Architectures and Processors

ARM Cortex-M55 AXI 64-bit Peripheral Write Access Issue: Splitting into Two 32-bit Transactions The ARM Cortex-M55 processor, while capable of generating 64-bit AXI transactions for normal memory, splits 64-bit write accesses to peripheral (device) memory into two separate 32-bit AXI transactions. This behavior is observed when using the STRD (Store Register Dual) instruction to write…

ARM Cortex-M33 HardFault_Handler Implementation Challenges The ARM Cortex-M33 processor, part of the ARMv8-M architecture, introduces several advanced features such as TrustZone security, enhanced DSP capabilities, and improved fault handling mechanisms. However, implementing a robust HardFault_Handler for the Cortex-M33 can be challenging, especially when the goal is to capture and dump core register contents during a…

ARM Cortex-X3, A715, A510 Throughput Discrepancy in Int8 vs FP32 Multiplication The discrepancy in throughput between Int8 and FP32 multiplication on ARM Cortex-X3, A715, and A510 processors is a nuanced issue that requires a deep understanding of the underlying microarchitectures, instruction latencies, and resource availability. The expectation of a 4x increase in throughput when switching…

ARM Cortex-M7 Intrinsics and SIMD Instructions in MATLAB Simulations The core issue revolves around the challenge of emulating ARM Cortex-M7 intrinsics and SIMD (Single Instruction, Multiple Data) instructions on an x86 architecture to maintain bit-exactness in MATLAB simulations. The original algorithms were developed and qualified in MATLAB using "pure" C code, which was then encapsulated…

Understanding CDBGDCD_EL3 Register Encoding and L1 Data Cache Extraction The ARM Cortex-A55 processor provides a mechanism for direct access to internal memory, including the L1 Data (L1D) cache, through the use of debug registers. Specifically, the CDBGDCD_EL3 register is used to select a particular cache line by encoding the index, set, and way information. Once…

ARM Cortex-R Cache Architecture and Default Configuration The ARM Cortex-R series processors, such as the one used in the TI-AWR294x, are designed for real-time applications where deterministic performance is critical. These processors typically feature a hierarchical cache architecture, including Level 1 (L1) instruction and data caches, and sometimes Level 2 (L2) unified caches. The L1…

ARM Cortex-A72 SGI0 Interrupt Handling and Group Configuration Mismatch The issue at hand involves the failure of Software Generated Interrupts (SGIs) to trigger a second time on an ARM Cortex-A72 processor using the GIC-500v interrupt controller. The initial setup and triggering of SGIs (SGI0 to SGI15) work correctly, but subsequent attempts to trigger any SGI…

PendSV Exception and Interrupt Priority Mismanagement During Nested Interrupts The core issue revolves around the handling of the PendSV exception and nested interrupts in an ARM Cortex-M4-based system, specifically the S32K148 microcontroller. The problem manifests when a PendSV exception is intentionally generated during the execution of a lower-priority interrupt (Interrupt A) while interrupts are globally…

ARM Cortex-M7 SW-DP Mode and DPIDCODE Read Failure The ARM Cortex-M7 processor, a high-performance embedded processor based on the ARMv7-M architecture, supports both Serial Wire Debug (SWD) and JTAG debugging interfaces. SWD is a 2-pin interface that provides a compact and efficient alternative to JTAG for debugging and tracing. However, when attempting to read the…

Cortex-M7 System Address Map and AHBP Interface Behavior The Cortex-M7 processor, like other ARM Cortex-M series processors, utilizes a predefined memory map that divides the 32-bit address space into specific regions for different purposes. One of these regions, the System segment, spans from 0xE0100000 to 0xFFFFFFFF. This region is designated for vendor-specific devices and system…