Writing to file in compiled c code from simulink model, on Raspberry Pi

Hello,

I am trying to write to file in a simulink model that I will later deploy and run as standalone on the Pi.

I have tried a few different versions with no success. When run in external mode in simulink it works with all the solutions, but when i run the built executable from the modelname/MW/ folder on the pie, no file is written.

function savePoints(points, time)
%#codegen

coder.cinclude('<stdio.h>');
format = ['%d ', 0];
formatTime = ['%f ', 0];
fname  = coder.nullcopy(uint8(zeros(1, 32)));
coder.ceval('sprintf', coder.wref(fname), ['testPoints.dat', 0]);
fd = coder.opaque('FILE *');
fd = coder.ceval('fopen', fname, ['a', 0]);
coder.ceval('fprintf', fd, formatTime, time);
for i = 1:272
        coder.ceval('fprintf', fd, format, int32(points(i)));
end
coder.ceval('fprintf', fd, [char(10) 0]);
coder.ceval('fclose', fd);

Above you can see one attempt, which is a rewamp of the motion sensor example code provided by Mathworks.

I have studied the c code, and it seems "right" as far as I can see, it should write a new line to the file each cycle in the model, and close the file each time. As such, even if it is terminated early/not at all, at some point there should be a file created?

Anyone have any experience with these type of issues? As I said, it works fine when run in external mode.

Have also tried with the "tofile" block, but I have a feeling I have seen somewhere that it does not compile. It behavs similar to my code anyway. Any help would be appriciated!

[Ryan Livingston]

MATLAB Coder supports generating code for the MATLAB fopen, fprintf, and fclose starting in R2013a. You could consider using those and skipping the coder.ceval code if using a sufficiently new version.

Answer 1

[Jonas Landberg]

Got help from the Mathworks support. If anyone have similar problems in the future:

It does work, but if you want to run the standalone version on the pi, build the code using normal and not external. So use realtime target, select the pi as a target, running mode normal, then ctrl-b in the toplevel of the model. Good luck!

[Adil Faiz]

Hey, i need some help ,I m building a robot using vision for line following,is it possible that i can code in matlab for pi and made it as autonomous by image processing ,i mean do i have to give live commands to pi through wired or wireless connection to pi for processing,may be i am not clear as i am naive using raspberry pi for image processing .