This article refers to [Wildfire EmbedFire] "RT-Thread Kernel Implementation and Application Development - Based on STM32", which is only used as a personal study note. For more detailed content and steps, please check the original text (you can download it from the Wildfire Data Download Center)

In RT-Thread, there is a printing function rt_kprintf(), which can output various information to facilitate our debugging. If you want to use rt_kprintf(), you must remap the console to rt_kprintf(). This console can be output devices such as serial port, CAN, USB, Ethernet, etc. The most used one is serial port. The serial port is redirected to rt_kprintf().

hardware initialization

The hardware to be used here is the serial port. I directly copied the bottom-level code of the serial port of Wildfire.

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Modify the board.cfile and add the serial port initialization function

void rt_hw_board_init(void)
{
    
    
#if 0
    /* TODO: OS Tick Configuration */
    _SysTick_Config(SystemCoreClock / RT_TICK_PER_SECOND);
#endif
	
	/* 初始化 SysTick */
	SysTick_Config(SystemCoreClock / RT_TICK_PER_SECOND);

	/* 硬件 BSP 初始化统统放在这里，比如 LED，串口，LCD 等 */
	
	// LED初始化
	LED_GPIO_Config();
	
	// 串口初始化
	USART_Config();

    /* Call components board initial (use INIT_BOARD_EXPORT()) */
#ifdef RT_USING_COMPONENTS_INIT
    rt_components_board_init();
#endif

#if defined(RT_USING_USER_MAIN) && defined(RT_USING_HEAP)
    rt_system_heap_init(rt_heap_begin_get(), rt_heap_end_get());
#endif
}

Custom rt_hw_console_output()

rt_kprintf()Two ways of output are supported, one is when the device driver is used, the device will be used as the console; the other is when the device driver is not used, the system processes the output device through rt_hw_console_output()functions .rt_kprintf()

rt_hw_console_output()In board.cthe implementation, the following code refers to "RT-Thread Kernel Implementation and Application Development - Based on STM32", using library functions.

#ifdef RT_USING_CONSOLE
void rt_hw_console_output(const char *str)
{
    
    
	/* 进入临界段 */
	rt_enter_critical();
	
	/* 直到字符串结束 */
	while (*str!='\0')
	{
    
    
		/* 换行 */
		if(*str=='\n')
		{
    
    
			USART_SendData(DEBUG_USARTx, '\r');
			while(USART_GetFlagStatus(DEBUG_USARTx, USART_FLAG_TXE) == RESET);
		}
		
		USART_SendData(DEBUG_USARTx, *str++);
	  	while (USART_GetFlagStatus(DEBUG_USARTx, USART_FLAG_TXE) == RESET);
	}
 		
	/* 退出临界段 */
	rt_exit_critical();
}

The first line above indicates that if you want to use the console, you also need to enable it. Method: Modify rtconfig.hand enable the corresponding macro definition.

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write test code

Next we create threads to test rt_kprintf(), using dynamic threads (the code used in the previous article)

#include "board.h"
#include "rtthread.h"

// 定义线程控制块指针
static rt_thread_t led0_thread = RT_NULL;

/******************************************************************************
* @ 函数名  ： led0_thread_entry
* @ 功  能  ： LED0线程入口函数
* @ 参  数  ： parameter 外部传入的参数
* @ 返回值  ： 无
******************************************************************************/
static void led0_thread_entry(void *parameter)
{
    
    
	while(1)
	{
    
    
		LED0(ON);
		rt_thread_delay(500); // 500个tick（500ms）
		rt_kprintf("kprintf test, LED0_ON\r\n");
		LED0(OFF);
		rt_thread_delay(500);
		rt_kprintf("kprintf test, LED0_OFF\r\n");
	}
}

int main(void)
{
    
    
	// 硬件初始化和RTT的初始化已经在component.c中的rtthread_startup()完成

	// 创建一个动态线程
	led0_thread =                                 // 线程控制块指针
	rt_thread_create("led0",                      // 线程名字
	                led0_thread_entry,            // 线程入口函数
	                RT_NULL,                      // 入口函数参数
	                255,                          // 线程栈大小
				    5,                            // 线程优先级
					10);                          // 线程时间片
	
	// 开启线程调度
	if(led0_thread != RT_NULL)
		rt_thread_startup(led0_thread);
	else
		return -1;			
}

Simulation with Keil Debug

If there is no hardware at hand, we can use Keil's Debug function to test serial port printing,

First, modify the debugging to software simulation debugging:

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Open the serial port debugging window (at this time, the serial port can only be read but not written, and the serial port transmission has not been implemented)

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