Pros of mbed-os

• Higher-level abstraction, making it easier for developers to write portable code
• Extensive hardware support for a wide range of ARM-based microcontrollers
• Integrated development environment (Mbed Studio) for streamlined development

Cons of mbed-os

• Larger footprint and potentially higher resource usage compared to CMSIS_5
• May introduce additional overhead due to its abstraction layers
• Less fine-grained control over low-level hardware features

Code Comparison

CMSIS_5 (low-level hardware access):

#include "stm32f4xx.h"

void initGPIO() {
    RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;
    GPIOA->MODER |= GPIO_MODER_MODER5_0;
}

mbed-os (higher-level abstraction):

#include "mbed.h"

DigitalOut led(LED1);

int main() {
    while (1) {
        led = !led;
        wait(0.5);
    }
}

This comparison highlights the difference in abstraction levels between CMSIS_5 and mbed-os. CMSIS_5 provides direct hardware access, while mbed-os offers a more user-friendly API for common tasks, sacrificing some low-level control for ease of use and portability.

Pros of Zephyr

• Supports a wider range of architectures and hardware platforms
• Offers a more comprehensive RTOS with built-in networking and device drivers
• Provides a unified development environment for various embedded systems

Cons of Zephyr

• Steeper learning curve due to its extensive feature set
• Larger memory footprint compared to CMSIS_5
• May be overkill for simple microcontroller projects

Code Comparison

CMSIS_5 (ARM Cortex-M specific):

#include "cmsis_os2.h"

void Thread_Function(void *argument) {
  // Thread code here
}

int main(void) {
  osKernelInitialize();
  osThreadNew(Thread_Function, NULL, NULL);
  osKernelStart();
  for (;;) {}
}

Zephyr (Multi-architecture support):

#include <zephyr/kernel.h>

void thread_entry(void *p1, void *p2, void *p3) {
  // Thread code here
}

int main(void) {
  k_thread_create(&my_thread, stack_area, K_THREAD_STACK_SIZEOF(stack_area),
                  thread_entry, NULL, NULL, NULL,
                  MY_PRIORITY, 0, K_NO_WAIT);
  return 0;
}

Pros of FreeRTOS

• More comprehensive real-time operating system with task scheduling and management
• Wider platform support, including non-ARM architectures
• Larger community and ecosystem with extensive documentation and examples

Cons of FreeRTOS

• Higher memory footprint and overhead compared to CMSIS
• Steeper learning curve for developers new to RTOS concepts
• May be overkill for simple, resource-constrained microcontroller projects

Code Comparison

CMSIS (Device Initialization):

SystemCoreClockUpdate();
SysTick_Config(SystemCoreClock / 1000);

FreeRTOS (Task Creation):

xTaskCreate(vTaskFunction, "Task Name", STACK_SIZE, NULL, TASK_PRIORITY, NULL);
vTaskStartScheduler();

While CMSIS focuses on hardware abstraction and low-level initialization, FreeRTOS provides higher-level task management and scheduling capabilities. CMSIS is more suitable for bare-metal programming and hardware-specific optimizations, while FreeRTOS offers a complete RTOS solution for more complex, multi-tasking applications.

Pros of STM32CubeF4

• Provides comprehensive HAL (Hardware Abstraction Layer) for STM32F4 microcontrollers
• Includes middleware libraries for various peripherals and functionalities
• Offers ready-to-use project templates and examples for STM32F4 boards

Cons of STM32CubeF4

• Limited to STM32F4 series, not applicable to other ARM-based microcontrollers
• May have a steeper learning curve for beginners compared to CMSIS
• Larger codebase and potentially higher memory footprint

Code Comparison

CMSIS_5 (Core register access):

__STATIC_INLINE uint32_t __get_PRIMASK(void)
{
  uint32_t result;
  __ASM volatile ("MRS %0, primask" : "=r" (result) );
  return(result);
}

STM32CubeF4 (HAL GPIO configuration):

GPIO_InitTypeDef GPIO_InitStruct = {0};
GPIO_InitStruct.Pin = GPIO_PIN_5;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);