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The internet community quite enjoying the destabilizing effects of global connectivity on the status quo, fights any attempt at restriction tooth and nail. Organizing themselves both on- and offline they managed to stop anti-piracy laws like the Stop Online Piracy Act (SOPA) or the Protect IP Act (PIPA) from passing. But it wouldn’t be the internet community if people weren’t working on technological solutions as well. Hackers, engineers and freedom-loving folk are working to create a decentralized, independent network where you can’t stop the signal. [via]
Build a Solar Powered Wikipedia Server - [Link]
A Wireless XBee Pan/Tilt Servo System For Cameras. It uses a pair of XBee modules to build a simple wireless interface which will be used with PIC 18LF4520′s to control a servo based pan and tilt system which can move my camera 45 degrees in any direction, left-right-forward-backwards.
Wireless XBee Pan/Tilt System - [Link]
Microchip compares mechanical and digital potentiometers to digital. This app note explains the theory behind both versions, and their advantages and disadvantages. [via]
Mechanical potentiometers have advantages in terms of having a wide variety of values available and tighter specifications such as nominal resistance, tolerance, temperature coefficient, power rating and temperature range specifications. But in many applications the overriding
factors are related to environmental and reliability issues. These characteristics are not necessarily specified by the mechanical potentiometer vendor.Digital potentiometers go hand in hand with the drive towards digital system control. This type of potentiometer is considerably more robust that its predecessor, the mechanical potentiometer, in terms of environmental exposure issues and longevity with repeated use of the wiper. But beyond the reliability issues, the digital potentiometer offers hands-off programmability. This programmability also allows the user to repeatedly and reliably return to the same wiper position.
Comparing digital and mechanical potentiometers - [Link]
Luca is designing a nixie clock that will be run from an Arduino. In the latest development he shows to to implement a real time clock source and a port expander to drive the nixies. [via]
In this third blog post, I’m going to show you the logical view of my Nixie clock and two of its main elements: the real time clock, to keep track of the current time, and the expander, to add more I/O lines.
RTC and port expander for an Arduino nixie clock - [Link]
TDK Components describes how to handle chip capacitors to avoid cracking. Multilayer ceramic capacitors are very brittle components, and can be damaged if proper care isn’t taken. [via]
Multilayer ceramic capacitors should be handled very carefully during mounting, soldering, and handling. Any damage incurred during these processes, no matter how small, can contribute to premature component failure. Handling a PCB with soldered components should be done with care to avoid any bending of the board. If steps outlined in this paper are followed, MLCC cracking can be avoided successfully.
Frequently asked questions about chip capacitor cracking - [Link]
Atmel describes how to select and test 32.768 kHz quartz crystals [PDF!] for real-time clocks. The basic tips on layout apply to any microcontroller project, not just those with AVRs. [via]
This application note summarizes the crystal basics, PCB layout considerations, and how to test a crystal in your application. A crystal selection guide shows recommended crystals tested by experts and found suitable for various oscillator modules in different Atmel AVR families. Test firmware and test reports from various crystal vendors are included.
Selecting and testing 32kHz crystal oscillators - [Link]
dangerousprototypes.com writes:
Flylogic is known for their skills in reverse engineering chips. They were familiar with Atmel smartcards AT90SC3232 and AT90SC3232C and assumed that the AT90SC3232CS was similar but with an extra IO pad. They discovered the AT90SC3232CS is a completely new design based on the larger AT90SC6464C device,
Get all the fascinating details on the exploration of this smartcard and images at Flylogic’s Analytical Blog.
Atmel AT90SC3232CS smartcard destruction - [Link]
Jbeale connected the MAX11209 18 bit ADC to his Seeeduino board and wrote up some test firmware. [via]
The MAX11209 can do 18 bits at sample rates up to 120 Hz (true) or 480 Hz (4x oversampled). It has both external analog and internal digital scaling. There is +Vref and -Vref, as well as +Vin and -Vin, so you can set your own full-range scale and offset via analog voltages (many ADCs have only +Vref, so you can’t set your own analog offset above ground). Maximum Vin = 3.6 V. The data sheet claim that CS/ can be tied low is apparently false (must be brought high after each SPI transaction).
The 11209 is part of a family, some other variants do 24 bits (although there I think some bits will be just noise). With the 11209 I can so far confirm that the input noise is less than 2 uV at a 15 Hz rate. Datasheet claims 0.57 uV RMS at 10 Hz.
Using the MAX11209 18bit ADC - [Link]
Abdullah explored the idea of driving two character LCDs in parallel. When he couldn’t find any information about this online, he decided to try it out himself. [via]
Then I thought about it and I gave it a go. The result is positive! However, there is a gotcha; if you are using LCDs from different manufacturers or different types, the contrast setting might differ, as it did in my example. In order to overcome this, I would suggest putting two potentiometers in your board to adjust the contrasts individually. And don’t forget, you are using one more LCD, meaning more back light current. If you are using a 7805 without a heat-sink, you should re-calculate your thermal values.
Driving two character LCDs in parallel - [Link]
dangerousprototypes.com writes:
The 2012 Atmel Robotics Contest (ARC) is currently underway. The contest is open to university students 18 years or older in North America, South America and Europe, and the goal is to develop a battery-powered 3D version of the Atmel robot ‘Mel’ (pictured above) using Arduino’s 4WD platform (for example, see Seeedstudio’s version) and Atmel components. Contestants can either work on their own or team up with other university students.
Deadline for submissions is May 18th, 2012. ARC contest rules are available in PDF from the contest webpage.
Atmel University Program Kicks Off 2012 Robotics Contest - [Link]
