ARM Cortex-M UART Configuration and Data Flow Management When working with multiple UARTs on an STM32 microcontroller, the primary challenge lies in efficiently managing data reception from two UART peripherals and forwarding the received data to a PC via a third UART. This scenario requires careful configuration of the UART peripherals, proper handling of interrupts,…
Understanding Optimization Levels in Keil MDK ARM for Cortex-M0 and Cortex-M3 When working with ARM Cortex-M0 and Cortex-M3 processors in the Keil MDK ARM environment, selecting the appropriate optimization level is crucial for balancing performance, code size, and debugging ease. Optimization levels in Keil MDK ARM range from -O0 (no optimization) to -O3 (maximum optimization),…
ARM Cortex-M7 Privilege Level Determination in Thread and Handler Modes The ARM Cortex-M7 processor, like other Cortex-M series processors, operates in two primary modes: Thread mode and Handler mode. Thread mode is used for executing application code, while Handler mode is entered when an exception or interrupt occurs. Each mode can operate at different privilege…
RTX5 Thread Creation Failure and LED Blinking Issue on STM32F103RB The core issue revolves around the failure of an STM32F103RB microcontroller to blink an LED connected to GPIO pin A_5 when using the CMSIS-RTOS2 API with RTX5 as the underlying Real-Time Operating System (RTOS). The code compiles without errors or warnings, and the same implementation…
Undefined References to System Calls in ARM Cortex-M0+ Cross-Compilation When attempting to cross-compile a simple "hello world" program for an ARM Cortex-M0+ target using the GCC ARM embedded toolchain, the linker fails with multiple undefined references to system calls such as _exit, _sbrk, _write, _close, _lseek, _read, _fstat, and _isatty. These errors indicate that the…
ARM Cortex-M4 VCVT Floating-Point to Fixed-Point Conversion Syntax Issue The ARM Cortex-M4 processor, equipped with a Floating-Point Unit (FPU), provides robust support for floating-point operations, including the conversion between floating-point and fixed-point representations. The VCVT instruction is a critical component of this functionality, enabling developers to perform these conversions efficiently. However, a specific issue arises…
Using __get_IPSR() to Identify Interrupt Sources in a Shared ISR The Cortex-M0+ microcontroller, like other ARM Cortex-M processors, supports a flexible interrupt handling mechanism that allows developers to use a single Interrupt Service Routine (ISR) for multiple interrupt sources. This approach is particularly useful when implementing an "OS-like" function that centralizes interrupt handling, performs privilege…
ARM Cortex-A73 and Cortex-A53 Performance Discrepancy in ResNet50 Inference When running neural network inference tasks on a HiKey970 board equipped with ARM Cortex-A73 (big) and Cortex-A53 (LITTLE) cores, an unexpected performance discrepancy was observed. Specifically, the inference time for ResNet50 was nearly double when running on the big cores compared to the LITTLE cores. This…
ARM Cortex-M Dual Stack Pointer Architecture and Context Switching Challenges The ARM Cortex-M architecture employs a dual stack pointer mechanism, utilizing both the Main Stack Pointer (MSP) and the Process Stack Pointer (PSP). This design is pivotal for separating kernel and user tasks, enhancing system reliability and security. The MSP is typically used for exception…
SWD Protocol Initialization and IDCODE Read Success but MEM-AP Access Failure The core issue revolves around the successful initialization of the Serial Wire Debug (SWD) protocol and the ability to read the IDCODE register on an ARM Cortex-M0 processor, but subsequent failure to access the Memory Access Port (MEM-AP). The IDCODE register read operation returns…