TinyFinger is a small device powered by an ATtiny45 to produce pseudorandom numbers for selecting student groups during the computer science hardware courses at Leipzig University.
The board is designed in KiCad and uses a single sided pcb layout using mostly SMD components. The routing was done manually.
The firmware for the ATtiny is written as an Arduino sketch using the ATTinyCore board definitions. It uses a linear congruential generator for generating pseudorandom numbers and transforms them to the needed range using the gcc uniform_int_dist c++std implementation.
Flashing the firmware can be done using a usual Arduino (UNO in our case) programmed as an ISP with the ArduinoISP example sketch included in the IDE.
Then the Programmer (Arduino) should be connected to the Target like this:
|Programmer’s pins||Target’s pins|
The pins on our TinyFinger board are from left to right: GND, MISO, VCC, SCK, MOSI, RESET.
The case is modelled in Blender and intended for 3d printing, e.g. using Cura after exporting the model as an stl file.