ARM Cortex-A7 Exception Vector Table: Entries as Instructions or Addresses? The ARM Cortex-A7 processor, like other ARMv7-A architecture processors, utilizes an exception vector table to handle exceptions and interrupts. The vector table contains entries that define the starting points for exception handlers. Each entry in the vector table corresponds to a specific exception type, such…
ARM AArch64 Memory-Mapped I/O Architecture and Challenges In ARM AArch64 architecture, input/output (I/O) operations are fundamentally different from traditional x86 architectures. Unlike x86, which employs a separate I/O address space and dedicated instructions like inb and outb, ARM uses a unified memory-mapped I/O approach. This means that peripherals such as UARTs, GPIOs, and timers are…
ARM Cortex-M33 Secure-Non-Secure Transition Failure with SG Instruction The ARM Cortex-M33 processor, part of the ARMv8-M architecture, introduces a robust security model that allows for the partitioning of code and data into secure and non-secure worlds. This partitioning is essential for applications requiring high levels of security, such as IoT devices, where sensitive data and…
GICv2 Interrupt Auto-Deassertion Behavior on Cortex-R5 The issue at hand involves the unexpected auto-deassertion of a timer interrupt configured on IRQ#226 in a Cortex-R5 system utilizing a Generic Interrupt Controller version 2 (GICv2). The interrupt is enabled in both the distributor and CPU interface blocks, assigned to Group#1. Upon enabling the interrupt, it immediately enters…
Cortex-A53 AMP Architecture and Shared Memory Challenges in FreeRTOS The ARM Cortex-A53 is a highly efficient processor core designed for a wide range of applications, including high-performance real-time control systems. When implementing an Asynchronous Multiprocessing (AMP) scheme on a Cortex-A53 platform, several architectural and practical challenges arise, particularly when dealing with shared memory, cache coherency,…
Cortex-M1 Softcore Processor Application Project Generation Failure in Vitis 2020.1 The core issue revolves around the failure to generate an application project in Vitis 2020.1 for a Cortex-M1 softcore processor implemented on an Arty A7 100T FPGA. The user successfully generated a bitstream for a simple AXI-Uartlite project using Vivado 2020.1 and exported the hardware…
Understanding Fixed-Point Arithmetic Precision in ARM Processors Fixed-point arithmetic is a critical topic in embedded systems, especially when dealing with processors that lack a Floating-Point Unit (FPU). The precision of fixed-point arithmetic is inherently tied to the bit-width of the processor and the specific fixed-point representation used. For a 16-bit processor, the precision is determined…
PL080 DMA Controller FIFO Functionality and Performance Impact The PrimeCell® DMA Controller (PL080) is a highly configurable Direct Memory Access (DMA) controller designed for ARM-based SoCs. It features two AHB (Advanced High-performance Bus) interfaces and eight DMA channels, each capable of handling independent data transfers. One of the key architectural features of the PL080 is…
AXI4 WSTRB Signal Interpretation and Use Case Analysis The AXI4 protocol defines the WSTRB signal as a critical component for managing valid byte lanes during write transactions. The WSTRB signal is a bitmask that indicates which byte lanes of the WDATA bus contain valid data. For a 128-bit WDATA bus, the WSTRB signal is 16…
UMC28nm Process Library Units SDFFYSQ2D_X1M_A12PP140ZTS_C35, SDFFYSQ3D_X1M_A12PP140ZTS_C35, and SDFFYSQ4D_X1M_A12PP140ZTS_C35 Marked as "Don’t Use" and "Don’t Touch" In the UMC28nm process library, specific units such as SDFFYSQ2D_X1M_A12PP140ZTS_C35, SDFFYSQ3D_X1M_A12PP140ZTS_C35, and SDFFYSQ4D_X1M_A12PP140ZTS_C35 are flagged with "don’t use" and "don’t touch" properties. These flags are critical for designers to understand, as they directly impact the usability and reliability of these…