I2C object creation in Simulink

Hi,

im trying to create an i2c object in simulink for reading an sensor. In Matlab every thing works fine and i can read the data out of the sensor :

mpu_6050 = i2c('aardvark',0,hex2dec('68'));
fopen(mpu_6050);
fwrite(mpu_6050,65);
y = fread(mpu_6050,1);
fclose(mpu_6050);

When i try to add an Matlab-Function-Block to Simulink:

function y = mpu6050_read()
mpu_6050 = i2c('aardvark',0,hex2dec('68'));
fopen(mpu_6050);
fwrite(mpu_6050,65);
y = fread(mpu_6050,1,'*char');
fclose(mpu_6050);
end

i will get this error:

The 'i2c' class does not support code generation.

Is it really not possible to use the i2c class in simulink or do i have to use it in another way?

Regards V.Sadiku

[Kaustubha Govind]

Would you like to simply use your Simulink model for simulation within the MATLAB environment, or do you also intend to generate standalone C/C++ code from it?

[Valmir Sadiku]

I want only use the Simulink model only for simulation, that's why i don't understand this error message.

Answer 1

[Kaustubha Govind]

The MATLAB Function block always generates C-code from the MATLAB code for faster execution. If you intend to run the block only for simulation, you can continue to use functions unsupported for code-generation by declaring them as extrinsic functions. I don't think fopen, fwrite, fread and fclose are supposed for code-generation either, so please declare all of them as extrinsic. You will also need to pre-allocate the output of fread, 'y', as described in this previously answered question.

[Valmir Sadiku]

Thank you a lot, now it works fine :-)

[Valmir Sadiku]

Now i have an additional question: I would use it with the Windows Real Time Target, is it possible? It would be very nice if i can use it or it exits any workaround for that!

Regards V.Sadiku

[Kaustubha Govind]

I would recommend creating a new question for this to make sure other experts see this. I would guess that this is not possible, because coder.extrinsic is meant for execution within the MATLAB environment only. Targets like Real-Time Windows Target create a standalone binary that runs outside the MATLAB environment (in this case, a Real-Time Windows kernel, I believe). The only workaround is to create your own C implementation of that functionality and call it using coder.ceval.