Architectures and Processors

ARM Cortex-M33 Secure Memory Exposure via JTAG and UART The ARM Cortex-M33 processor, with its TrustZone technology, is designed to provide robust security features for embedded systems. However, the security of the system can be compromised if the debug authentication controls are not properly configured or if the software implementation is flawed. Specifically, the JTAG…

ARMv8-A Virtual-to-Physical Translation Inconsistencies Under High Interrupt Load In ARMv8-A architectures, the translation of virtual addresses to physical addresses is a critical operation, especially in systems with a 1:1 mapping between virtual and physical memory spaces. The Address Translation (AT) instruction, combined with the Physical Address Register (PAR_EL1), is commonly used to perform this translation….

AXI 4.0 Protocol Byte Count Calculation Challenges The AXI 4.0 protocol is a widely used interface standard for high-performance embedded systems, particularly in ARM-based designs. One of the critical aspects of working with AXI 4.0 is accurately calculating the number of bytes transferred during a transaction. This calculation becomes particularly complex when dealing with incremental…

ARMv7-A MPU Unified Region Base Address Misinterpretation The ARMv7-A architecture, widely used in embedded systems, incorporates a Memory Protection Unit (MPU) designed to enforce memory access permissions and enhance system security. A common misconception arises regarding the functionality of the Unified Region Base and Size registers within the MPU. Specifically, developers often assume that the…

ARM AHB-Lite Master Definition and Role in SOC Design The Advanced Microcontroller Bus Architecture (AMBA) Advanced High-performance Bus Lite (AHB-Lite) is a widely used on-chip communication protocol for high-performance systems, particularly in ARM-based microcontrollers and System-on-Chip (SOC) designs. A fundamental concept in AHB-Lite is the distinction between masters and slaves. A master in the AHB-Lite…

AHB5 Architecture and the Absence of SPLIT and RETRY Responses The Advanced High-performance Bus (AHB) protocol, developed by ARM, has undergone several iterations since its inception. The latest version, AHB5 (part of the AMBA 5 specification), has evolved significantly from its predecessors, particularly in its handling of bus transactions and responses. One notable change in…

Cortex-A53 Pipeline Architecture and Stage Breakdown The Cortex-A53 processor, a member of ARM’s Cortex-A series, is designed with an 8-stage pipeline to balance performance and power efficiency. The pipeline stages are meticulously crafted to handle instruction processing with minimal stalls and maximum throughput. Each stage has a specific role in the instruction execution process, and…

ARM Cortex-A9 Trace Decompressor Misalignment with Barrier Instructions and Synchronization Primitives When developing a trace decompressor for an ARM Cortex-A9 system, particularly on an Altera Cyclone V platform with CoreSight PFT 1.0, a critical issue arises when parsing the program image to extract waypoint information. The decompressor encounters misalignment in the decoded stream when treating…

ARM Cortex-A53 Instruction Cycle Counting: Excluding Memory and Cache Overheads When working with the ARM Cortex-A53 processor, accurately measuring the cycle count of instructions while excluding memory and cache operations is a common requirement for performance analysis and optimization. The Cortex-A53, being a highly efficient 64-bit ARMv8-A core, is widely used in embedded systems and…

Fixed-Point Arithmetic Challenges on Cortex-M4 Without FPU When working with ARM Cortex-M4 microcontrollers that lack a Floating-Point Unit (FPU), such as the nrf52810, developers often face significant challenges in performing efficient fractional and trigonometric calculations. The absence of an FPU means that floating-point operations are emulated in software, leading to increased computational overhead and slower…