Value of last stimulus presented

[mumair]

Hi,

i am trying to implement a p300 speller with matlab signal processing. I want to know where the value of the last flashed row/col is stored. StimulusCode stores the value only for the period that the stimulus is presented. is there a state which stores the last stimulus code until the next stimulus is presented ? and is it accessible in matlab ?

My sample block size is 500ms. I am presenting stimulus and recording data for 500ms before presenting the next stimulus so that there is no overlap (this is just for initial stages to form a base before implementing in C and improving speed and accuracy). So i want to know the code of last flash for my signal processing in matlab. Any help will be appreciated.

Thanks.

[mellinger]

Hi,

there is no such state variable, as it would be completely redundant. Just create a LastStimulusCode global variable on the Matlab side to hold the desired information. Then, in bci_Process(), assign the current value of StimulusCode whenever it is nonzero. This way, your LastStimulusCode variable will give you the information you need.

-Juergen