HSC2011/Hardware

Specification

Nodes are supposed to be equipped with:

• RF transceiver
• 4 buttons, labelled with digits, letters, colours (probably red / blue / green / yelow) and symbols (playstation style?)
• a LED for each button in matching colour
• an RGB LED
• a buzzer
• a 1-wire interface for authentication buttons (iButton)

For ease of development, they also get a serial interface ("FTDI cable" -- power supply + RX/TX + reset, also for flashing using a boot loader).

Implementation

Both for development and for the final version (as far as we know now), an ATMega328 is used; for development, encased in an Arduino, which also binds the RX/TX pins to a USB serial interface.

As an RF module, RFM12B is used.

The wiring is defined in an eagle file in the project repository.

RFM12B

A little very unprofessional test showed that with the current configuration (through-hole mounted RFM12B with the wire antennae bent to the opposite direction of the pins) with a sender at the whateverlab solder stations a receiver starts losing 6-long packets some steps outside the metalab door front and in the library. Even without further optimization, that should be sufficient for typical class rooms.

Experiments showed that sending a login packet takes about 10ms.