t a cake (or even a pie), but you could make the same observation about it. You know the Raspberry Pi is just an ARM computer, you could program it without running an available operating system, but realistically you won’t. This is what makes it fun to watch those that are taking on this challenge.

[Deater] is writing his own Pi operating system and he faced a daunting problem: keyboard input. Usually, you plug a USB keyboard into the Pi (or a hub connected to the Pi). But this only works because of the Linux USB stack and drivers exist. That’s a lot of code to get working just to get simple keyboard input working for testing and debugging. That’s why [Deater] created a PS/2 keyboard interface for the Pi.

Even if you aren’t writing your own OS, you might find it useful to use a PS/2 keyboard to free up a USB port, or maybe you want to connect that beautiful Model-M keyboard without a USB adapter. The PS/2 keyboard uses a relatively simple clock and data protocol that is well-understood. The only real issue is converting the 5V PS/2 signals to 3.3V for the Pi (and vice versa, of course).

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