Author: System on Chips

Cortex-M Event Register Behavior During Interrupt Handling with SEVONPEND Enabled The Cortex-M architecture provides a robust mechanism for handling interrupts and events, which is critical for real-time embedded systems. One of the key features in this context is the Event Register, which plays a pivotal role in managing low-power modes and interrupt-driven workflows. When the…

CPSR.F Bit Manipulation Constraints in Cortex-R5F The CPSR (Current Program Status Register) in ARM architectures is a critical register that holds the processor’s current state, including condition flags, interrupt disable bits, and mode bits. Among these, the CPSR.F bit is specifically responsible for disabling Fast Interrupt Requests (FIQs). In the Cortex-R5F processor, the CPSR.F bit…

Dynamic Configuration of Watchpoints and Breakpoints in ARM Cortex-R Debug Units The ARM Cortex-R series processors are designed for real-time and safety-critical applications, where debugging capabilities are crucial for ensuring system reliability. One of the key features of the Cortex-R debug unit is its ability to dynamically configure watchpoints and breakpoints during runtime. This capability…

Cortex-M7 Flash Read-While-Write Hazards During Bootloader Operations When developing a bootloader for the ARM Cortex-M7 microcontroller, one of the critical challenges is ensuring that Flash memory operations, such as writing or erasing, do not interfere with the execution of code. This is particularly important when the bootloader code is executed from RAM, but the microcontroller…

ARM Cortex-M33 Lockup State at vStartFirstTask Due to SVC Instruction The issue at hand involves an ARM Cortex-M33 processor entering a lockup state during the initialization of the FreeRTOS scheduler, specifically when executing the vStartFirstTask function. The lockup occurs at the SVC %0 instruction, which is a system call designed to start the first task…

ARM AHB-Lite Protocol and HMASTLOCK Signal Overview The ARM Advanced High-performance Bus Lite (AHB-Lite) protocol is a widely used on-chip communication standard for high-performance embedded systems. It is designed to facilitate efficient data transfer between masters (such as CPUs, DMAs, or other peripherals) and slaves (such as memory controllers, registers, or other peripherals). One of…

Cortex-R5F Advanced SIMD Support Discrepancy in ARMv7-R Architecture The Cortex-R5F processor, part of the ARMv7-R architecture profile, has been a topic of confusion regarding its support for Advanced SIMD (Single Instruction Multiple Data) instructions. The ARM Cortex-R5F Technical Reference Manual (TRM) revision r1p2 initially states that the Cortex-R5 processor implements the ARMv7-R architecture profile, which…

Event Recorder RAM Allocation Exceeds Expected Size on STM32F0 When configuring the Event Recorder on an STM32F0 microcontroller using ARM-MDK 5.27, the RAM allocation for the Event Recorder exceeds the expected size. Specifically, setting the record count to 64U, which should theoretically require 1,024 bytes (16 bytes per record), results in a linker error indicating…

ARM Stage 1 Virtual Address Translation and Concatenation Constraints In ARM architectures, virtual address (VA) translation is a critical process that enables the operating system to manage memory efficiently. The translation process is typically divided into two stages: Stage 1 and Stage 2. Stage 1 is responsible for translating virtual addresses to intermediate physical addresses…

ARM Cortex-M0/M0+/M1 32-bit x 32-bit to 64-bit Multiplication Challenges The ARM Cortex-M0, M0+, and M1 processors are widely used in embedded systems due to their low power consumption and cost-effectiveness. However, these processors lack a native 64-bit multiply instruction, which poses a significant challenge when performing 32-bit x 32-bit multiplication to produce a 64-bit result….