Tag Archives: watchdog

Video: Electronic dice go random with AVR

A Maker named Walter recently created an entropy library for Atmel AVR microcontrollers (MCUs) to ensure a reliable source of truly arbitrary numbers.

As HackADay’s Brian Benchoff reports, the electronic dice generate random numbers by taking advantage of the watchdog timer’s natural jitter.

“[This isn’t] fast by any means but most sources of entropy aren’t that fast anyway,” Benchoff explains. “By sampling a whole lot of AVR chips and doing a few statistical tests, it turns out this library is actually a pretty good source of randomness, at least as good as a pair of dice.”

According to Benchoff, the circuit itself employs a pair of 8×8 LED matrices from Adafruit, an Atmel-based Arduino board and a pair of buttons.

Supported modes (11 total)?

  • 2d6
  • 2d4
  • 2d8
  • 2d10
  • 1d12
  • 1d20
  • Deck of cards
  • Single hex number
  • Single 8-bit binary number
  • 8 character alphanumeric password

Interested in learning more? You can watch the video above or check out the project’s official page here.

LIN networking for the automotive masses

LIN (Local Interconnect Network) is a serial network protocol used for communication between various vehicle components. The LIN Consortium was founded by five automakers (BMW, Volkswagen Audi Group, Volvo Cars, DaimlerChrysler) in the late 1990s, with the first fully implemented version of the new LIN specification (1.3) published in November 2002. Version 2.0 was introduced in September 2003, offering expanded capabilities and support for additional diagnostics features.

Specifically, low-cost local interconnect networking (LIN) systems are used throughout the automobile in comfort, powertrain, sensor and actuator applications. Vehicular LIN applications include roofs (sensors), steering wheels (cruise control, wiper, turning light, climate control, radio), seats (position motors, occupant sensors, control panels), engines (sensors), climate control (small motors, control panel) and doors (mirror, central ECU, mirror switch, window lift, seat control switch, door lock).

Atmel offers unique BCD-on-SOI technology for LIN, which combines high-voltage capability with the benefits of rugged SOI technology: high temperature resistance (T-junctions up to 200°C), optimized radiation hardness, very low leakage currents, low parasitics, high switching frequency and latch-up immunity.

“Our LIN devices operate in standard temperature environments to support roof, door, and car body sensors among others. They also perform flawlessly in very hot engine environments, up to 150°C/302°F ambient air temperatures,” an Atmel engineer told Bits & Pieces.

“The modular Atmel LIN family ranges from simple transceiver ICs to complex system basis chips with LIN transceiver and voltage regulator. At higher integration levels, our System-in-Package (SIP) solutions feature an Atmel AVR microcontroller, LIN transceiver, voltage regulator and watchdog in a single package.”

Interested in learning more about Atmel’s LIN solutions? Additional information is available here.