The Design And Implementation Of An EEG Signal Acquisition System Based On STM32

Electroencephalogram(EEG)is a method of recording brain activity by using electrophysiological indicators.When the brain is active,the sum of post-synaptic potentials generated by a large number of neurons synchronously.As a typical bioelectrical signal,EEG contains abundant physiological information and pathological information.In today's medical research and other fields of science,more and more attention is being paid.Because EEG signals are very weak and extremely unstable,it is difficult to extract meaningful signals from complex EEG signals by visual analysis alone.Aiming at the above defects,this paper designs a set of high accuracy,small volume,fast signal transmission rate,stable transmission,portable and low power consumption real-time online acquisition and display system.Due to brain electrical signal is very weak,so I must choose higher precision of sampling for human brain electrical signal conversion chip,the system adopts 24 high precision ADS1298 as the collection and conversion chip,The chip can accurately identify the smallest changes in EEG signals.Analog front end ADS 1298 collects data in internal A/D conversion processing through the SPI communication mode to STM32 master controller.The main controller transmits the data wirelessly to the Lab VIEW upper computer via bluetooth,The upper computer is used to de-noising the EEG data transmitted from the lower computer and display the waveform before and after filtering in real time by the filtering algorithm such as the frequency trap and the butterworth filter.Finally,Empirical Mode Decomposition(EMD)algorithm is adopted to analyze and process Brain wave signals in all frequency bands,and enffective characteristic waves are extracted,laying a good experimental foundation for the Brain Computer Interface(BCI)experiment in the future.Later,a set of visual stimulus sequences are designed and P300 evoked potentials caused by steady-state vision,and analysis,processing of P300 potential.This signal is of great significance for psychology and neuroclinical medicine.After a large number of human experimental tests,this EEG acquisition system can accurately non-invasive collect human EEG signals and realize real-time online display of brain waves.