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Part list

Partname Amount Position on PCB Bauteilsortiment known bugs
LED 5mm BLUE 1 D1 -
LED 5mm GREEN 1 D2 G4
LED 5mm YELLOW 1 D3 -
LED 5mm RED 1 D4 H4
Pushbutton 4 SW1, SW2, SW3, SW4 E9
Piezo beeper 1 U3 S7
2x16 Pol, RM 2.00 1 U1 C5 needs 2x6 pin socket
RFM12B Radio module 1 U1 K8
28 PIN DIP Socket 1 IC4 D9
ATMEGA328P 1 IC4 -
10 uF Capacitor (elko) 1 C4 E0
22 pF Capacitor (ceramic) 2 C1, C2 A2
100 nF Capacitor (ceramic) 1 C3 C2 imprint unter loch
16 Mhz Crystal 1 CRYSTAL1 L0
9V battery clip 1 JP3 T3 imprint should say +/- not J3 ;)
FTDI connector 1 JP4 B6
Resistor 100 ohm 1 R10 N1 nicht bestücken! (R10)
Resistor 10K ohm 1 R9 P3
Resistor 1K ohm 7 R5, R6, R7, R11, R12, R13 O2
Resistor 680 ohm 4 R1,R2,R3,R4  ? am plan noch als 1k eingezeichnet
Resistor 4K7 ohm 1 R8 -
RGB LED 5mm 1 D5 -
Switch MIYAMA MS 245 1 SW5 S9 connect over cable!


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).


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.


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.