A Guide to Comparing Low-Level and HAL Programming in STM32

1. Bare-metal programming, or low-level programming

Write the code that communicates directly with the hardware is known as low-level programming. For the STM32, this entails configuring the microcontroller’s registers directly, without the use of abstraction layers.

Low-Level Programming Benefits

Total Control: Having total control over the hardware is the main advantage of low-level programming. To set up peripherals, timers, interrupts, and other features, you can directly modify the microcontroller’s registers.
Optimized Performance: The code can be greatly optimized for speed, size, and performance because there is no abstraction. In real-time systems where performance is crucial, this is particularly crucial.

Reduced Code Size: Because you are not employing a large abstraction layer that adds overhead, low-level programming typically produces smaller binaries.

Flexibility: Without being limited by preset libraries or abstractions, developers can create unique peripheral handling and functionality.

Low-Level Programming Complexity Drawbacks:

Complexity: Writing low-level code necessitates a thorough comprehension of the registers, peripherals, and architecture of the microcontroller. For novices in particular, it might be more challenging and time-consuming.
Code Portability: It can be difficult to transfer the code to different microcontrollers or even different STM32 generations because it is closely linked to the particular microcontroller and its registers.
Increased Development Time: Writing and testing drivers and initialization code for peripherals is a common task for developers, which can add time to the development process.

Example: Using Low-Level Programming to Blink an LED
An STM32 microcontroller’s GPIO pin PA5 can be used to flash an LED using the following low-level code example:

This code toggles an LED’s state by directly modifying the STM32’s hardware registers. The system clock, GPIO settings, and other low-level functions need to be manually configured.

2. Hardware Abstraction Layer (HAL) Programming

The Hardware Abstraction Layer, or HAL, is provided by STM32 to facilitate communication with the microcontroller. The HAL speeds up and simplifies development by abstracting away hardware-level details and offering a collection of functions for configuring and controlling peripherals.

HAL Programming Benefits

Easy to Use: By offering high-level capabilities, HAL makes peripheral configuration simpler. These features handle peripheral startup, configuration, and control without necessitating an understanding of hardware registers.

Portability: By abstracting away the hardware specifics, HAL functions increase the code’s adaptability to several STM32 families (such as STM32F4, STM32F7, and STM32H7). With only few modifications, you may effortlessly transfer your project from one STM32 series to another.

Faster Development: Developers can concentrate more on the application logic because the HAL functions handle a large number of the hardware specifics. Development time is shortened as a result.

Built-In Features: The HAL has a number of built-in features, such as middleware for communication protocols (USB, Ethernet, etc.), interrupt management, and DMA support.

Problems with HAL Programming

Reduced Authority: HAL makes development easier, but it gives you less precise hardware control. Not all peripheral operations can be optimized or fine-tuned by you.

Performance Overhead: Because of the abstraction layer, using the HAL may result in some performance overhead. For time-sensitive applications, this might not be the best option.

Greater Code Size: Although useful, the HAL functions add dependencies and additional code that might make the total size of the firmware.

Example: Using HAL to blink an LED
This is an example of the same LED flashing that makes use of the STM32 HAL library:

In this model, the HAL_GPIO_Init() capability designs the GPIO pin, and HAL_GPIO_TogglePin() is utilized to flip the Drove. The defer capability is worked on utilizing HAL_Delay(). The hidden register designs are dealt with consequently by the HAL library.

3. Key Contrasts Between Low-Level and HAL Programming

4. When to Utilize Low-Level Programming versus HAL

Utilize Low-Level Programming when:

• You want the very best presentation or proficiency (e.g., continuously applications).
• You are working with explicit equipment arrangements or need admittance to equipment enlists that are not uncovered by the HAL.
• You are dealing with a custom board and need full command over the peripherals.
• The application should limit the memory impression.

Use HAL Programming when:

• You need quicker improvement with insignificant arrangement and setup.
• You are building a more broadly useful application and needn’t bother with the outrageous presentation enhancements.
• Compactness across various STM32 families is really important.
• You are chipping away at complex applications that require progressed peripherals (USB, Ethernet, and so on) or middleware.

5. End

Both Low-Level and HAL Programming have their place in STM32 advancement. The decision between them relies upon the undertaking necessities, designer experience, and execution objectives. For applications where speed, memory advancement, and complete equipment control are fundamental, low-level writing computer programs is the best approach. Be that as it may, assuming fast turn of events and movability are vital, HAL programming gives a simpler and more viable methodology. Numerous engineers utilize a half and half methodology, consolidating the two strategies in light of the particular requirements of the undertaking.