Can't open /dev/ttyRPMSG0 :(

[AShva.1]

I'm trying execution code:

#define DEVICE "/dev/ttyRPMSG0"
 
int main(void)
{
    int fd;
    struct termios tty;
    char buf[100];
    int len;
 
    printf("Opening device...\n");
    fd = open( DEVICE, O_RDWR | O_NOCTTY | O_NDELAY );    // read/write, no console, no delay
    if ( fd < 0 )
    {
        printf("Error, cannot open device\n");
        return 1;
    }
}

But, always get: Error, cannot open device. :(

I think, that in my Linux system there is no driver for this device: /dev/ttyRPMSG0.

What am I doing wrong?

How to create and manage a device /dev/ttyRPMSG0 from a program correctly?

Board: STM32MP157C-DK2

Many thanks.

[nick67 · Accepted solution]

Hi AShva.1,

let me share with you the two projects attached to this message (they are compressed in a single zip file).

One runs on Cortex-A7 and the other on Cortex-M4.

Virtual UART is created in Cortex-M4 project, in the main.c file.

Then, in Cortex-M7 project you can find the connection from A7 processor to the Virtual UART created before from M4 processor:

The full application aims to build a user interface on the LCD touch screen via GtkBuilder on Cortex-A7.

Then you'll obtain three graphic buttons that, once pressed, send a message through IPCC to the Cortex-M4.

This one receives the message, decode it and toggles the related LED:

Please note that in this project first the Cortex-M4 has to create the virtual UART and then the Cortex-A7 can connect to this UART.

Hope it could be useful.

Regards

Nicola

[AShva.1]

Nicola!

thank you very much!!!

I will do and write...

Best regards

Alexander.

[AShva.1]

Nicola!

I'm trying import project cortex_M4-hrdbtn_IPCC to System Workbech for STM32 IDE.

Very much errors :(

Please, write me, how to do it right.

Best regards

Alexander.

operating system: Ubuntu 16.04

[nick67]

Hi Alexander,

my fault. I didn't remember to mention that the projects are for STM32CubeIDE 1.2.0

You can download it from this page:

https://www.st.com/en/development-tools/stm32cubeide.html

Best regards

Nicola

operating system : XUbuntu 18.04

[AShva.1]

Hi Nicola!

Thank you!

I will try. :)

Best regards

Alexander.

[AShva.1]

Hi, Nicola!

Many thanks.

Your project works great. :)

I have a few new questions:

1. How to organize a transmission channel from M4 to A7?
2. Can i use OPENAMP without HAL?

I would be very happy if you provide examples. :)

Best regards

Alexander.

[nick67]

Hi, Alexander.

I'm glad to hear that the project works for you.

Unfortunately I didn't develop any more this kind of application so I can't provide other examples about IPCC :worried_face:

My first attempts started with the project OpenAMP_TTY_echo (attached here for your convenience) from STM32Cube_FW_MP1_V1.1.0 : https://wiki.st.com/stm32mpu/wiki/Install_STM32Cube_MP1_package

Lately I'm trying to have a better understanding of ADC management, peripheral sharing between CA7 and CM4 and Device Tree usage in OpenSTLinux.

Best regards

Nicola

[AShva.1]

Hi, Nicola!

I understood you.

Many thanks for the help.

Best regards

Alexander.