Architectures and Processors

ARM Cortex-R5F Return Stack Access Limitations for Call Tree Reconstruction The ARM Cortex-R5F processor, like many ARM cores, incorporates a hardware return stack to optimize function call and return operations. This return stack is typically a small, fast memory structure embedded within the processor core, designed to store return addresses for the most recent function…

Secure and Non-Secure Interrupt Priority Mapping in ARMv8 In ARMv8 architectures, the handling of interrupt priorities between secure and non-secure states is a critical aspect of system design, especially when the Priority Inversion Secure (PRIS) bit in the Application Interrupt and Reset Control Register (AIRCR) is set. The PRIS bit remaps the priority of non-secure…

Cortex-M3 Vector Table Initialization and Memory Map Constraints The ARM Cortex-M3 processor, like other Cortex-M series processors, relies on a predefined memory map and a fixed initial vector table address to ensure proper boot-up and execution of firmware. The vector table is a critical data structure that contains the initial stack pointer value and the…

Cortex-M3 Boot Process and Memory Mapping Constraints The Cortex-M3 processor, like many embedded systems, relies on a specific memory map to function correctly. The boot process begins with the processor fetching the initial stack pointer and reset vector from specific memory addresses. By default, these addresses are located at the beginning of the memory map…

HREADYOUTS Signal Behavior During AHB-to-AHB-APB Asynchronous Transfers The HREADYOUTS signal in the AHB-to-AHB-APB asynchronous bridge IP plays a critical role in ensuring proper synchronization and data transfer between two AHB buses operating in different clock domains. When a transmission starts, the HREADYOUTS signal drops to 0, indicating that the bridge is not ready to accept…

Cortex-R5 AXI Peripheral Bus Architecture and Routing Mechanism The Cortex-R5 processor features a sophisticated AXI (Advanced eXtensible Interface) bus architecture designed to optimize peripheral access and system performance. The AXI peripheral bus is divided into two distinct interfaces: the LLPP (Low Latency Peripheral Port) Normal AXI interface and the LLPP Virtual AXI interface. These interfaces…

ARMv7-A Cache Maintenance Overhead in Large Buffer Scenarios In ARMv7-A architectures, cache maintenance operations are critical for ensuring data consistency between the CPU cache and main memory, especially in scenarios involving Direct Memory Access (DMA) or large memory buffers. The primary issue arises when dealing with large memory buffers, such as framebuffers for display controllers…

PendSV Preemption Behavior During Priority Adjustment in High-Priority ISRs The behavior of the PendSV (Pendable Service Call) exception in ARM Cortex-M4 and Cortex-M7 processors when its priority is dynamically adjusted within a high-priority Interrupt Service Routine (ISR) is a nuanced topic. This scenario arises when a high-priority ISR triggers a PendSV exception, sets it to…

ARM Cortex-M23/M33 FVP Startup Parameter Configuration for TF-M The Trusted Firmware-M (TF-M) is a secure firmware solution designed for ARM Cortex-M series processors, including the Cortex-M23 and Cortex-M33. These processors are often used in embedded systems requiring high levels of security and reliability. When running TF-M on Fixed Virtual Platforms (FVPs) provided by Keil, developers…

Exception Handling Timing and Instruction Interruptibility in ARMv7-M The ARMv7-M architecture, widely used in Cortex-M series processors, implements a sophisticated exception handling mechanism that is critical for real-time embedded systems. A key aspect of this mechanism is determining when exceptions are taken into account relative to the instruction flow. Exceptions in ARMv7-M can be either…