Architectures and Processors

Cortex-R5 Outperforming Cortex-A9: Clock Cycles vs Execution Time Mismatch The observed performance discrepancy between the ARM Cortex-R5 and Cortex-A9 processors, where the Cortex-R5 completes a computation in half the time despite using significantly more clock cycles, is a multifaceted issue rooted in architectural differences, memory subsystem configurations, and potential misconfigurations in the Cortex-A9 setup. The…

Cortex-M4 Processor State Preservation Requirements During Power-Down The Cortex-M4 processor, like many ARM cores, is designed for low-power applications where power-down and resume functionality is critical. When powering down the Cortex-M4 while retaining system RAM, the processor state must be saved to ensure a seamless restoration upon resumption. This involves preserving not only the core…

Cortex-A17 Cache Flush Latency: Understanding the Performance Bottleneck The flush_cache_all() function on the Cortex-A17 core, operating at 1.25 GHz with a 32 KB I-cache, 32 KB D-cache, and 256 KB L2 cache, is reported to consume over 200 microseconds. This latency is significant, especially in real-time or performance-critical applications where cache maintenance operations must be…

ARM Cortex-M Toolchain Confusion: GNU-ARM-GCC vs. ARM-None-EABI-GCC The ARM Cortex-M series of microcontrollers is widely used in embedded systems due to its efficiency, low power consumption, and robust performance. However, one of the most common sources of confusion for developers new to the ARM ecosystem is the variety of toolchains available for compiling and debugging…

ARM Cortex-A55 DSU P-Channel PACCEPT/PDENY Signal Behavior in Multi-Core Power Management The ARM Cortex-A55 is a highly efficient mid-range CPU core designed for power-sensitive applications, often integrated into multi-core configurations. One of its key features is the DynamIQ Shared Unit (DSU), which manages shared resources and power states across multiple cores. The DSU implements the…

SPI Master Mode Initialization and Clock Configuration Issues The core issue revolves around the SPI peripheral on the STM32F407 microcontroller not functioning as expected in master mode. Specifically, while the chip select (CS) pin toggles correctly, no data is observed on the MOSI or SCLK lines. This suggests a fundamental misconfiguration in one or more…

Cortex-M4 Bootloader Infinite Loop and Hard Fault Generation The issue at hand involves a Cortex-M4 slave core in a multicore system failing to boot reliably. The master core loads the application for the Cortex-M4 slave core, which is expected to execute the boot file (c_int00) and then jump to the main application. However, the system…

ARM Cortex-A53 Neon Intrinsics Performance Issues at O3 Optimization Issue Overview: Neon Intrinsics Code Performance and Compiler Behavior The core issue revolves around the performance and behavior of Neon intrinsics code when compiled with GCC (aarch64-none-elf-gcc) at the highest optimization level (-O3) for the ARM Cortex-A53 processor. The user is working on a bare-metal application…

Developing Middleware Firmware for Multi-Vendor ARM Cortex-M Devices Developing middleware firmware that operates seamlessly across multiple ARM Cortex-M microcontrollers from different vendors, such as STMicroelectronics (STM32), NXP (LPC), and Cypress (PSoC), presents a unique set of challenges. The primary goal is to create a codebase that abstracts hardware differences while maintaining compatibility with peripherals like…

ARM Cortex-A53 Cache Maintenance Operations: DCIMVAC vs. DCCIMVAC The ARM Cortex-A53 processor, a widely used core in embedded systems, implements sophisticated cache maintenance operations to ensure data consistency and system performance. Two such operations, DCIMVAC (Data Cache Invalidate by Modified Virtual Address to PoC) and DCCIMVAC (Data Cache Clean and Invalidate by Modified Virtual Address…