FIXED Burst Transactions with AxLEN > 0: Addressing and WSTRB Behavior The FIXED burst type in ARM’s AXI protocol is a specialized transaction mode designed for scenarios where the address does not increment between transfers. This is particularly useful for accessing hardware components like FIFOs, where the data width is fixed, and the same memory…
Understanding Stack Context and Frame Pointer Offsets in ARM Cortex-A15 The ARM Cortex-A15 processor, part of the ARMv7-A architecture, is widely used in embedded systems and applications requiring high performance. One common challenge developers face is analyzing the stack context to debug or monitor tasks and processes. The stack context includes critical registers such as…
WVALID, WREADY, and BVALID Signal Assertion Timing Constraints The Advanced eXtensible Interface (AXI) protocol is a high-performance, high-frequency microcontroller bus interface that is widely used in ARM-based systems. One of the critical aspects of the AXI protocol is the handshake mechanism between the master and slave devices, which ensures reliable data transfer. The handshake signals,…
Cache Coherency Challenges in ARM TrustZone During Secure-Non-Secure World Switching ARM TrustZone technology provides a robust security framework by partitioning the system into Secure and Non-Secure worlds. This partitioning ensures that sensitive data and code in the Secure world are isolated from the Non-Secure world, which typically runs less trusted applications. However, one of the…
ARM Cortex-M3 Interrupt Configuration for Push Button on LPC2148 The LPC2148 microcontroller, based on the ARM7TDMI-S core, is a popular choice for embedded systems due to its robust feature set and ease of use. One common task in embedded systems is to detect and respond to external events, such as a push button press. This…
CoreSight Trace Buffer (ETB) Continuation During CPU Exceptions In ARM-based embedded systems, CoreSight is a powerful debugging and trace technology that provides visibility into the execution of software on ARM processors. One of the key components of CoreSight is the Embedded Trace Buffer (ETB), which acts as a sink for trace data generated by the…
ARM Cortex-M4 Fixed-Point Arithmetic and Rounding Mechanism The provided assembly snippet demonstrates a common pattern used in ARM Cortex-M4 processors for handling fixed-point arithmetic, specifically focusing on rounding and overflow management. The snippet is as follows: add.w r1, r4, r5 add.w r1, r1, r1, lsr #0x1f asr r1, r1, #1 This sequence of instructions is…
AXI4 Slave Response Ordering Requirements and Protocol Violations The AXI4 protocol, as defined in the ARM AMBA specification, imposes strict requirements on the ordering of responses from slaves to ensure proper functionality and predictability in multi-master, multi-slave systems. The protocol mandates that responses for transactions with the same ID must be returned in the order…
ARMv8.5-A Memory Tagging Exception Handling Failure in Use-After-Free Scenarios Memory Tagging Enabled but No Exception on Use-After-Free Access The core issue revolves around the ARMv8.5-A architecture’s memory tagging extension (MTE), which is designed to detect and prevent memory safety violations such as use-after-free errors. When MTE is enabled, each memory allocation is assigned a tag,…
AHB Protocol Timing and Signal Interaction During Burst Transfers The Advanced High-performance Bus (AHB) protocol is a critical component of ARM’s AMBA (Advanced Microcontroller Bus Architecture) family, widely used in SoC designs for high-performance data transfers. One of the key challenges in AHB-based systems is understanding the precise timing and interaction between the HREADY and…