RTX操作系统教程[02]_rtx教程

一、信号

RTX支持每个线程多达16个信号标志。这些信号存储在线程控制块中。可以暂停一个线程的执行，直到系统中另一个线程设置了特定的信号标志或一组信号标志。

osEvent osSignalWait ( int32_t signals,uint32_t millisec);

值为0xFFFF时，定义一个无限超时时间。

如果在调用osSignalWait时将signals变量设置为零，那么设置任何标志都会导致线程继续执行。你可以通过读取oseven .value.signals的返回值来查看设置了哪个标志。

任何线程都可以在任何其他线程上设置或清除信号。

int32_t osSignalSet ( osThreadId thread_id, int32_t signals);
int32_t osSignalClear ( osThreadId thread_id, int32_t signals);

线程同步例程main：

/*----------------------------------------------------------------------------
	
	Designers Guide to the Cortex-M Family
	CMSIS RTOS Signal Example
 
*----------------------------------------------------------------------------*/
#include "stm32f10x.h"
#include <cmsis_os.h>
#include "Board_LED.h"
 
void led_Thread1 (void const *argument);
void led_Thread2 (void const *argument);
 
osThreadDef(led_Thread1, osPriorityNormal, 1, 0);
osThreadDef(led_Thread2, osPriorityNormal, 1, 0);
 
osThreadId T_led_ID1;
osThreadId T_led_ID2;
 
void delay (void)
{
unsigned int index;
const unsigned int count = 1000000;
	for(index =0;index<count;index++)
	{
		;
	}
}
/*----------------------------------------------------------------------------
  Flash LED 1 when signaled by the led_Thread2
 *---------------------------------------------------------------------------*/
void led_Thread1 (void const *argument) 
{
	for (;;) 
	{
		osSignalWait (0x00,osWaitForever);
		LED_On(1);                          
		osSignalWait (0x00,osWaitForever);	
		LED_Off(1);
	}
}
/*----------------------------------------------------------------------------
  Flash LED two and synchronise the flashing of LED 1 by setting a signal flag
 *---------------------------------------------------------------------------*/
void led_Thread2 (void const *argument) 
{
	for (;;) 
	{
		LED_On(2);		
		osSignalSet	(T_led_ID1,0x01);
		delay();
		LED_Off(2);
		osSignalSet	(T_led_ID1,0x02);
		delay();
	}
}
 
 
 
 
/*----------------------------------------------------------------------------
  Start the threads
 *---------------------------------------------------------------------------*/
int main (void) 
{
	osKernelInitialize ();                    // initialize CMSIS-RTOS
	
	LED_Initialize();
	T_led_ID2 = osThreadCreate(osThread(led_Thread2), NULL);
	T_led_ID1 = osThreadCreate(osThread(led_Thread1), NULL);	
	
	osKernelStart ();                         // start thread execution 
}

中断

在RTOS应用程序中，最好将中断服务代码设计为RTOS中的一个线程，并为其分配一个高优先级。中断线程的第一行代码应该让它等待一个信号标志。当中断发生时，ISR简单地设置信号标志并终止。这将调度为中断服务的中断线程，然后返回等待下一个信号标志被设置。

例程：

void Thread3 (void)
{
while(1)
{
osSignalWait ( isrSignal,waitForever); // Wait for the ISR to trigger an event
….. // Handle the interrupt
} // Loop round and go back sleep
}
The actual interrupt source will contain a minimal amount of code.
void IRQ_Handler (void)
{
osSignalSet (tsk3,isrSignal); // Signal Thread 3 with an event
}

ADC中断例程：

#include "stm32f10x.h"
#include "cmsis_os.h"
 
#include "Board_LED.h"
 
void led_Thread1 (void const *argument);
void led_Thread2 (void const *argument);
void adc_Thread  (void const *argument);
void init_ADC (void);						
 
osThreadDef(led_Thread1, osPriorityNormal, 1, 0);
osThreadDef(led_Thread2, osPriorityNormal, 1, 0);
osThreadDef(adc_Thread, osPriorityAboveNormal, 1, 0);
 
osThreadId T_led_ID1;
osThreadId T_led_ID2;	
osThreadId T_adc_ID;
 
 
/*----------------------------------------------------------------------------
 ADC interrupt handler. On Conversion set ADC thread signal
 *---------------------------------------------------------------------------*/
void ADC1_2_IRQHandler (void)
{
	osSignalSet(T_adc_ID,0x01);
	ADC1->SR &= ~(1 << 1);              
}
 
void adc_Thread (void const *argument)
{
	for (;;) 
	{	
		osSignalWait(0x01,osWaitForever);	
		GPIOB->ODR = ADC1->DR;
	}	
}
 
void led_Thread1 (void const *argument) 
{
	for (;;)
	{
		osSignalWait(0x01,osWaitForever);
		LED_On(1);                          
		osSignalWait(0x01,osWaitForever);	
		LED_Off(1);
	}
}
 
void led_Thread2 (void const *argument) 
{
	for (;;) 
	{
		LED_On(2);		
		osSignalSet(T_led_ID1,0x01);
		osDelay(500);
		ADC1->CR2 |=  (1UL << 22); 				//Start ADC conversion
		LED_Off(2);
		osSignalSet(T_led_ID1,0x01);
		osDelay(500);
	}
}
 
/*----------------------------------------------------------------------------
  Initilise the ADC and create the threads
 *---------------------------------------------------------------------------*/
int main (void) {
	LED_Initialize();
	init_ADC();		
	T_led_ID1 = osThreadCreate(osThread(led_Thread1), NULL);
	T_led_ID2 = osThreadCreate(osThread(led_Thread2), NULL);
	T_adc_ID = osThreadCreate(osThread(adc_Thread), NULL);	
                  
	for (;;);
}
 
/*----------------------------------------------------------------------------
  ADC initilisation code defined as a SVC function. Must be in priviliged mode to enable the NVIC interrupt
 *---------------------------------------------------------------------------*/
void init_ADC(void){
	RCC->APB2ENR |= ( 1UL <<  2);           /* enable periperal clock for GPIOA */
	GPIOA->CRL &= ~0x000000F0;              /* set PIN1 as analog input         */
 
 
  /* Setup and initialize ADC converter                                       */
	RCC->CFGR |= ( 3UL << 14);           	/* ADC clk = PCLK2 / 8              */
 
	RCC->APB2ENR |= ( 1UL <<  9);           /* enable periperal clock for ADC1  */
 
	ADC1->SQR1 = 0;                     	/* Regular chn. Sequence length = 1 */
	ADC1->SQR2 = 0;                     	/* Clear register                   */
	ADC1->SQR3 = (1UL << 0);           		/* 1. conversion = channel 1        */
	ADC1->SMPR2 = (5UL << 3);           	/* sample time channel 1  55,5 cyc. */
	ADC1->CR1 = (1UL << 8);           		/* Scan mode on                     */
	ADC1->CR2 = (7UL << 17)|           		/* select SWSTART                   */
				(1UL << 20) ;          		/* enable external Trigger          */
	ADC1->CR1 |= (1UL << 5);          		/* enable for EOC Interrupt         */
	NVIC->ISER[0] = (1UL << 18);			/* To Access the NVIC we must be in priviliged mode    */
	
}

当我们添加了一个线程时，我们还需要增加并发运行线程的数量。