scruffy days

We’ve renamed the project!

For Sunday 12/10:

- prep for Megan’s PcompNoComp presentation
- sketch out display/kiosk needs, email Rob

Stuffs we need:

Circuit Parts List:

1. 2 more Hitec HS-545BB servos (ordered from Chief Aircraft, should arrive Sat/Mon)
2. 2 more chokes (McMaster - Megan placed order today)
3. 8 more IN4002 diodes (I have IN4004 ones, but not sure if these will work the same? Gotta check datasheet)
4. 2 more TL082 op amps (samples from ST should arrive by Mon, 12/11)
5. 2 more arduinos/atmel chips - got these

Bellow, Etc. Parts List:

1. Wood for bellow bases, flowerbox, and individual flower bases?
2. 4 Kitchen hose sealer neck thingys
3. 2 T-shaped plumbing piece for mounting to servos
4. Dowels
5. Bases for mounting servos (should be same height as bellow base)
6. Aluminum flashing for top of bellow

TO DO:

1. Build circuits, get compact and see if possible to share power across 3 different circuits from one 12V DC Supply - otherwise, buy an additional (we have 2). But would be most efficient to run off one! Especially in our case.
2. Tighten up cord/choke design for presentation? Depends on visibility.
3. Test flower shape for most dramatic on/off states
4. Need weight to keep servo stationary - might just mean mounting it to one plank of wood holding together the bellow+arm+servo
5. “Business” cards from plastic bags
6. Post info to site before show

Gilad and I were able to successfully connect our voltage measuring circuit to Barbara (one of the batteries being charged by ITP’s solar panel mounted on the roof of the NYU Tisch building), but not before we fried 1 XBee Pro and a couple of PIC chips. sigh. That’s what happens when you’re excited about working with energy and electricity at 3 in the morning, I guess.

Will post code shortly - Gilad, Ilteris and I setup 3 boards, each with an XBee Pro radio. One circuit is placed on the 12th floor alongside the battery and leads from the solar panel which takes solar energy voltage readings. This is sent to a 2nd circuit around the 7th/8th floor, which relays that to a 3rd circuit on the ITP floor. This last circuit’s also got an XPort, which connects to a database and logs the voltage readings successfully - YAY!

Flickr set

rest in peace, little one…

To reconfigure new, replacement xbee pro:
ATID 8888 (set the PAN ID - more on that from Faludi)
ATMY2 (my address)
ATDL, ATDH (destination address hi/lo)

We’re in need of a slightly stronger servo for our Electric Garden bellow mechanism, so I’ve been digging around and learning a bit more about these puppies. A few local hobbyshops have snubbed me for calling them “servo motors” - ask for “servos”. At ITP, you’re introduced to working with these in this basic lab. The more torque you need, the pricier these get, so I figured it best to know a little about them before buying…

Here are a few resources I’ve been using:

• Hitec Servo basics - overview of materials used for gears, and motor types
• Hitec Servos, with links to manuals and spec sheets
• FAQs on servos by Hitec
• Hobbico Servos
• Joe from Precision R/C in Bensonhurst, Brooklyn was helpful in explaining the range of servos available, and their prices are pretty good in comparison to online shops
• Other online retailers: Acroname, Vex (pricey), Jameco (way pricey)

On figuring out the right servo for your application, Hitec says the following:

1. Servos are rated for Speed and Torque. In many cases, Hitec will create one servo and then gear it for speed and sacrifice torque, then create its twin, geared for torque at the sacrifice of speed, i.e. 525/545, 625/645, 925/945.
2. If you are not sure, it is better to have more torque than you need, as torque is your friend.
3. When in doubt ask your peers about servo application questions. Look at what others are using in comparable applications. Usually the kit manufacturer will suggest a servo of a certain physical size and torque value specification in the aircraft, car or boat plans. It is wise to follow their guidelines.
4. Digital servos provide instantaneous response, finer adjustments, more torque, but consume more power so best to run off NiMH batteries (vs. dry cell batteries)

XBee czar, Rob Faludi, led a workshop today on getting started with soldering, circuit setup and basic AT commands. Maxstream XBee radios are useful for “low-cost, low-power wireless sensor networks”.

