UART FIFO and DMA Mode Configuration in LPC17xx and Similar ARM Microcontrollers The integration of UART (Universal Asynchronous Receiver/Transmitter) with DMA (Direct Memory Access) in ARM-based microcontrollers, such as the NXP LPC17xx series, is a powerful feature that can significantly enhance data transfer efficiency. However, the interaction between UART FIFOs (First-In-First-Out buffers) and DMA modes…
ARM Cortex-A55 Cache Verification Challenges in EL1 The ARM Cortex-A55 processor, like many modern ARM cores, features a hierarchical cache architecture with separate L1 instruction and data caches, as well as a unified L2 cache. While the ARM architecture provides mechanisms to access and manage caches at higher exception levels (EL3), performing direct cache testing…
ARM Cortex-M4 Cross Trigger Matrix Configuration and Bus Fault Analysis The ARM Cortex-M4 core, when integrated into a System-on-Chip (SoC) such as the Cypress TII MCU, provides a Cross Trigger Interface (CTI) and Cross Trigger Matrix (CTM) to enable sophisticated debugging and event management capabilities. These features allow developers to route debug events, such as…
ARM Cortex-M3 Heap Allocation Behavior with realloc() When working with dynamic memory allocation on ARM Cortex-M3 microcontrollers, developers often encounter unexpected behavior when using the realloc() function. The primary issue arises when reducing the size of a previously allocated memory block using realloc(). The expectation is that the unused portion of the memory block will…
ARM A-15 Performance Register Emulation Challenges on x86 Host Emulating ARM A-15 performance registers on an x86-based system, such as an Intel i5 laptop, presents a unique set of challenges. The primary goal is to compile a C program into ARM A-15 assembly code to accurately measure performance metrics like instruction count, CPU cycles, bus…
ARM Cortex-A72 Performance Counter Access in EL0 (User Mode) The core issue revolves around accessing the ARM Cortex-A72 cycle counter (PMCCNTR_EL0) from user mode (EL0) on a Linux-based system. The user attempted to read the cycle counter using the MRS instruction in a C program but encountered an "Illegal Instruction" error. This error indicates that…
ARMv8-A 64-bit Processors and Volatile Execution Timing When working with ARMv8-A 64-bit processors, one of the most common challenges developers face is accurately measuring the execution time of programs. This issue is particularly pronounced when using high-resolution clocks, such as std::chrono in C++, which are commonly used on Intel processors. On ARMv8-A architectures, the execution…
ARM Cortex-M33 Hard Fault During VLDR Execution The issue at hand involves a HardFault triggered by the execution of the vldr d16, [r7, #200] instruction on an ARM Cortex-M33 processor, specifically the LPC55S69 (CM33_Core0) with DSP extensions. The fault occurs during the execution of a floating-point unit (FPU) instruction, suggesting potential misconfigurations or memory access…
Cortex-A9 Core Lockup and Debugger Inability to Halt Execution When working with ARM Cortex-A9 processors, particularly in a dual-core configuration such as the Cyclone V SoC, one of the most frustrating issues that can arise during debugging is the inability to stop one of the cores. This issue manifests when using debugging tools like ARM…
ARM Cortex-M4 Frame Pointer Behavior with -fno-omit-frame-pointer The issue at hand revolves around the unexpected behavior of the frame pointer (FP) when compiling code for the ARM Cortex-M4 processor using the -fno-omit-frame-pointer compiler flag. The user expects the frame pointer to be present in the call stack, similar to how it appears in the ARM…