ARM Cortex-M3 Clock Frequency Instability During Function Execution The core issue revolves around the STM32F103C8T6 microcontroller, which exhibits inconsistent delay timing when the CountDigit() function is executed. Specifically, the Delay(1000) function, which is expected to produce a 1-second delay, instead produces a delay of approximately 0.7 seconds after CountDigit() is called. This behavior suggests that…
Cortex-M3 Frequency Limitations in 0.18 TSMC Process Nodes The Cortex-M3 processor, a widely used ARM core in embedded systems, is known for its balance of performance, power efficiency, and cost-effectiveness. However, determining its maximum operating frequency in a specific process node, such as TSMC’s 0.18µm technology, involves a complex interplay of factors. These factors include…
ARM Cortex-A9 to Cortex-A53 Program Execution Compatibility The transition from an ARM Cortex-A9 to an ARM Cortex-A53 processor involves several architectural considerations that can impact the execution of existing programs. The Cortex-A9, based on the ARMv7-A architecture, and the Cortex-A53, based on the ARMv8-A architecture, share some similarities but also have significant differences that must…
Cortex-R5 Divide-by-Zero Exception Handling Mechanism The Cortex-R5 processor, like many ARM cores, provides a mechanism to handle arithmetic exceptions such as divide-by-zero operations. This is controlled via the System Control Register (SCTLR), specifically the DZ (Divide-by-Zero) bit. When the DZ bit is set, the processor generates an Undefined Instruction exception upon encountering a divide-by-zero operation….
Understanding ADC Cycle Timing and Microcontroller Response When configuring an Analog-to-Digital Converter (ADC) on an ARM Cortex-M microcontroller, one of the most critical parameters to consider is the ADC cycle timing. The ADC cycle timing determines how long the ADC takes to complete a conversion, which directly impacts the performance and responsiveness of the microcontroller…
GIC-500 Stuck State After Cortex-A53 Software Reset The core issue revolves around the Generic Interrupt Controller (GIC-500) in the Armada 3720 SOC entering a stuck state after a software-initiated reset of the Cortex-A53 cores. The Cortex-M3 secure coprocessor is tasked with orchestrating the reset sequence, which includes resetting the Cortex-A53 cores, peripherals, and the GIC-500….
ARMv8-A Secure EL3 to Non-Secure EL2 Transition Exception Handling Issues Secure to Non-Secure State Transition and EL2 Entry Point Execution The core issue revolves around the transition from Secure EL3 to Non-Secure EL2 in the ARMv8-A architecture, where the system encounters an unexpected exception immediately after executing the first instruction at the EL2 entry point….
ARM Cortex-A53 PM_CCNTR Behavior During WFI and CPU Load Estimation The ARM Cortex-A53 processor, part of the ARMv8-A architecture, includes a Performance Monitoring Unit (PMU) that provides various counters to measure system performance. One such counter is the PM_CCNTR (Performance Monitor Cycle Counter), which increments at the frequency of the CPU clock. The PM_CCNTR can…
Understanding LDREX/STREX and the Challenge of Testing Failure Paths The ARM architecture provides a mechanism for atomic read-modify-write operations through the use of Load-Exclusive (LDREX) and Store-Exclusive (STREX) instructions. These instructions are fundamental for implementing synchronization primitives such as compare-and-swap (CAS), increment, decrement, and semaphore locks in multi-threaded or interrupt-driven environments. The LDREX instruction loads…
ARMv6-M MOV Instruction Limitations and High Register Access The ARMv6-M architecture, a subset of the ARMv6 architecture designed for microcontrollers, imposes certain limitations on instruction encoding and register usage to optimize for low-power and cost-sensitive applications. One such limitation is documented in the ARMv6-M Architecture Reference Manual, specifically in section "A6.7.40 MOV (register)" on page…