Guidelines for Developing a Nios II HAL Device Driver

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ID 683146
Date 6/12/2015
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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

1.12.3.1. Using the Reduced Device Drivers API Option

The Reduced device drivers option generates a #define statement for ALT_USE_SMALL_DRIVERS. To turn on this option, set hal.enable_reduced_device_drivers to true. Setting this option has the following effects on correctly-written UART device drivers:

  • Sets #define ALT_USE_SMALL_DRIVERS
  • Activates polled mode only for the UART device
  • Disables floating-point support in printf() and sprintf()
  • Configures drivers to ignore flow control.

The figure below shows excerpts from the summary.html file generated by the SBT for a BSP with reduced device drivers enabled.

Figure 22. hal.enable_reduced_device_drivers in summary.html
Note: For more information about the Reduced device drivers option, refer to "Reducing Code Footprint" in the "Developing Programs Using the Hardware Abstraction Layer" chapter and to "Reducing Code Footprint" in the "Developing Device Drivers for the Hardware Abstraction Layer" chapter of the Nios II Software Developer's Handbook.
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