USB Connection Detection Challenges on Cortex-M7 OTG Peripheral Detecting a USB connection on a Cortex-M7 microcontroller, particularly when migrating from a K20 processor, involves understanding the differences in USB OTG (On-The-Go) peripheral implementations and register mappings. The K20 processor uses the LINESTATESTABLE field in the OTGSTAT register to reliably detect USB connections. However, the Cortex-M7,…
HSE, HSI, and PLL: Clock Sources and Multipliers in ARM Microcontrollers In ARM microcontrollers, the clock system is a critical component that determines the performance and power consumption of the device. The clock system typically consists of multiple clock sources and a Phase-Locked Loop (PLL) to generate the system clock. The High-Speed External (HSE) and…
ARM Cortex Pipeline Behavior with Nonpredicted Instructions Nonpredicted instructions in ARM architectures, such as ERET (Exception Return), have unique characteristics that can significantly impact pipeline performance. The ARM Technical Reference Manual (TRM) explicitly states that certain instructions are nonpredicted, meaning they do not follow the typical speculative execution path that most instructions do. This behavior…
Cortex-A55 AARCH32 State Configuration and Exception Handling at EL1 The ARM Cortex-A55 is a highly efficient mid-range processor core designed for a wide range of applications, from mobile devices to embedded systems. One of its key features is the ability to operate in both AARCH64 (64-bit) and AARCH32 (32-bit) execution states. However, transitioning the Cortex-A55…
ARM Cortex-M BusFault and MemManage Fault Instruction Skipping When developing firmware for ARM Cortex-M processors, encountering exceptions such as BusFault or MemManage Fault is not uncommon. These exceptions often arise due to invalid memory accesses, such as those caused by LDR (Load Register) or STR (Store Register) instructions attempting to access restricted or non-existent memory…
ARM Cortex-R5 Twin CPU Configuration and Instruction Synchronization The ARM Cortex-R5 processor is designed for real-time applications, offering dual-core (twin CPU) configurations that enable high-performance, fault-tolerant systems. However, configuring and synchronizing twin CPUs in the Cortex-R5 architecture presents unique challenges, particularly when writing instructions that ensure both cores operate in harmony without conflicts. The Cortex-R5’s…
PIO0_13 Input Pin Configuration and GPIOGetPinValue Behavior The issue revolves around the NXP LPC1347 microcontroller, specifically the PIO0_13 pin, which is configured as a digital input but consistently returns a value of 0 when read using the GPIOGetPinValue function. This occurs even when the pin is externally driven to 3.3V or grounded via a push…
ARMv8-M Exception Handling and Security State Transition Constraints The ARMv8-M architecture introduces a robust security model that partitions the system into Secure and Non-secure states. This partitioning is critical for modern embedded systems, particularly in applications requiring robust security measures such as IoT devices, automotive systems, and industrial controllers. One of the key aspects of…
i.MX RT1060 Pad Configuration Fields and Their Impact on I2C Signal Integrity The i.MX RT1060 processor, based on the ARM Cortex-M7 architecture, is widely used in embedded systems for its high performance and versatility. One of the critical aspects of working with this processor is configuring the pad control registers to ensure proper signal integrity,…
ARM Cortex-R5 Function Pointer Resolution with $Sub$ and $Super$ Pragmas The issue revolves around the behavior of function pointers in the ARM Cortex-R5 architecture when using the ARM Compiler (armcc) version 5.01, specifically in the context of the $Sub$ and $Super$ pragma directives. These directives are used to override or extend functions in embedded systems,…