Implement an asynchronous online SSVEP-based brain computer interface
The research of brain computer interface (BCI) has important theoretical significance and wide application prospect. The BCI system based on Steady-state visual evoked potentials (SSVEP) has the advantages of noninvasive signal recording, little training required for users, high information transfer rate(ITR), and ease of use. However, most of the applications based on SSVEP-based BCI are synchronous. One of the important factors is the limitation of visual stimulators. In this paper, a new low-cost stimulator flashing with accurate frequency output was designed. By this way, the computer monitor can be used as a feedback interface for the online system. The stimulator consists of LED stimulation panel derived by FPGA chip. Experiments with ten subjects were performed, and the results demonstrate that the stimulus frequency generated using the proposed scheme was accurate, and the developed SSVEP-based brain computer interface is feasible for use.