Metaboard/2010 activities

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!

chrysn: base station, DMX
reox: sensor modules
derdritte
...

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
Power supply: "18650" (z.B. von dealextreme)

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

Metaboard/2010 activities/Hacksession 2010-09-17: bootstrapped a an ATmega168 via an existing arduino on a breadboard
Metaboard/2010 activities/Hacksession 2010-09-20: arduino style programming on the breadboard
Metaboard/2010 activities/Hacksession 2010-10-14: LEDs are important
2010-10-29: built first (and working!) version of the usbBB, a USB connector for breadboards which is our first attempt in PCB milling
2010-11-10: Prototype v3 (without USB Port and LF33CV because just ordered them)
2011-03-15: Hacking arround with HP54645D_Mixed-Signal_Oscilloscope and see whats going on at sck, sdi, sdo and irq
2011-03-20: WOOOHOOO got something over the air, used mostly code from here... also: datasheet gone wrong... port with ANT marking is in real GND, ANT Port is next to it!
2011-03-25: If it works at 5V and doesn't at 3.3V, just try adding a startup delay. Hacking on based on jeelabs' RF12 library now.

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.)

JeeLabs: Arduino compatible boards running on 3.3V with RFM12B modules and a plug system for sensor components
cm's wireless temperature and humidity sensor with USB interface: one of the V-USB example projects, pretty close to what we want to build
Arduino DMX shield: pretty straight forward DMX master
iPhone and DMX: Arduino with DMX and ethernet shield
RFM12 transceiver module: a board with ATmega8, with the RFM12 completely connected (see schematics)
Benutzer:Mihi/Programming-attiny45-mit-arduino: programming arduinos with arduinos
The vKeyBoard mentioned on the Teensy project page seems to do exactly the USB-to-USB trick described above, but using two Teensy boards, which use an ATMega32U4 each. These chips might even provide a way to get the desired functionality in one chip by using vUSB to get a second USB port and optocouplers USB-side, but they are rather difficult to work with unless preassembled in a teensy.

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.

Metaboard/2010 activities

Inhaltsverzeichnis

Goals

Random extension ideas

Implementation

Random implementation detail notes

Parts

for the base board (metaboard + DMX + RF12)

Current status

Resources

Existing similar solutions

Physical resources

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