Architectures and Processors

ARM Cortex-A55 PMU Limitations in Counting Non-Cacheable Accesses The ARM Cortex-A55 processor, a member of the ARMv8-A architecture family, is widely used in embedded systems for its balance of performance and power efficiency. One of its key features is the Performance Monitoring Unit (PMU), which provides hardware counters to track various events, such as cache…

NMI Risks in Bootloader Code on ARM Cortex-M Processors Non-Maskable Interrupts (NMIs) are a critical aspect of ARM Cortex-M processors, designed to handle high-priority events that cannot be ignored, even when regular interrupts are disabled. In the context of bootloader code, NMIs present a unique challenge because bootloaders typically operate in a minimalistic environment with…

ARM Cortex-M Interrupt Timing and Square Wave Generation Requirements The core issue revolves around implementing an interrupt handler in assembly language for an ARM Cortex-M processor to generate a square wave output. The interrupt occurs at 500-microsecond intervals, and the handler must toggle a specific bit at the memory-mapped I/O location labeled GEN. The square…

ARM Cortex-M4 Time Profiling Challenges Without ETM Support The ARM Cortex-M4 microcontroller, such as the LPC4370, is widely used in real-time applications due to its balance of performance and power efficiency. However, one common challenge developers face is accurately measuring the execution time of specific functions or code segments, especially when the microcontroller lacks Embedded…

ARM Cortex-A9 Main TLB Miss Counting Challenges The ARM Cortex-A9 processor, a widely used core in embedded systems, employs a two-level Translation Lookaside Buffer (TLB) architecture to optimize virtual-to-physical address translation. The TLB hierarchy consists of micro TLBs (uTLBs) and a main TLB. While the uTLBs are small, fast caches for recently used translations, the…

ARM MMU Configuration: AF and AP Attributes in Memory Management The ARM Memory Management Unit (MMU) is a critical component in modern ARM architectures, enabling virtual memory management, memory protection, and access control. Two key attributes in the MMU configuration are the Access Permission (AP) and the Access Flag (AF). These attributes play distinct roles…

Big-Endian Support Challenges in ARMv7-R Toolchain Configuration The ARM architecture, particularly the ARMv7-R profile, is widely used in real-time embedded systems due to its deterministic performance and robust feature set. However, one of the persistent challenges in configuring toolchains for ARMv7-R processors, such as the TI TMS570 series, is the lack of out-of-the-box support for…

FPU Version Variability Across ARM Cortex-M Microcontrollers The Floating-Point Unit (FPU) is a critical component in ARM Cortex-M microcontrollers, enabling efficient handling of floating-point operations. However, the FPU version can vary significantly across different Cortex-M cores and microcontroller families, such as the Tiva C Launchpad (TM4C123GH6PM), STM32F407, and STM32F446RE. This variability often leads to confusion…

ARM Cortex-R5 ATCM Read Aborts with Synchronous Parity or ECC Error The issue at hand involves a Data Abort exception occurring during read operations from the ATCM (Tightly Coupled Memory) in an ARM Cortex-R5 processor. The abort is triggered specifically when attempting to read from certain addresses within the ATCM, while write operations to the…

Understanding the AXI4 Lite Protocol and Combinatorial Path Constraints The AXI4 Lite protocol, a subset of the Advanced Microcontroller Bus Architecture (AMBA) AXI4 specification, is designed for simple, low-throughput communication between components in a system-on-chip (SoC). It is widely used in embedded systems due to its simplicity and efficiency. However, one of the critical design…