Archive for October, 2012

Awesome quadcopter video

Ok, this article on quadcopter photography and video is definitely worth a look. There were a few quadcopters at the Maker Faire, complete with video payload being broadcast to a monitor. Ebsen Neilsen has taken it to the next level by flying the quadcopter with the video feed going directly to his goggles. You can even buy kits from Quadrocopter to get started, though the cost (~$3200 to start) will be a barrier to many (myself included). But building from an open hardware project like AeroQuad might be alot of fun. So many projects, so little time!

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October 20, 2012 at 3:27 pm Leave a comment

New Pi has arrived, now with moar memory!

I bought a backup Pi right after my first tests with the unit I bought at Maker Faire because I knew I was going to be playing with the GPIOs and interfacing with the real world, and equally sure that I’m going to blow it up eventually because I make some mistake with the wiring. So rather than living in fear, I simply accept it’s going to happen and plan for it. That means having a backup. So I ordered one from Element14 / Newark, and was pleasantly surprised a few days ago that the new units are shipping with double the memory (mentioned in an earlier post). The new Pi arrived yesterday and I printed a case on the 3D printer I have access to through work. The model STL file used to make the case was from Thingiverse, and it works pretty well, though I wish the area for the power connector would allow a deeper push into the seat… but that’s the beauty of having open hardware… I can modify the model to fix the issue :).

The new Raspberry Pi in a 3D printed case downloaded from Thingiverse.

Setting up the new unit was similar to the old one, with the exception of adjusting the firmware and boot process to accomodate the extra RAM. It took me a while to find a concise set of instructions for doing this, so here is what worked for me in the end:

    1. Install Hexxeh’s rpi-update utility, which grabs the firmware files and applies the updates (for the most part). The instructions at the Git-Hub site are easy to follow to install rpi-update.
    2. Run sudo rpi-update and follow the prompts.
    3. As of this writing, rpi-update does not take care of everything in the process, so edit /boot/config.txt and define how much memory the GPU should get by adding at the end: gpu_mem=128
    4. There are some other files that need to be copied to /boot, so use: cp /root/.rpi-firmware/* /boot
    5. Optional: clean up the /boot directory by removing the arm*_start.elf files, they are no longer needed.
    6. Reboot

Much of the above instructions were cobbled (pardon the pun) from the Raspberry Pi Community Projects web site. I can report that the Pi seems much faster with the extra RAM, especially on launching memory pigs like Chromium, which now pops up in a very reasonable amount of time (farewell Midori).

For now I’m going to leave the new Pi parked on the HDTV for the kids to play with.

October 20, 2012 at 3:08 pm Leave a comment

Working with the GPIO on Raspberry Pi

All sorts of goodies arrived in the last few days, so I spent some time tonight going through some online tutorials on how to work with the GPIO pins on the Pi, first directly through the linux virtual file system using shell scripts, and then moving on to python’s RPi.GPIO support. The first bit was done along the lines of Ch.8 in the early release of “Getting Started with the Raspberry Pi” (see “Untethered Pi” post for more on that), and that was a quick way to show how to read and write the GPIO pins. Eventually I got around to wiring up an ADC (MCP3008) following the tutorial provided by Adafruit (who sold me the chip and some other parts, and apparently supplied many of the parts in the Maker Shed Raspberry Pi Starter kit that I bought at Maker Faire, woot!).

The MCP3008 is a 10-bit ADC with 8 inputs and an SPI interface. One of the cool things I liked about the Adafruit tutorial is that they implemented an basic SPI control through the GPIO pins rather than using the on-board SPI interface, so you get to see the raw mechanics of how the clock signals are used to “bit bang” the information off the ADC. I cut out the audio-control aspect of the python code and just set it up to poll the ADC and print the value of the input if it changed by more than 5, since I was doing all this over VNC and thus no audio anyway. Their script polled every half second, but I cranked it up to poll every 0.1ms (10kHz) and the CPU was not totally pegged, so thats pretty neat. Of course, it’s not real-time, so when the OS preempts the process for other business, there can be a non-trivial pause. I’m sure it’s also happening at a low-level for tasks like communication over VNC and such. But it is still immensely satisfying to twist the potentiometer hooked to channel 0 and see the values go scrolling by in the terminal window.

