hello_vsi

Hello VSI example

This example uses the Virtual Streaming Interface (VSI)) to simulate a peripheral sensor. The example sensor will send data in form of bytes to the application running on an AVH FVP Model. The virtual peripheral is controlled by a python script arm_vsi0.py that reads the data from a text file called intdata.txt. This is a minimal example of how to use Arm VSI, and you can modify the python script and the sensor driver in order to match your use case.

Application operation

The application receives sensor data from the intdata.txt file and prints the values to the console. For each loop, the application will wait until DMA block is filled, at that point the application will proceed to copy the data from a data buffer and print out to the console. When end of intdata.txt file is reached, the operation loop is stopped.

You can modify the streaming and driver operation using data and DMA parameters in app.c file.

The application supports Corstone-320, Corstone-315, Corstone-310 and Corstone-300 targets, and can be compiled with Arm Compiler 6 or GCC.

See Application flows below for additional details.

Build

Use the cbuild tool or an IDE to build the application project in csolution format (see the main README).

The build context is contructed as flow type (such as .event) and target type (such as +Corstone_315). To compile with AC6 use --toolchain AC6 and for GCC the --toolchain GCC option with the cbuild command. For example:

To build the project for Corstone-315 target with GCC compiler use:

cbuild hello_vsi.csolution.yml --packs --rebuild --toolchain GCC --context .event+Corstone_315

To build with the gated fetch flow for the Corstone-310 target and Arm Compiler 6:

cbuild hello_vsi.csolution.yml --packs --rebuild --toolchain AC6 --context .gated+Corstone_310

Run

To run the application from command line, use corresponding AVH FVP and provide the path to the binary image as well as the VSI python scripts. Also see the main README for details.

For example:

To run on the Corstone-315 the event-based firmware built with GCC compiler, with exit after running 40 seconds (wall-time), use:

FVP_Corstone_SSE-315 -a ./out/hello_vsi/Corstone_315/event/GCC/hello_vsi.elf -C mps4_board.v_path=./source/vsi/data_sensor_py/ --timelimit 40

For a target Corstone-310 with gated fetch flow built with Arm Compiler 6 and exit after 60 seconds of execution:

FVP_Corstone_SSE-310 -a ./out/hello_vsi/Corstone_310/gated/AC6/hello_vsi.axf -C mps3_board.v_path=./source/vsi/data_sensor_py/ --timelimit 40

Application flows

The sections below explain the application flows for the supported build types.

Event Driven Flow

Sensor data is continuously streamed from the sensor. When DMA block is filled with data a sensor event is triggered, the block is copied and application prints obtained values into the console.

Use .event as the build type, followed by the target platform.

sequenceDiagram
    participant Main
    participant Driver
    participant Peripheral
        Main->>+Driver: Init Driver 
        Driver->>+Peripheral: Init Peripheral
    loop Every sample
        Main->>+Main: Wait for Data Event
        Peripheral->>+Driver: Stream Data
        Driver->>+Main: Data Event Interrupt
        Main->>+Driver: Call Get_Data
        Driver->>+Main: Copy Data
        Main->>+Main: Print Data
    end

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Gated fetch Flow

Sensor data is fetched only when requested so by the application. The peripheral will be paused between each data fetch.

Use .gated as the build type, followed by the target platform.

sequenceDiagram
    participant Main
    participant Driver
    participant Peripheral
        Main->>+Driver: Init Driver 
        Driver->>+Peripheral: Init Peripheral
    loop Every sample 
        Main->>+Driver: Call Get_Data
        Driver->>+Driver: Wait for new data
        Peripheral->>+Driver: Stream Data Interupt
        Driver->>+Main: Copy Data
        Main->>+Main: Print Data
    end

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