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

1.10. Understanding HAL Mutual Exclusion Resources

Software device drivers can use mutual exclusion resources to control access to any data structure or peripheral register. Event flags and semaphores provide synchronization and mutual exclusion services. These resources allow only one task to access a shared piece of data at a time in a multi-threaded environment.

If the MicroC/OS-II operating system is present, its resources are used. Otherwise, the HAL provides its own set of event flags and semaphores. The HAL event flags and semaphores support device driver source code portability. The event flags and semaphores do nothing in this example.

The my_uart_driver device driver creates two semaphores and one event flag. The two semaphores are called read_lock and write_lock. my_uart_driver uses them to control access to the transmit and receive circular buffers. The event flag, called events, indicates to the software device driver when data is ready to be transmitted or received.

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