Architectures and Processors

ARM Cortex-A53 Stage 2 Translation Setup and EL2 Hangs When enabling stage 2 translation on an ARM Cortex-A53 processor, such as the one found in the Raspberry Pi 3B+, the system may hang during the configuration process in Exception Level 2 (EL2). This issue typically arises when setting up the Virtualization Translation Table Base Register…

Cortex-M33 FPU Underflow and Input Denormal Exception Flag Conditions The Cortex-M33 Floating Point Unit (FPU) is a critical component for handling floating-point arithmetic in embedded systems. It provides hardware support for single-precision floating-point operations, which are essential for applications requiring high precision and performance. However, the FPU can generate specific exception flags under certain conditions,…

ETM Trace Data Synchronization Errors in Keil IDE The Embedded Trace Macrocell (ETM) in ARM Cortex-M4 processors is a powerful tool for real-time debugging and trace analysis. However, signal integrity issues on the ETM trace bus can lead to synchronization errors, particularly when interfacing with debug tools like Keil IDE. These errors manifest as "Trace…

ARMv8 Exception Level and Execution State Transition Challenges The ARMv8 architecture introduces a sophisticated exception level (EL) model and execution state (AArch32 and AArch64) framework, which provides flexibility but also complexity when transitioning between different privilege levels and execution states. A common scenario in baremetal systems involves starting execution in AArch64 at EL3 during reset…

ARM Cortex-M4 Inline Assembly Syntax Errors in sysctl.c The issue at hand revolves around inline assembly syntax errors encountered while working with the ARM Cortex-M4 processor, specifically within the sysctl.c file. The user was attempting to implement UART polling using FreeRTOS on the TM4C1294XL microcontroller when they encountered compilation errors related to the inline assembly…

Secure World Variable Allocation in ARM TrustZone-M When working with ARM TrustZone-M on Cortex-M processors, one of the critical tasks is ensuring that sensitive data, such as cryptographic keys or secure application state, is stored in memory that is only accessible to the Secure World. This is particularly important for maintaining the integrity and confidentiality…

ARM Cortex-M33/M35P Bit Banding Absence in ARMv8-M Architecture The ARM Cortex-M33 and Cortex-M35P processors, based on the ARMv8-M architecture, do not support the bit-banding memory model, a feature that was available in earlier ARM Cortex-M processors such as the Cortex-M3 and Cortex-M4. Bit banding allows individual bits in memory to be directly accessed and modified…

GPIO Functionality in CMSIS-Driver and Standard Naming Conventions The ARM Cortex-M microcontrollers are widely used in embedded systems due to their efficiency, scalability, and robust ecosystem. One of the key components of this ecosystem is the Cortex Microcontroller Software Interface Standard (CMSIS), which provides a standardized hardware abstraction layer for Cortex-M processors. However, a common…

ARM Cortex-M33 IMPRECISERR Default Implementation and Documentation Ambiguity The ARM Cortex-M33 processor, a member of the ARMv8-M architecture, introduces several advanced features, including enhanced fault handling mechanisms. One such mechanism is the IMPRECISERR fault, which is part of the Configurable Fault Status Register (CFSR) within the System Control Block (SCB). The IMPRECISERR fault is specifically…

Cortex-M7 SPI Peripheral Register Base Address Confusion The Cortex-M7 is a high-performance microcontroller core designed by ARM, widely used in embedded systems for its advanced features such as a dual-issue pipeline, floating-point unit, and cache memory. However, one common source of confusion among developers working with Cortex-M7-based microcontrollers, such as the NXP i.MX RT1060 used…