Guidelines for Developing a Nios II HAL Device Driver

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ID 683146
Date 6/12/2015
Public
Document Table of Contents
Document Table of Contents x
1. Guidelines for Developing a Nios II HAL Device Driver
1. Guidelines for Developing a Nios II HAL Device Driver x
1.1. Prerequisites for HAL Device Driver Development 1.2. Developing the HAL UART Device Driver 1.3. Debugging the bit_bang_uart Project 1.4. The BitBangUartTransmit() Function 1.5. The BitBangUartReceive() Function 1.6. Creating Device Hardware Access Macros 1.7. Staging the HAL Device Driver Development 1.8. Understanding the Hardware-Specific INSTANCE and INIT Macros 1.9. Integrating a New HAL Device Driver in the BSP 1.10. Understanding HAL Mutual Exclusion Resources 1.11. Overview of Debugging Tools for HAL Device Drivers 1.12. Debugging the HAL UART Device Driver 1.13. Conclusion 1.14. Document Revision History
1.1. Prerequisites for HAL Device Driver Development x
1.1.1. Using the HAL Architecture and Services 1.1.2. Software Requirements for the Driver Example 1.1.3. HAL Device Drivers and Components
1.2. Developing the HAL UART Device Driver x
1.2.1. Preparing the bit_bang_uart Application and hal_my_uart BSP 1.2.2. Preparing the my_uart_driver Device Driver 1.2.3. Configuring the Altera_Avalon_UART Component 1.2.4. Importing Projects 1.2.5. Verifying Software Functionality 1.2.6. Preview: Customizing the Design
1.2.6. Preview: Customizing the Design x
1.2.6.1. Making Software Modifications 1.2.6.2. Making Hardware Modifications
1.12. Debugging the HAL UART Device Driver x
1.12.1. Setting Breakpoints in the my_uart_driver Device Driver 1.12.2. Setting Watchpoints in the HAL UART Device Driver 1.12.3. Reducing Driver Code and Memory Footprint 1.12.4. Interrupt Latency and Determinism 1.12.5. Debugging with the Altera Logging Functions
1.12.3. Reducing Driver Code and Memory Footprint x
1.12.3.1. Using the Reduced Device Drivers API Option 1.12.3.2. Using the Lightweight Device Drivers API Option
1.12.5. Debugging with the Altera Logging Functions x
1.12.5.1. Altera Logging Usage 1.12.5.2. Altera Logging Example
1. Guidelines for Developing a Nios II HAL Device Driver

1.12. Debugging the HAL UART Device Driver

For the next set of debugging examples, you must create a new application. For these examples, create the hello_world_my_uart application and import it to the Nios II SBT for Eclipse. Next, regenerate the files which make up the hal_my_uart BSP. This time, instead of commenting out the invocation of the macros ALTERA_AVALON_UART_INSTANCE() and ALTERA_AVALON_UART_INIT(), let the alt_sys_init() function install the Altera Avalon UART HAL device driver, after which you can inspect its operation.

The following sections show examples of placing breakpoints and watchpoints in HAL device driver source code to analyze component instance behavior.

To create and import the hello_world_my_uart project, perform the following steps:

  1. Delete the generated file public.mk from the hal_my_uart BSP. Enter the following command in the Nios II Command Shell:

    rm <my_design>/software_examples/bsp/hal_my_uart/public.mk

    Deleting these files causes the next build to regenerate the hal_my_uart BSP files, including alt_sys_init.c.

  2. Create the hello_world_my_uart application by invoking its create-this-app script. Enter the following commands:

    cd <my_design>/software_examples/app/hello_world_my_uart r ./create-this-app

    This action accomplishes several tasks:

    • Invokes the create-this-bsp script for the hal_my_uart BSP.
    • In the BSP, deletes and rebuilds generated files and object files from the previous build.
    • Builds the libhal_bsp.a BSP library in the

      <my_design> /software_examples/bsp/hal_my_uart directory.

    • Builds the hello_world_my_uart.elf file in the

      <my_design> /software_examples/app/hello_world_my_uart directory.

    • Generates a new public.mk file.
    • Sets the software device descriptors stdout, stderr, and stdin to uart1. The <my_design> /software_examples/bsp/hal_my_uart/create-this-bsp script sets up these software device descriptors by calling nios2-bsp.
    • Creates the software device driver, my_uart_driver, in the <my_design> /ip/my_uart directory, and associates it with the Altera_Avalon_UART device. The <my_design> /ip/my_uart/my_uart_sw.tcl script creates the driver and associates it with its device.
    • Sets the software device driver called my_uart_driver to the component instance named uart1. The <my_design> /software_examples/bsp/hal_my_uart/ hal_my_uart.tcl script, passed to nios2-bsp, sets the driver to uart1.
    • Regenerates alt_sys_init.c by invoking of ALTERA_AVALON_UART_INIT().
      Note: You can invoke nios2-bsp with the --debug parameter, which displays verbose information about the construction steps in this section. The --debug parameter can be very useful for finding errors in the construction of the relevant Tcl scripts and command shell scripts.
  3. Import the hello_world_my_uart application to the Nios II SBT for Eclipse as described in the section Importing Projects in Steps 2 through 8, substituting the hello_world_my_uart application for the bit_bang_uart application. It is not necessary to re-import the BSP.

Section Content
Setting Breakpoints in the my_uart_driver Device Driver
Setting Watchpoints in the HAL UART Device Driver
Reducing Driver Code and Memory Footprint
Interrupt Latency and Determinism
Debugging with the Altera Logging Functions

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