Author: System on Chips

L2 Cache Stalls Due to Indefinite Memory Read Issues The ARM Cortex-A series processors are widely used in embedded systems due to their high performance and efficiency. However, certain architectural nuances can lead to unexpected behavior, particularly in the memory subsystem. One such issue is the indefinite stalling of memory reads in the L2 cache,…

Understanding ADC Channel Reading and Serial Output on ARM Cortex-M3 The process of reading an ADC channel and printing its value to a serial terminal on an ARM Cortex-M3 microcontroller, such as the ATSAM3X8E, involves several critical steps. These steps include configuring the ADC peripheral, setting up the UART for serial communication, and ensuring proper…

PL310 L2 Cache Controller RAM Initialization Overview The PL310 L2 Cache Controller, a critical component in ARM-based systems, utilizes two primary types of RAM: Data RAM and Tag RAM. These RAMs are integral to the cache’s operation, storing cached data and metadata, respectively. A common question arises regarding the initialization of these RAMs, particularly when…

ARM Cortex-R52 AXI4/128-bit Memory Interface Challenges The ARM Cortex-R52 processor, designed for real-time and safety-critical applications, features an AXI4/128-bit memory interface. This interface is crucial for achieving high bandwidth and low latency in data-intensive applications. However, integrating 128-bit memories with the Cortex-R52 can present challenges, particularly when attempting to leverage existing Intellectual Property (IP) blocks…

ARM CHI Protocol Cache Line States and the EMPTY State The ARM Coherent Hub Interface (CHI) protocol is a critical component of ARM’s advanced cache coherency framework, designed to manage data consistency across multiple cores, caches, and memory subsystems in complex System-on-Chip (SoC) designs. One of the key features of the CHI protocol is its…

ARM Trace and SPE: Distinct Use Cases and Functional Overlaps ARM Trace and the Statistical Profiling Extension (SPE) are two powerful features in ARM architectures that serve different but complementary purposes in performance analysis and debugging. ARM Trace provides a complete historical record of instruction execution, which is invaluable for debugging and code coverage tasks….

ARM Cortex-A Series Instruction Reordering and System Register Synchronization In ARM AArch64 architectures, particularly in the Cortex-A series, the processor’s out-of-order execution capabilities can lead to subtle issues when dealing with system registers and memory operations. The specific scenario involves ensuring that a write to the Performance Monitors Control Register (PMCR_EL0) is completed before a…

ARM ETM Implementation Challenges in Android Mobile Devices Embedded Trace Macrocell (ETM) is a powerful debugging and profiling tool integrated into ARM processors, enabling real-time instruction and data tracing. However, activating and utilizing ETM on ARM-based Android devices presents several challenges, particularly for developers with limited prior experience. The primary issue revolves around the lack…

ARM Cortex-M4 Assembly Preprocessor Macro Inclusion Challenges When working with ARM Cortex-M4 processors, developers often write low-level firmware in assembly language to achieve precise control over hardware resources. A common requirement is to include macros defined in C header files (.h) into assembly source files (.S) to enable conditional compilation or reuse of constants. However,…

ARM Cortex-A Permission Fault Behavior During Code Execution from Writable Memory Regions When executing code from a memory region mapped as read/write (AP[2] == 0) on an ARM Cortex-A processor, a permission fault occurs, specifically an instruction abort with exception class 0b100001 and instruction fault status code 0b001111. This fault indicates a permission fault at…