Author: System on Chips

ARM Cortex-M4 Unaligned LDR Access Timing Discrepancies When performing unaligned memory accesses using the LDR instruction on an ARM Cortex-M4 processor, the expected behavior is that two memory read cycles are required to retrieve the data, regardless of whether the address is off by 1, 2, or 3 bytes from a word-aligned boundary. However, empirical…

ARM7TDMI Interrupt Latency and Serial Communication Stall at 200kHz Input Frequency The core issue revolves around the ARM7TDMI-based LPC2368 microcontroller experiencing interrupt overload when processing high-frequency input signals, leading to the stalling of the main program loop and subsequent failure of RS232 serial communication. The LPC2368 operates at a clock speed of 48MHz and utilizes…

ARM Cortex-M4 DAP Access Failures to PPB Trace Registers When working with ARM Cortex-M4 processors, particularly in debugging scenarios, accessing the Private Peripheral Bus (PPB) region through the Debug Access Port (DAP) can present significant challenges. The PPB region houses critical debug and trace components such as the Data Watchpoint and Trace (DWT), Instrumentation Trace…

ARM Cortex-M7 Program Execution Failure Post-Flash Programming The issue at hand involves an ARM Cortex-M7-based STM32F765 microcontroller where the program compiles and flashes successfully but fails to execute after power cycling or running without a debugger attached. The program runs correctly during a debugging session, indicating that the issue is not with the code logic…

Cortex-A57 MMU Initialization Crash During TLB Invalidation The issue at hand involves a Cortex-A57 core on the NVIDIA Jetson TX2 platform crashing during the initialization phase when the Memory Management Unit (MMU) is enabled. The crash occurs specifically when executing the TLBI ALLE2 instruction, which invalidates all TLB entries at Exception Level 2 (EL2). The…

ARM Exception Handling: Synchronous Exceptions and Stack Pointer Selection In ARM architectures, particularly in ARMv8 and later, exception handling is a critical aspect of system design and debugging. A synchronous exception is one that occurs as a direct result of the execution of an instruction, such as an undefined instruction, a memory access fault, or…

ARM Cortex-A Series DDR Memory Vulnerability to Rowhammer Attacks The Rowhammer vulnerability is a significant security concern in modern computing systems, particularly those utilizing DDR memory. This issue arises due to the high-density nature of modern DRAM cells, where repeated access to a specific row of memory can cause bit flips in adjacent rows. On…

ARM Cortex-M33/M55 Vector Table Relocation and INVSTATE Fault Overview The ARM Cortex-M33 and Cortex-M55 processors, based on the ARMv8-M architecture, provide advanced features such as TrustZone security, enhanced DSP capabilities, and improved performance. One of the critical aspects of these processors is the Vector Table, which holds the addresses of exception handlers and is essential…

ARM Cortex-R7 Asynchronous External Abort Exception Analysis The ARM Cortex-R7 processor is a high-performance real-time processor designed for safety-critical and deeply embedded applications. One of the critical exceptions that can occur in such systems is the Asynchronous External Abort, which is a type of SError interrupt. This exception is particularly challenging to debug because it…

ARM Cortex-A53 Cryptography Extension: Undefined Abort Exception During SHA256 Operation The ARM Cortex-A53 processor, part of the ARMv8-A architecture, is widely used in embedded systems for its balance of performance and power efficiency. One of its notable features is the optional support for cryptographic extensions, which accelerate encryption and decryption operations. However, when attempting to…