Architectures and Processors

NVIC Set Enable and Clear Enable Register Behavior in Cortex-M4 The behavior of the Nested Vectored Interrupt Controller (NVIC) in ARM Cortex-M4 processors, particularly regarding the Set Enable (ISER) and Clear Enable (ICER) registers, can be a source of confusion for developers. When enabling an interrupt using the NVIC_ISER register, it is observed that the…

Cache and MMU Enable/Disable Sequence in Bootloader Initialization When developing a custom bootloader for an ARM Cortex-A9 processor, such as the one found in the NXP i.MX6 DualLite, managing the caches and Memory Management Unit (MMU) is critical to ensure proper system initialization. The bootloader must initialize a large block of memory (e.g., 50 MB)…

Cortex-A7 L1 Data and Unified Cache Disablement in AMP Mode The ARM Cortex-A7 processor, widely used in embedded systems for its balance of performance and power efficiency, exhibits a unique behavior when operating in Asymmetric Multiprocessing (AMP) mode. Specifically, when the SMP (Symmetric Multiprocessing) bit in the ACTLR (Auxiliary Control Register) is cleared to enable…

ARM Cortex-R Vector Table Transition from High to Low Address When working with ARM Cortex-R series processors, transitioning between vector tables located at different memory addresses (e.g., from high vectors at 0xFFFF0000 to low vectors at 0x00000000) is a critical operation that requires careful handling of system registers and memory barriers. The process involves modifying…

ARM Cortex-M7 Semihosting File I/O Failures in DS-5 Semihosting is a mechanism that allows ARM-based embedded systems to communicate with a host computer for debugging and development purposes. It enables the target device to use the host’s resources, such as file I/O, console input/output, and other system services. However, when implementing semihosting on an ARM…

Cortex-M0 ROM-to-RAM Program Counter Transition Challenges The Cortex-M0 microcontroller unit (MCU) is a widely used ARM processor core known for its simplicity and efficiency in embedded systems. One common design scenario involves executing firmware from Read-Only Memory (ROM) upon power-up, followed by a transition to executing firmware from Random-Access Memory (RAM). This transition is typically…

DDR3 RAM Compatibility with ARM Cortex-A9 and Memory Controller Integration The compatibility of DDR3 RAM with an ARM Cortex-A9 processor or any ARMv7-A architecture-based system is not a direct relationship between the processor core and the memory itself. Instead, it is mediated by the memory controller integrated within the System on Chip (SoC). The ARM…

NEON Library Integration Challenges on i.MX6 Cortex-A9 The integration of NEON libraries into an existing video shot detection algorithm on the i.MX6 Cortex-A9 processor presents a multifaceted challenge. The i.MX6 Cortex-A9, a dual-core ARM processor, is widely used in embedded systems for its balance of performance and power efficiency. However, optimizing complex nested loops in…

Cortex-A53 ACE Interface and AXI-4 Interconnect Compatibility Challenges The Cortex-A53 processor, a widely used ARM core in embedded systems, supports two primary master interfaces: ACE (AXI Coherency Extensions) and CHI (Coherent Hub Interface). These interfaces are designed to facilitate coherent data sharing in multi-core systems. However, when integrating the Cortex-A53 with an AXI-4 interconnect, compatibility…

Understanding the cmse_check_address_range Function and Its Return Value The cmse_check_address_range function is a critical component in ARM TrustZone implementations, particularly when dealing with secure and non-secure memory interactions. This function is designed to verify whether a given memory address range is accessible from the non-secure state. The function takes a pointer to a memory address…