Author: System on Chips

ARM Cortex-M3 Startup Script Failure in QEMU 4.2.0 The core issue revolves around the failure of a custom ARM Cortex-M3 machine to boot correctly when using the startup_ARMCM3.S startup script with QEMU version 4.2.0. The same script worked flawlessly in QEMU 2.10, but after upgrading to QEMU 4.2.0, the system fails to initialize properly. Debugging…

ARM Cortex-M0 Bootloader Challenges with SPI Flash and SRAM Mapping The ARM Cortex-M0 is a popular choice for low-power, cost-sensitive embedded systems due to its simplicity and efficiency. However, its minimalistic architecture can present challenges when implementing advanced features such as bootloading from external SPI Flash memory. One such challenge arises when attempting to load…

ARM Cortex-M7 Cache Coherency Problems During UART DMA Transfers The issue at hand involves the STM32F746 microcontroller, which utilizes an ARM Cortex-M7 core. The problem manifests when using UART in DMA mode for receiving data. The first DMA transfer works correctly, but subsequent transfers fail to update the receive buffer, despite the DMA completion callback…

ARM Cortex-MAM Mode 1 Performance Anomaly Between LPC2103 and LPC2104 The ARM LPC2103 and LPC2104 microcontrollers, while sharing many architectural similarities, exhibit a significant performance discrepancy when operating in Memory Accelerator Module (MAM) Mode 1. This anomaly manifests as the LPC2103 executing code substantially faster than the LPC2104 under identical conditions, contrary to expectations based…

ARM Cortex-M7 Cache Line Overwrite During DMA Transfers The ARM Cortex-M7 processor, with its advanced memory system and cache architecture, is widely used in embedded systems for its high performance and efficiency. However, when integrating Direct Memory Access (DMA) controllers with the Cortex-M7, developers often encounter subtle cache coherency issues that can lead to data…

ARM Cortex-M7 External RAM Integration for Sensor Data and GUI Rendering The ARM Cortex-M7 microcontroller is a powerful processor often used in embedded systems requiring high performance, such as those involving sensor data processing and graphical user interface (GUI) rendering. However, one common challenge faced by developers is the limited on-chip RAM available on many…

ARMv8 Cache Architecture and SCTLR Register Overview The ARMv8 architecture incorporates a sophisticated cache hierarchy designed to optimize performance by reducing memory access latency. The cache system typically includes Level 1 (L1) and Level 2 (L2) caches, with L1 further divided into instruction (L1 I-cache) and data (L1 D-cache) caches. The L2 cache is usually…

ARM Cortex-A72 PMU Architecture and Event Counting Overview The ARM Cortex-A72 processor is a high-performance CPU core designed for advanced applications, featuring a private Performance Monitoring Unit (PMU) for each of its four cores. The PMU is a critical component for profiling and optimizing system performance, as it allows developers to count specific hardware events…

Understanding PMU Event Counters on ARM Cortex-A72 and Cortex-R5F The Performance Monitoring Unit (PMU) in ARM Cortex-A72 and Cortex-R5F processors is a critical component for profiling and optimizing system performance. The PMU provides a set of counters that can be programmed to track specific architectural and microarchitectural events. Architectural events are those defined by the…

Flash Patching and Code Remapping in Cortex-M7: Understanding the Limitations The ARM Cortex-M7 processor, a high-performance embedded processor based on the ARMv7-M architecture, is widely used in applications requiring real-time processing and high computational throughput. One of the key features of the Cortex-M7 is its ability to execute code from tightly coupled memory (TCM) or…