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Matlab serial command to read binary data

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Jason Chen
Jason Chen on 17 Oct 2014
Commented: Jason Chen on 17 Oct 2014
I want to communicate with an Arduino board using Matlab through a serial port. The Arduino board will transmit 8 bytes of BINARY data every 20 ms once it receives a 1. The transmission will stop if the Arduino receives a 0.
The following commands in an m-file work as expected when I step through them in the debug mode. However, the transmission stopped immediately when I ran the m-file. The s.BytesAvailable is zero. It looks like the pause command has not properly executed. Why was wrong? How can I fix it? Thanks.
s = serial('COM15','BaudRate',115200);
fopen(s);
fwrite(s,1); %ask Arduino to send data
tic;pause(3);toc %wait for several data to arrive
fwrite(s,0); %ask Arduino to stop sending data
fprintf(1,'%i\n\n',s.BytesAvailable)
fclose(s)
  2 Comments
Jason Chen
Jason Chen on 17 Oct 2014
The code worked when I stepped through them in the debug mode. The com port and baud rate are not the problem. I think it has to do with the execution timing.

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Answers (1)

Sean de Wolski
Sean de Wolski on 17 Oct 2014
You might be interested in doing this with the support package directly rather than using the serial port yourself
  1 Comment
Jason Chen
Jason Chen on 17 Oct 2014
Mathworks states that the Matlab support package is not real time and the loop time can't be less than 40 ms (25 Hz). I'm using an Arduino for a real time application and like to transfer data to the computer to display later. I hope the serial data buffer can catch the data at faster rate.
I tried the Simulink Arduino support package. It doesn't work well in external mode either, especially for Due.

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