ARM Cortex-A Series Cache Coherency and ACE Protocol Behavior The ARM Cortex-A series processors utilize the ACE (AXI Coherency Extensions) protocol to maintain cache coherency across multiple masters in a system. Cache coherency is critical in multi-core systems where multiple processors or DMA controllers may access shared memory. The ACE protocol ensures that all masters…
ARM Non-Reordering Device Memory and IMPLEMENTATION DEFINED SIZE The ARM architecture, particularly in the context of ARMv8, provides a robust framework for memory management, including the handling of device memory. One of the key attributes of device memory is the non-Reordering (nR) attribute, which ensures that memory accesses to a single peripheral occur in the…
ARM Cortex-M33 Firmware Update Over-the-Air (OTA) Architecture The LPC55S69 microcontroller, based on the ARM Cortex-M33 core, is a powerful and secure platform for embedded applications. One of its advanced use cases is enabling Over-the-Air (OTA) firmware updates, which allow remote updating of the device’s firmware without physical access. Implementing OTA updates on the LPC55S69 involves…
ARM Cortex-A53 Exception Level Transition Failure from EL2 to EL1 The ARM Cortex-A53 processor, part of the ARMv8-A architecture, supports multiple exception levels (ELs) that provide hierarchical privilege and security isolation. Transitioning between these exception levels is a critical operation, especially during boot sequences or when switching between hypervisor and guest operating systems. A common…
ARM Cortex-M3 Precise Bus Fault During Timer 2 ISR Execution The issue at hand involves a Precise Bus Fault occurring during the execution of a Timer 2 Interrupt Service Routine (ISR) on an ARM Cortex-M3 processor. The fault manifests when the ISR attempts to access a memory location to increment a global counter variable. The…
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-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-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 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-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…