unwiredben

Just a reminder to you all that we've got some great classes coming up at NYC Resistor.

First, this Saturday, Raphael is teaching about the wonders of the Joule Thief!  It's a class about how to pull every bit of current possible out of little batteries. If you want to run something for a long time, check this out.  Details at http://joulethief.eventbrite.com/.

On Sunday, Liz and Ryan are leading an Arduino workshop where you get to solder up a Freeduino kit and then make it do amazing things.  If you want to get your hands dirty, this is the class to take.  There are just a few slots left for this one. http://arduino101.eventbrite.com/

On Sunday, November the 8th, Chris is teaching "CPUs 0b1100101: Intro to computer processors".  We've been talking about it here on the list -- it's all about computer architecture and how those chips that power your computers and devices work. http://cpus.eventbrite.com/

I'm very excited about the Build Your Own Retrocomputer class on November 12th.  Vince Briel is coming in from afar to lead a session where you can build one of his kits, including the Replica 1, a clone of the original Apple I.  It's way cooler than having an iPhone. There also will be a bit of an intro on the Parallax Propeller chip that's used in both the PockeTerm and Replica 1 included.  Details at http://retrocomputer.eventbrite.com/.

Finally, I'm teaching my popular Webduino class again on November 22nd, just before Thanksgiving.  Won't time with your family go even faster when you've got an Arduino acting as a webserver in your home? Come to the class and find out how you can make it happen.  It's online at http://webduino.eventbrite.com/.

These classes are fun, and they help keep NYC Resistor alive and in our great space in downtown Brooklyn.  Come down and learn.

This sign was made of five surplus LED boards, each one with shift registers to run the rows and separate driver pins for the columns (I could have that backwards). A small PC handled sending the bitmap data to the Arduino over the USB/serial connection, and it would then push out the data to the shift registers, scanning through all the columns. Multiple columns weren't active at the same time, but it scanned so quickly it looked very solid.

A few weeks ago, I sent off the 1.3 version of my RGB LED Shield to get fabbed. It was waiting for me when I returned from the Mozilla All-Hands meeting in California, but when I'd put it all together, it didn't work. I started checking soldering joints and electrical connections and discovered the problem; two rows of pins were swapped in my board layout, so it wasn't connecting the right pins to the Arduino. Because of the way that the TLC5490 pins are connected to special timer outputs, I couldn't fix this in software. I tried to see if I could reroute the signals on the board, but it didn't seem possible, However, I was able to verify that if I connected the board up with wires to the right pins, it did work.

Fast forward a couple of weeks. I'd gotten in a little board called the Stickduino. It's a small Arduino-compatible board that is about the size of a Flash drive. One end is a USB port, although it's not quite thick enough to make good contact in my laptop. I fix that with a couple of pieces of cardboard and a glue stick. I uploaded my arrows sketch to the board, then wired it up to the 1.3 RGB shield. The solid core wire was stiff enough to hold things in place, and it worked when I plugged it into my laptop.

To power this, I got out a $5 USB power supply I'd picked up on my California trip. It's not the most reliable gadget, but it's small, and if you aim the USB port to the ceiling, it will hold up the whole contraption. The picture is from it running in my bathroom. I've also got a YouTube video of it running it's very bright pattern below.

I'd probably not use this as a real nightlight, but as a quick light show at a party, I'm all over it. I also now have something to do with the rest of my v1.3 boards.

Here's one with a color box pattern that I wrote:

This was taken Sunday night over at Eric's place. The patterns you see going up/down from the LEDs are artifacts from the CCD sensor; you don't see them with your eyes. I think I'll do another video of the patterns bouncing off a wall to give a more ambient experience.

I got my first PC board back from Seeed Studios on Saturday; they arrived mid-week, but since they shipped from China, I had to go to the Post Office to retrieve them and sign the customs form. The box had a variety of parts including a big bag of tiny switches, and it had the five PC boards. I put my own board together that afternoon and tested it, but the real fun was earlier tonight when we got three more of the boards populated and flashing lights. Eric Moore got his waves test pattern running in a spiral configuration, and it looks really nice, especially bounced off a dark ceiling or wall.