Claim yer Personal Area Network numbers here (We’ll need this as a number of projects on the floor will be communicating via these puppies. Assigning these IDs to our networks will help avoid sending/reading other projects’ communication…oy vey, what a mess that would be).

Gilad and I read through most of the AT commands in the manual to get a grasp on some of the capabilities that would suit our Solar Panel datalogging application. Maxstream provides good documentation, and it’s pretty easy to read. Download the Product Manual (802.15.4) here.

Also searched support on Maxstream site “xbee network no microprocessor” - we figured we could use some of the built in features of the XBee to manage certain tasks, such as simple routing of data. The following article supports this “The XBee is capable of directly sending these DIO signals from one module to another without any additional hardware” - http://www.maxstream.net/support/knowledgebase/article.php?kb=188

In our case, we’ll have 3 XBees - one each on the 12th, 8th and 4th floors to send data from the solar panel. Our 8th floor XBee basically serves as a router to relay the data from the 12th Fl to 4th Fl circuit. Pseudocode = “Listen, and if you receive any data, send it. Then resume listening.”

We tried to enable both Digital I/O and Analog pins, but received only an ERROR message. According to their documentation, we should just be able to do the following:

Enabling the A/D’s:
The XBee has 6 usable A/D pins on it that allow the user to select one or all of those A/D’s (assuming sufficiently slow sample rates are chosen i.e. 1KHz/6 = 167Hz). The A/D feature can be enabled with the ATDx=2 command where x= 0-5(the A/D pin you wish to use). In order for the module to be able to read analog signals Vref must be tied to an appropriate voltage (0 < Vref <= Vcc).

We emailed their tech support, and hopefully they’ll have some advice on troubleshooting.

I’m reading up on Repeater functionality (“Using Repeaters in a Wireless Network”).

Just got the mini Arduino board & USB connector yesterday. Tested with the good ol’ test blinky LED. Click on pic for basic setup notes.

I referred to these pages for setup:

http://www.arduino.cc/en/Main/ArduinoMiniUSB
http://www.arduino.cc/playground/Learning/ArduinoMini
http://janeoh.wordpress.com/2006/11/09/mini-arduino/ (thanks, Jane!)

I recently attended this workshop led by former ITPer, Jeff Feddersen at Eyebeam. He discussed the basics of energy, how humans have manipulated/stored it through history, electricity, solar energy and its current status. Here’s what I learned:

So how far are we from seeing wider usage of solar power in cities, products, etc? At this point in time, solar power is about 8-35% effective, with the higher grade stuff being used by NASA. Solar panels react to certain frequencies of light, which is another reason they’re not so efficient. The cost is also still pretty high, as it’s still labor intensive to produce and requires growing crystals within a very controlled environment; the size needed for the supporting infrastructure is also another factor keeping the cost up.
There are a few different types of panels you can purchase:

• monocrystalline - darker in appearance, more efficient and costly. Example shown in workshop was the SINONAR SC-9225
• multicrystalline or polycrystalline - least efficient, cheapest to make. However, these panels have a more interesting, reflective pattern and Paul commented on its possible appeal for usage in fashion & wearable technology
• thin film - can almost be printed. Instead of grown crystals, these are sprayed on. Currently, these are not very efficient at all, but also have application toward wearable tech

Batteries end up doubling the cost of trying to implement solar energy use. In addition, our limitation in manipulating materials make batteries a bad storage of energy (esp. in comparison to how our bodies store energy).

The last hour or so of the workshop was spent building a “solar insect” (kits came from solarbotics.com & the instructions are featured in Vol. 6 of MAKE magazine). This was a lot of fun, and extremely satisfying to see our bots jitter slightly under the desklamps.

All in all, this was a great workshop and a good intro to the basics of energy and solar power. Since my undergrad studies in product design, I’ve been interested in sustainability, and renewable/recyclable materials. The building of the BEAMbots was like an appetizer and I think most of us were eager to try out more and experiment with other projects. It would be great to have a part 2 and up, or a more fully developed class in this topic.

Additional related links & resources:

• Jeff’s recommended reading: The Bottomless Well
• Schematic for basic solar engine

Still working on getting all my documentation organized - here’s what I presented

My physical computing journal from MLuck’s site