About Matlab and the lua p300 speller accumulator

[Ivan Santos]

Hello to the community.
I have a problem, I want to get the outputs of the lua accumulator p300 (which are the stimulation of the rows and columns of the P300 array) and use them as inputs in a matlab scripting box for the process function. That is to say that the process function obtains as input the outputs of the lua accumulator P300. However I do not know how to do it. Thank you for your future answers.
The code of the stimulation outputs of the lua speller accumulator is:

box:send_stimulation(1, maxRowIdx + row_base, now, 0)

box:send_stimulation(2, maxColIdx + col_base, now, 0)

And my matlab code for the procces function is:

function box_out = robotarm_process(box_in)

row = box_in.inputs{1}.matrix_data;
col = box_in.inputs{2}.matrix_data;

But I get the following error in openvibe

Reference to non-existent field 'matrix_data'.

Help please,

[jtlindgren]

Hello Ivan,

you can take a look at tuto1_signal_filter_Process.m file bundled with openvibe. There, in the first for() loop of the function, you will see an example how to extract stimulations from the input stream.

Hope this helps,
Jussi

[Ivan Santos]

Thanks for the last answer.
Watching the tutorial tuto1_signal_filter_Process and associating it with my matlab processing function
as shown:
function box_out = robotarm_process(box_in)
for i = 1: OV_getNbPendingInputChunk(box_in,2)
[box_in, start_time, end_time, row] = OV_popInputBuffer(box_in,1);
[box_in, start_time, end_time, col] = OV_popInputBuffer(box_in,2);

if(row~=0 & col~=0)
disp(row);
disp(col);
end
end
end
I note that the values ​​obtained are always zero for row and col as shown:
- MATLAB BUFFER - INFO ----
0
0
Therefore I can not go to the next part of the code, What can I do about it?
Maybe the values ​​are of the form 0x00008101 and when printing them on the screen gives zero, if that is the case as I can get the decimal value, since the hex2dec function generates errors
Another question there will be some way to debug the program?

Thanks for your future answers