According to FedEX tracking, my stepper drivers and motors arrive tomorrow, so that’s going to be tomorrow’s fun!

October 20, 2012 at 2:15 am Leave a comment

Untethered Pi

Reconfigured the Pi to stop booting into a LXDM desktop on the main display (HDMI) and instead create a VNC server with a default resolution matching my MacBook Pro so I could use that as my display when working on the Pi. As much as I like having a huge screen by using my HDTV, it just doesn’t cut it in clarity compared to my (non-Retina) display on my Mac. These eyes must be getting old or something. For setting up the vnc server, I basically just followed the directions here, with the user-specific startup script being used rather than the first one which runs as root (ugh!). Once that was working with Chicken of the VNC on my Mac, I used the raspi-config tool on the Pi to change the boot behavior to stop booting to a desktop. No need to squander precious memory running a desktop that I’m not looking at!

All this has a purpose of course, which is to allow me to disconnect the Pi from everything and move it to my worktable (see picture). Tomorrow I’ll solder the connector for the Pi-to-breadboard adapter that came with the Raspberry Pi Starter Kit that I bought at Maker Fair in NYC, then I can dig into Ch 8 of “Getting Started with the Raspberry Pi” that covers basic I/O. Access to the early release for the book is available both through the kit, and also through the Safari Books Online.

The Pi is on top of the Make: Electronics book, connected to my battery for portable power. Left is the iPad with Ch 8 of the “Getting Started with Raspberry Pi” on the Safari Books Online app, and right is the Mac running fullscreen VNC to the Pi.

October 18, 2012 at 2:21 am Leave a comment

Tiny houses taken to the limit?

This article from Dwell on the 1m^2 house is about an open-hardware project for what must be the ultimate limit to the tiny house movement. I’ve been fascinated by tiny houses and the associated movement since I stumbled across Tumbleweed Tiny House company. With our cluttered lives, there is something appealing about reducing your existence to something that fits in a very small footprint. Though I think 1m^2 is taking it a bit too far, it’s still an interesting concept. The article asserts that the design is already in use in parts of Europe, but I couldn’t find any references, and I’m having a hard time wrapping my head around someone living in it when winter comes. Still, the examination of space and stuff is worthwhile, even if a SQM of living space is not terribly practical.

October 16, 2012 at 1:41 am Leave a comment

Makerspaces

There’s a great post on the Make Magazine blog on the OpenROV success through Kickstarter and an associated discussion on makerspaces. Definitely worth the read, and of special interest is the information on the “How To Make a Makerspace Workshop”  being hosted by Artisan’s Asylum Feb 1st – 3rd 2013 for those interested in the establishment of new makerspaces. I’m very keen to get a makerspace going in the Capital District area of NY (Albany/Schenectady/Troy), so this seems like an excellent opportunity to get a ton of info on how others have done it so far. The only catch is that overlaps with Photonics West at the Moscone Center in San Franscisco (Feb 2 – 7th), and work comes before play… *sighs*. Need to find that two-places-at-once portal!

October 16, 2012 at 1:20 am Leave a comment

Double the memory on the Raspberry Pi

Some great news from the Raspberry Pi foundation and Newark / Element14 in my inbox today: my on-order backup Pi will have 512MB rather than the 256MB that my current model has. SWEET. It’s definitely the case that the performance of the system is limited by the memory, and doubling that is going to go a long way toward allowing more applications to work smoothly.

The official announcement is here. New Pi’s can be ordered from here. Definitely going to swap my current Pi out as “backup” and use the new one with the 384/128MB memory split.

October 16, 2012 at 12:55 am Leave a comment

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