• Table of contents
• PRU example: build and run RPMsg program on PRU_1
  • • Objective
    • Steps
      • Create and build the PRU program
      • Copy PRU program to target and start
      • Manually send messages to the PRU
      • Create an ARM program to send and receive messages from the PRU
    • Summary

PRU example: build and run RPMsg program on PRU_1¶

Objective¶

The objective of this example is to build and run an RPMsg program which will run a program on the PRU which will echo a message sent from the ARM so the message is received by the ARM.

This example will not demonstrate new debugging techniques but it does create a multi-processor example that will be debugged in the next example.

This example performs most of the target interaction through the use of a Terminal view in Code Composer. Since Code Composer is not able to make a SSH Terminal connection directly to the target, the target communications is performed by creating a Local Window on the host and then using ssh/scp commands within that window. The target interactions would probably be easier if a direct console connection were used instead but it seems useful to know how to do everything within Code Composer.

Steps¶

Create and build the PRU program¶

• Start a new workspace
• Create a new CCS project
  • Processor is AM62x
  • Select the PRU tab
  • Name the project: rpmsg_echo
  • Empty Project
  • Finish
• Add source file
  • Project->Add Files...
  • Browse to location below and Add all files except Makefile. Copy to workspace

~/ti-processor-sdk-linux-am62xx-evm-08.06.00.42/example-applications/pru-icss-6.1.0/labs/Hands_on_Labs/lab_5/solution/am62x/PRU_RPMsg_Echo_Interrupt1

• Modify main.c
  • Change CHAN_NAME to rpmsg-pru. Before
    

    #define CHAN_NAME            "rpmsg-client-sample" 
    //#define CHAN_NAME            "rpmsg-pru" 
    

    
    After
    

    //#define CHAN_NAME            "rpmsg-client-sample" 
    #define CHAN_NAME            "rpmsg-pru" 
    

• Modify Project Properties (Project->Properties)
  • Compiler Include Paths (Project->Properties->PRU Compiler->Include Options)
    • Delete ${CCS_BASE_ROOT}/pru/include
    • Add ~/ti-processor-sdk-linux-am62xx-evm-08.06.00.42/example-applications/pru-icss-6.1.0/include/am62x
    • Add ~/ti-processor-sdk-linux-am62xx-evm-08.06.00.42/example-applications/pru-icss-6.1.0/include
  • Linker Heap and Stack sizes (Project->Properties->PRU Linker->Basic Options)
    • Heap size of 1024
    • Stack size of 1024
  • Linker Libraries (Project->Properties->PRU Linker->File Search Path)
    • In Include library file or command file as input:
      • Add ~/ti-processor-sdk-linux-am62xx-evm-08.06.00.42/example-applications/pru-icss-6.1.0/lib/rpmsg_lib.lib
  • Apply and close
• Build the project

Copy PRU program to target and start¶

• Copy to target, fix up /lib/firmware
  • Open a Terminal View on the Local Target
    

    cd <workspace_file>/rpmsg_pru/Debug
    ssh am62x mkdir -p /lib/firmware/pru_demos
    scp rpmsg_pru.out am62x:/lib/firmware/pru_demos
    ssh am62x ln -sf /lib/firmware/pru_demos/rpmsg_pru.out /lib/firmware/am62x-pru1-fw
    

• Verify whether the rpmsg_pru kernel module is loaded
  

  ssh am62x lsmod | grep rpm
  

  • If the output does not show rpmsg_pru, then load that module.
    

    ssh am62x /sbin/insmod /lib/modules/`ssh am62x uname -r`/kernel/drivers/rpmsg/rpmsg_pru.ko
    

  • Verify whether the rpmsg_pru kernel module is loaded
    

    ssh am62x lsmod | grep rpm
    

    • Should see rpmsg_pru
• Stop and start PRU_1
  

  ssh am62x "echo stop > /sys/class/remoteproc/remoteproc3/state" 
  ssh am62x "echo start > /sys/class/remoteproc/remoteproc3/state" 
  

  • If PRU_1 is already stopped, then the stop command may produce an error like:
    

    sh: line 0: echo: write error: Invalid argument
    

  • After the start, you should see messages like this on the console
    

    [  167.824111] remoteproc remoteproc3: powering up 30078000.pru
    [  167.839411] remoteproc remoteproc3: Booting fw image am62x-pru1-fw, size 121020
    [  167.872553] virtio_rpmsg_bus virtio2: rpmsg host is online
    [  167.873267] virtio_rpmsg_bus virtio2: creating channel rpmsg-pru addr 0x1f
    [  167.880232]  remoteproc3#vdev0buffer: registered virtio2 (type 7)
    [  167.886750] rpmsg_pru virtio2.rpmsg-pru.-1.31: new rpmsg_pru device: /dev/rpmsg_pru31
    [  167.892307] remoteproc remoteproc3: remote processor 30078000.pru is now up
    

  • These messages could also be seen in the Terminal View by using:
    

    ssh am62x dmesg | tail -10
    

Manually send messages to the PRU¶

• Manually send messages to the PRU
  

  ssh am62x "echo test_message1 >/dev/rpmsg_pru31" 
  ssh am62x "echo test_message2 >/dev/rpmsg_pru31" 
  

• Manually read the messages sent back from the PRU
  

  ssh am62x cat /dev/rpmsg_pru31
  test_message1
  test_message2
  

  • You will need to hit ctrl-C to break out of the cat command.

Create an ARM program to send and receive messages from the PRU¶

• Create a new C/C++ project
  • C Managed Build, Next
  • Project Name: rpmsg_arm
  • Empty Project
  • Cross GCC
  • Next
  • Leave Debug and Release options.
  • Next
  • Cross compiler prefix: aarch64-none-linux-gnu-
  • Cross Compiler path: Browse to:
    

    ~/ti-processor-sdk-linux-am62xx-evm-08.06.00.42/linux-devkit/sysroots/x86_64-arago-linux/usr/bin
    

  • Finish
• Add source file
  • Select the rpmsg_arm project->right-mouse->Add Files...
  • Browse to
    

    ~/ti-processor-sdk-linux-am62xx-evm-08.06.00.42/example-applications/pru-icss-6.1.0/liba/Hands_on_Labs/lab_5
    

  • Select the rpmsg_pru_user_space_echo.c file. Copy file to workspace
• Turn off buffering for stdout. Without this, the output lines will not appear right away when using gdbserver.
  • Add the call to setvbuf as shown below:
    

    int main(void)
    {
        struct pollfd pollfds[1];
        int i;
        int result = 0;
    
        setvbuf (stdout, NULL, _IONBF, 0);
    

• Build the project
  • Project->Build All
• Copy program to target
  • In Terminal window
    

    cd <workspace_directory>/rpmsg_arm/Debug/
    scp rpmsg_arm am62x:.
    

• Run on target
  

  ssh am62x ./rpmsg_arm
  

  • The program sends and receives a message to and from the PRU. This is done 100 times and the messages are printed to the terminal.

Summary¶

This example has built a program for PRU_1 which receives messages from the ARM and then echoes the message back to the sender. A program for the ARM has also been built which sends 100 messages to PRU_1, reads the responses, and prints the progress to stdout.

This example uses multiple projects within one workspace where the different projects are for different processors.