This was the final project for an introductory electronics course, it completed with Corten Singer. Extra credit was given proportional to the extra features we added and inversely proportional to the board area occupied the EEG circuit, which should explain everything.
The eeg circuit is on the left. The rest of the board contains two microcontrollers(bottom right), an SD card holder(U14), an OLED screen(U13), 4 buttons(top right) and 4 LEDs. The first microcontroller handles the OLED, buttons, and LEDs while the other accepts datalogging commands from the first and logs EEG data to the SD card. It can also return values for the OLED display. Having two microcontrollers allows for uninterrupted data collection on consistent intervals while maintaining input and display responsiveness. The microcontrollers run the Arduino bootloader.
Unfortunately, there was a mixup and a previous version of the board
layout got sent to the PCB manufacturer that did not contain
the datalogging part. Here is the final assembled eeg portion:
The rest had to be bread-boarded instead: