Metaboard/2010 activities

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As of September 2010, reox and chrysn are about to build some microcontroller stuff, partially based on the metaboard, and centered around home automation.

People who want to participate are invited to join, even if there is just a small overlap between the things we build!

Some current files are in gitorious (clone using "git clone git://gitorious.org/metaboard/metaboard.git metaboard").

Goals

  • Physical goals:
    • Build remote sensors that monitor room parameters; those should be as cheap as possible (<10€)
    • Build a base station for those sensors that can be used both for receiving and programming the sensors
    • Build a version of said base station that can also control that can emit DMX signals
  • Learning goals:
    • Planning a physical computing device from standard components
    • Physically creating the devices
  • Community interaction goals:
    • Document the learning experience
    • Enhance tools used
    • Create a version of metaboard that can be edited using free tools

Random extension ideas

  • IR transceiver for integration with TV or universal remotes
  • Measuring water level in indoor fountains
  • wireless or opto-coupled USB-to-USB keyboard/mouse or serial device
    • could double as a replacement for serial terminal / null modem connections (violates USB specs, but should work with Linux)

Implementation

  • Microcontrollers: Atmel AVR (ATmega and ATtiny; chosen for availability of existing infrastructure (gcc, arduino libraries) and widespread use in similar applications)
  • PCB implementation: single sided PCB with no SMD components
  • Board base: metaboard (at least for the base station)
  • RF communication: ISM band using HopeRF RFM12B
  • Computer communication: V-USB (works with metaboard, is cheap and much cooler than relying on serial port emulation)
  • Layouting software: gEDA seems to be the best free schematic and PCB editor
  • Board voltage: 3.3V (originally 5V, but 3.3V gives cleaner USB communication and should save power in the sensor units)
  • Flashing sensors using serial interface using the Metaboard/2010 activities/6-pin auto-detecting programming

Random implementation detail notes

  • Some AVR boards have onboard temperature sensors that don't block an external pin. Given sufficiently low power output and sensor precision, those could be used for monitoring room temperature.
  • The RFM12B modules feature low voltage detection. This could save some analog circuicy and pin on boards fed off battery w/o a voltage regulator.

Parts

for the base board (metaboard + DMX + RF12)

this is partially outdated due to the change to 3.3V board voltage

  • a 5V voltage regulator (7805)*
  • capacitors: 100nF, 22pF (2x)
  • clock crystal: 16MHz (for other frequencies, check the V-USB hardware considerations)
  • diodes: 1N4004*, 3V6 (2x)
  • jumper pads of length 3 (2x) and 2
  • "negative jumper pads" (or whatever they are called) of length 2, 4, 6 and 8 (2x)
  • polarized capacitors: 10µF (2x) (*: 1x)
  • power jack*
  • resistors: 68Ω (2x), 100Ω*, 1.5kΩ, 1MΩ
  • RS485 driver: SN78176a*
  • push button
  • ATMega168 (or 328)
  • RFM12 DIP*
  • USB-B connector
  • DIP sockets: 8*, 28
  • socket for RFM12 DIP (2mm 2x4)*

The components marked with * are optional in the first stage of building the board, which will be about getting to know V-USB.

Current status

Resources

Existing similar solutions

(We could probably directly go for some of them, but doing it all ourselves gives more flexibility and a learning experience.)

Physical resources

We hope to be granted access to Metalab / WhateverLab resources for physically creating the boards (PCB etching (or milling?), solder station, parts repository / order collections), and will approach metalabbers as soon as we know what we want at all.

Other Links

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