Shared memory (read and write) in Simulink model on Raspberry Pi

Hello everyone,

I would like to access shared memory in a Simulink model that runs on a Raspberry Pi 3 B+. I want to exchange data with another process running on RPi. I couldn't find anything applicable. Can anyone help me? Thank you!

Answer 1

[Ayush]

Dear Raphael,

I understand that you are working with Simulink and Raspberry Pi 3B+ and you want to exchange data with another process running on the Raspberry Pi.

To access shared memory in a Simulink model on a Raspberry Pi, you can write a C code that implements the steps mentioned below. Then, you can use the Simulink Coder Support Package for Raspberry Pi to generate and deploy a Simulink model that calls this code. You can integrate your C code with your Simulink model using either the MATLAB Function block or the S-Function block.

Here are the steps to create the C code:

• Create a shared memory segment using the "shmget" function in C. You need to specify a unique key, the size of the segment, and the permission flags.
• Attach the shared memory segment to your process using the "shmat" function. This will return a pointer to the shared memory location.
• Use the pointer to read or write data to the shared memory segment. You can use any data type or structure that fits within the segment size.
• Detach the shared memory segment from your process using the "shmdt" function when you are done.
• Delete the shared memory segment using the "shmctl" function with the "IPC_RMID" command when it is no longer needed.

For more detailed guidance on writing the C code and deploying your application on Raspberry Pi with Simulink, please refer to the following links:

1. Shared memory in C: https://raspberry-projects.com/pi/programming-in-c/memory/shared-memory
2. Simulink deployment on Raspberry Pi: https://in.mathworks.com/help/supportpkg/raspberrypi/ug/create-and-run-an-application-on-raspberry_pi-hardware.html
3. MATLAB Function Block: https://in.mathworks.com/help/simulink/what-is-a-matlab-function-block.html
4. MATLAB S-Function block: https://in.mathworks.com/help/simulink/matlab-s-functions-1.html

Hope this helps!

Best regards,

Ayush Goyal