Using __get_IPSR() to Identify Interrupt Sources in a Shared ISR The Cortex-M0+ microcontroller, like other ARM Cortex-M processors, supports a flexible interrupt handling mechanism that allows developers to use a single Interrupt Service Routine (ISR) for multiple interrupt sources. This approach is particularly useful when implementing an "OS-like" function that centralizes interrupt handling, performs privilege…
ARM Cortex-M Dual Stack Pointer Architecture and Context Switching Challenges The ARM Cortex-M architecture employs a dual stack pointer mechanism, utilizing both the Main Stack Pointer (MSP) and the Process Stack Pointer (PSP). This design is pivotal for separating kernel and user tasks, enhancing system reliability and security. The MSP is typically used for exception…
SWD Protocol Initialization and IDCODE Read Success but MEM-AP Access Failure The core issue revolves around the successful initialization of the Serial Wire Debug (SWD) protocol and the ability to read the IDCODE register on an ARM Cortex-M0 processor, but subsequent failure to access the Memory Access Port (MEM-AP). The IDCODE register read operation returns…
ARM Cortex-M0+ Linker Errors Due to Missing System Call Implementations When attempting to cross-compile a simple "Hello World" application for an ARM Cortex-M0+ target using the GNU Arm Embedded Toolchain, you may encounter linker errors indicating undefined references to system calls such as _exit, _sbrk, _write, _close, _lseek, _read, _fstat, and _isatty. These errors arise…
MPU Configuration and Hard Fault Trigger During Enable The ARM Cortex-M3 Memory Protection Unit (MPU) is a critical component for ensuring memory safety and access control in embedded systems. However, enabling the MPU can sometimes lead to unexpected hard faults, especially if the configuration is incorrect or incomplete. In this scenario, the hard fault is…
Bare-Metal Code Development for ARM Cortex-A53 and Cortex-M4 in iMX8M Mini Developing bare-metal code for the iMX8M Mini, which features a dual-core ARM Cortex-A53 and a Cortex-M4, presents unique challenges, especially in avionics applications where certification and reliability are paramount. The Cortex-A53, being a high-performance application processor, and the Cortex-M4, a real-time microcontroller, require different…
ARM Cortex-M3 64-bit Division Performance Challenges The ARM Cortex-M3 is a widely used 32-bit microcontroller core that excels in embedded systems due to its balance of performance, power efficiency, and cost-effectiveness. However, one of its limitations is the lack of native support for 64-bit arithmetic operations, particularly division. When performing 64-bit division on the Cortex-M3,…
ARM Cortex-M33 BX Instruction Behavior in Secure State The ARM Cortex-M33 processor, based on the ARMv8-M architecture, introduces a robust security model that partitions code execution into Secure and Non-Secure states. This partitioning is enforced by the Memory Protection Unit (MPU) and the Security Attribution Unit (SAU), which define memory regions as Secure or Non-Secure….
ARM Cortex-M TrustZone Memory Access Vulnerabilities In ARM Cortex-M systems utilizing TrustZone technology, one of the most critical security challenges is ensuring that Non-Secure (NS) code cannot maliciously access Secure (S) memory regions. This issue arises due to the dual mapping of memory regions in both Secure and Non-Secure address spaces, which can lead to…
ARM Cortex-A9 ETB and Intel LBR: Functional Comparison and Use Cases The Intel Last Branch Recording (LBR) feature and ARM’s Embedded Trace Buffer (ETB) serve similar purposes in the context of instruction-level monitoring and debugging, but they differ significantly in implementation, capabilities, and overhead. Intel’s LBR is a hardware feature that records the most recent…