There's more pictures at Flickr, and I should soon have the website at http://combee.net/rgbshield populated with part lists and assembly instructions. I've got a few tweaks to make for a version 1.2 of the shield based on our experiences putting these together, but nothing that should be too difficult to setup.

I've been working on a pretty nice chunk of code for the class I'm teaching later today. The main idea of the class is to put a web server on an Arduino board. Once you've got that, you can use any computer with a browser to pull data from the board or send commands to control things. As I worked on the code, I realized that a little refactoring would turn it into a nice framework for building lots of different webby things.

If you're interested, the project is hosted at http://webduino.googlecode.com. I'm releasing it with a MIT-style license. I expect to do a few more modifications to it over the next few days, especially after feedback I get from the class. I'll also probably restructure it to fit into the library scheme used for Arduino add-ons; right now, you just put a copy of the header into the folder with your code, which is nice for keeping it with your sketch, but not-so-nice for code duplication.

These are two little figures I made from spare parts I'd scavenged from a broken Atari 2600 video game console and a probably-working-but-useless Atari XM301 300-baud modem. They're held together with hot glue, and each one has a small magnet on its back so they can watch the kitchen from the freezer section of the refrigerator.

My first one is sitting at Annelies' desk; it stands upright with resistor legs embedded in a small piece of antistatic foam. I don't have a picture of that one yet.

I was inspired by the Maker Shed Store's Capacitor Robot Charms, but they're my own take on the idea.

BTW, if you're up here in New York and want to learn about making embedded devices that act like web servers, I'm teaching a two hour class on the subject on March 28th at NYC Resistor. After the class, I'll be putting my materials online, but I'm still working on everything right now.

You can get details on the class at http://www.eventbrite.com/event/302042417.

I recently installed a video mod board from the Longhorn Engineer into an Atari 2600. This gives the system real composite and s-video output ports, letting me bypass the RF modulator. The result is a much cleaner picture, especially with the s-video connection. If you're curious about how it went, you can check my comments on the AtariAge forums.

However, in attempting to install it in my first 2600, I think I fried something. I got no video signal at all or any signs of life on the audio jacks. Since I'd already clipped off resistors and removed the RF output on the board, I couldn't easily test it to see if it worked without the mod board soldered in, so I called it a loss. However, that left me with a mostly good 2600 motherboard.

Now, this isn't the original classic 2600 with four or six switches on the front, it's a "2600 Junior" that was introduced late in the system's life. The board has a 1983 copyright notice on it. However, that's still old enough that everything was soldered on as through-hole parts. Most modern devices use surface-mount parts that are much smaller and only connect to one side of a PC board. Back in the 1980's, surface mount technology hadn't taken over, so most parts were soldered to holes drilled in PC boards. In general, it's much easier to hand-assemble a through-hole design, but if you're doing automated assembly, surface mount works much better.

So, like any good electronics hobbyist, I didn't just throw away the dead 2600 motherboard. Instead, I got out my iron and my desoldering pump, and I started taking off components that might be useful in the future.

First to go was the 28-pin cartridge port. This is useful for modifying an Atari Flashback 2 console, one of those $30 plug-and-play game systems sold a few Christmases ago. The designer included pads on the PC board that you can wire to a real cartridge port to play old Atari games. I got a second unit at a Goodwill, so I'll probably try this modification soon.

Also useful were the many switches. There were switches for power, color selection, TV channel selection, and left and right difficulty. The power jack is a standard 1/8" headphone jack, so that's useful. I was also able to take off the two joystick ports; they're DB-9 connectors, but I'll probably use them to hook an old Atari joystick up to an Arduino.

I got a couple of potentiometers from the video circuit. These were used to adjust the color values at the factory. There was a big 5V power regulator chip that I could use in a future circuit. I was able to remove the power LED too, as it had long leads to be near the panel display hole.

What's left on the board is mostly not worth saving. There are about a hundred resistors, but the leads are clipped, so they would be hard to reuse. There are a few more ICs, but they aren't very useful outside of repairing other 2600s. I could save a few capacitors or transistors, but I'll probably just hold onto the board and just remove parts as I need them.