Author: System on Chips

ARM Cortex-R52+ Data Abort Triggered by CPSR Write Operation The Cortex-R52+ processor is a high-performance, real-time capable core designed for safety-critical applications. It is common to encounter complex hardware-software interaction issues when working with such architectures, especially when dealing with low-level register manipulations. One such issue arises when executing the MSR CPSR_cx, #0x1F instruction, which…

ARM Cortex-A725 CASAL Instruction Fault in EL1 with MMU Enabled The issue revolves around a data abort exception (0x96000035) triggered during the execution of the CASAL (Compare and Swap Atomic Local) instruction on an ARM Cortex-A725 processor. The exception occurs in EL1 (Exception Level 1) with the MMU (Memory Management Unit) enabled, and the fault…

ARM Cortex-M Interrupt Handling and Memory Barrier Requirements In ARM Cortex-M processors, ensuring that interrupts are handled immediately after being pending is critical for real-time systems. The ARM architecture provides two memory barrier instructions, Data Synchronization Barrier (DSB) and Instruction Synchronization Barrier (ISB), to manage the order of memory operations and instruction execution. The DSB…

ARM Cortex-A7 and Cortex-A9 Processors with Gigabit Ethernet: Key Considerations When selecting an ARM processor with Gigabit Ethernet support, several factors must be considered to ensure the chosen processor meets the requirements of the intended application. The primary considerations include the processor’s architecture, the availability of a free Integrated Development Environment (IDE), and the overall…

FIQ Exception with INTID 1023 During Mixed IRQ and FIQ Handling The ARM Cortex-R52 processor, when configured with the Generic Interrupt Controller (GIC) version 3, can encounter a scenario where a Fast Interrupt Request (FIQ) exception is taken, but the Interrupt Acknowledge Register (ICC_IAR0) returns an Interrupt ID (INTID) of 1023. This value is a…

Interrupt Masking Ineffectiveness in AArch64 Exception Routing In ARM architectures, particularly in AArch64, the handling of interrupts across different Exception Levels (ELs) is a critical aspect of system design. A common issue arises when interrupts, despite being masked at a lower Exception Level (e.g., EL1), are still signaled and cause exceptions to be taken at…

ARM NEON and SVE High-Bit Packing Challenges in 64-Byte Vectors The task of packing the high bit of every byte in a 64-byte vector into a compact integer mask is a common operation in high-performance computing, particularly in image processing, compression, and machine learning workloads. On Intel architectures, this operation is efficiently handled by AVX-512…

Understanding ETM Trace Data Flush Behavior in Cortex-M33 The Embedded Trace Macrocell (ETM) in ARM Cortex-M33 processors is a powerful tool for real-time instruction and data tracing, enabling developers to capture and analyze program execution flow. However, a critical issue arises when the trace data generated just before a program break is less than 16…

ARM Cortex-M0+ Debug Halting and Lockup During RDP Level 1 The STM32G030 microcontroller, based on the ARM Cortex-M0+ core, exhibits unexpected behavior when operating under Readout Protection (RDP) level 1. Specifically, attempts to access RAM or peripheral regions via the Serial Wire Debug (SWD) interface result in the CPU halting and eventually locking up. This…

ARM Neon MMLA Instructions and Their Data Layout Challenges The ARM Neon Matrix Multiply-Accumulate (MMLA) instructions, such as SMMLA, are powerful tools for accelerating matrix operations in embedded systems. These instructions are designed to perform signed 8-bit integer matrix multiplications, specifically multiplying a 2×8 matrix by an 8×2 matrix to produce a 2×2 matrix of…