Using blocking functions, such as delay() or I/O operations within interrupt service routines, is a serious mistake that can lead to system hangs or the loss of other critical events. Performing heavy operations inside an ISR can increase the blocking time for other interrupts and violate real-time (RT) requirements. ISRs should be kept as short and deterministic as possible — their main role is to quickly capture and store information.
Our suggestion:
Minimizing ISR logic and delegating application-level processing to the main program loop or an RTOS task.

Improper management of access to shared resources—such as global variables, buffers, or hardware interfaces—can lead to race conditions, data loss, and hard-to-reproduce execution errors. In real-time systems, where multiple threads or interrupts operate concurrently, the absence of synchronization may result in extremely difficult issues to detect and debug. Neglecting safeguards in this area is one of the most common and costly mistakes in embedded code.
Our suggestion:
Using protection mechanisms for critical sections, such as semaphores, mutexes, or disabling interrupts during resource access.

Using polling — the technique of cyclically checking the status of peripheral devices or registers — leads to unnecessary CPU cycle consumption and increased energy usage, particularly in low-power systems. “Polling is easy to implement and easier to misuse. In real-time systems, it’s often the root of lost responsiveness” — as Jean Labrosse stated, founder of Micrium RTOS. This approach does not scale well in multitasking or real-time environments, as it blocks other processes and increases timing jitter.
Our suggestion:
Conducting interrupts or low-level power-saving mechanisms (such as sleep, WFI – Wait For Interrupt, or WFE – Wait For Event) to improve energy efficiency and system responsiveness.

Improperly set prescalers, clocks, or SPI/UART/I2C operation modes can lead to subtle data transmission errors. This is particularly risky when configuring input peripherals such as ADCs or digital inputs, where incorrect timing can corrupt received data. Often, the default configuration generated by the HAL does not meet the project’s actual needs.

Our suggestion:

Manual register configuration or thorough analysis of the code generated by tools like CubeMX or ConfigTool is recommended.

Lack of regression testing and debugging on actual hardware

Poor timeout and error handling

Many developers forget to check error codes and fail to implement timeouts in operations that depend on hardware or bus responses. According to VDC Research, 35% of embedded project delays are linked to undetected communication failures or lack of robust error-handling routines. Lack of separation between error detection and handling mechanisms prevents effective management of the system’s transitional states. Incorrect timeout configuration in protocols such as I²C, SPI, or UART can lead to bus lockups or improper synchronization between devices.

Our suggestion:

Applying software watchdogs, hardware timeouts, and error logging.

Structured software design with InTechHouse -from idea to implementation

Creating robust software for embedded systems is about more than just technical skills — it also requires discipline, attention to detail, and a deep understanding of both the hardware and software layers. Consciously avoiding the mistakes outlined in this article and applying structured development practices, such as proper resource management, thorough testing, and clear error handling, can ensure easier long-term maintenance of the codebase.

If you’re looking for an experienced partner in embedded software development, we invite you to collaborate with InTechHouse. Our team combines deep engineering expertise with hands-on experience in commercial and industrial projects, offering end-to-end support — from concept and design to implementation and testing. Trust experts who understand your needs and book a free consultation.

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