我在MicroC中有2个任务来模拟移动的车辆：ControlTask和VehicleTask。现在我的项目应该用定时器替换上下文切换以获得更合适的时序，但我似乎无法完成它。该程序现在使用语句OSTimeDlyHMSM来实现句点，但软计时器应该与信号量一起使用。 OSTmrCreate in C / OS-II ReferenceManual（第16章）。我可以启动一个计时器，然后我可以将它放在启动代码中，但是我没有调用计时器并在用计时器替换OSTimeDlyHMSM的两个任务之间正确同步。我认为我的解决方案比必要的更复杂，因为我可能不了解所有细节，例如为什么我需要信号量以及为什么使用计时器比内置OSTimeDlyHMSM更精确。到目前为止，我的全部努力如下：
#include <stdio.h>
#include "system.h"
#include "includes.h"
#include "altera_avalon_pio_regs.h"
#include "sys/alt_irq.h"
#include "sys/alt_alarm.h"
#define DEBUG 1
#define HW_TIMER_PERIOD 100 /* 100ms */
/* Button Patterns */
#define GAS_PEDAL_FLAG 0x08
#define BRAKE_PEDAL_FLAG 0x04
#define CRUISE_CONTROL_FLAG 0x02
/* Switch Patterns */
#define TOP_GEAR_FLAG 0x00000002
#define ENGINE_FLAG 0x00000001
/* LED Patterns */
#define LED_RED_0 0x00000001 // Engine
#define LED_RED_1 0x00000002 // Top Gear
#define LED_GREEN_0 0x0001 // Cruise Control activated
#define LED_GREEN_2 0x0002 // Cruise Control Button
#define LED_GREEN_4 0x0010 // Brake Pedal
#define LED_GREEN_6 0x0040 // Gas Pedal
/*
* Definition of Tasks
*/
#define TASK_STACKSIZE 2048
OS_STK StartTask_Stack[TASK_STACKSIZE];
OS_STK ControlTask_Stack[TASK_STACKSIZE];
OS_STK VehicleTask_Stack[TASK_STACKSIZE];
// Task Priorities
#define STARTTASK_PRIO 5
#define VEHICLETASK_PRIO 10
#define CONTROLTASK_PRIO 12
// Task Periods
#define CONTROL_PERIOD 300
#define VEHICLE_PERIOD 300
/*
* Definition of Kernel Objects
*/
// Mailboxes
OS_EVENT *Mbox_Throttle;
OS_EVENT *Mbox_Velocity;
// Semaphores
OS_EVENT *aSemaphore;
// SW-Timer
OS_TMR *SWTimer;
OS_TMR *SWTimer1;
BOOLEAN status;
/*
* Types
*/
enum active {on, off};
enum active gas_pedal = off;
enum active brake_pedal = off;
enum active top_gear = off;
enum active engine = off;
enum active cruise_control = off;
/*
* Global variables
*/
int delay; // Delay of HW-timer
INT16U led_green = 0; // Green LEDs
INT32U led_red = 0; // Red LEDs
int sharedMemory=1;
void ContextSwitch()
{
printf("ContextSwitch!\n");
sharedMemory=sharedMemory*-1;
}
int buttons_pressed(void)
{
return ~IORD_ALTERA_AVALON_PIO_DATA(DE2_PIO_KEYS4_BASE);
}
int switches_pressed(void)
{
return IORD_ALTERA_AVALON_PIO_DATA(DE2_PIO_TOGGLES18_BASE);
}
/*
* ISR for HW Timer
*/
alt_u32 alarm_handler(void* context)
{
OSTmrSignal(); /* Signals a 'tick' to the SW timers */
return delay;
}
static int b2sLUT[] = {0x40, //0
0x79, //1
0x24, //2
0x30, //3
0x19, //4
0x12, //5
0x02, //6
0x78, //7
0x00, //8
0x18, //9
0x3F, //-
};
/*
* convert int to seven segment display format
*/
int int2seven(int inval){
return b2sLUT[inval];
}
/*
* output current velocity on the seven segement display
*/
void show_velocity_on_sevenseg(INT8S velocity){
int tmp = velocity;
int out;
INT8U out_high = 0;
INT8U out_low = 0;
INT8U out_sign = 0;
if(velocity < 0){
out_sign = int2seven(10);
tmp *= -1;
}else{
out_sign = int2seven(0);
}
out_high = int2seven(tmp / 10);
out_low = int2seven(tmp - (tmp/10) * 10);
out = int2seven(0) << 21 |
out_sign << 14 |
out_high << 7 |
out_low;
IOWR_ALTERA_AVALON_PIO_DATA(DE2_PIO_HEX_LOW28_BASE,out);
}
/*
* shows the target velocity on the seven segment display (HEX5, HEX4)
* when the cruise control is activated (0 otherwise)
*/
void show_target_velocity(INT8U target_vel)
{
}
/*
* indicates the position of the vehicle on the track with the four leftmost red LEDs
* LEDR17: [0m, 400m)
* LEDR16: [400m, 800m)
* LEDR15: [800m, 1200m)
* LEDR14: [1200m, 1600m)
* LEDR13: [1600m, 2000m)
* LEDR12: [2000m, 2400m]
*/
void show_position(INT16U position)
{
}
/*
* The function 'adjust_position()' adjusts the position depending on the
* acceleration and velocity.
*/
INT16U adjust_position(INT16U position, INT16S velocity,
INT8S acceleration, INT16U time_interval)
{
INT16S new_position = position + velocity * time_interval / 1000
+ acceleration / 2 * (time_interval / 1000) * (time_interval / 1000);
if (new_position > 24000) {
new_position -= 24000;
} else if (new_position < 0){
new_position += 24000;
}
show_position(new_position);
return new_position;
}
/*
* The function 'adjust_velocity()' adjusts the velocity depending on the
* acceleration.
*/
INT16S adjust_velocity(INT16S velocity, INT8S acceleration,
enum active brake_pedal, INT16U time_interval)
{
INT16S new_velocity;
INT8U brake_retardation = 200;
if (brake_pedal == off)
new_velocity = velocity + (float) (acceleration * time_interval) / 1000.0;
else {
if (brake_retardation * time_interval / 1000 > velocity)
new_velocity = 0;
else
new_velocity = velocity - brake_retardation * time_interval / 1000;
}
return new_velocity;
}
/*
* The task 'VehicleTask' updates the current velocity of the vehicle
*/
void VehicleTask(void* pdata)
{
INT8U err;
void* msg;
INT8U* throttle;
INT8S acceleration; /* Value between 40 and -20 (4.0 m/s^2 and -2.0 m/s^2) */
INT8S retardation; /* Value between 20 and -10 (2.0 m/s^2 and -1.0 m/s^2) */
INT16U position = 0; /* Value between 0 and 20000 (0.0 m and 2000.0 m) */
INT16S velocity = 0; /* Value between -200 and 700 (-20.0 m/s amd 70.0 m/s) */
INT16S wind_factor; /* Value between -10 and 20 (2.0 m/s^2 and -1.0 m/s^2) */
printf("Vehicle task created!\n");
while(1)
{
err = OSMboxPost(Mbox_Velocity, (void *) &velocity);
OSTimeDlyHMSM(0,0,0,VEHICLE_PERIOD);
/* Non-blocking read of mailbox:
- message in mailbox: update throttle
- no message: use old throttle
*/
msg = OSMboxPend(Mbox_Throttle, 1, &err);
if (err == OS_NO_ERR)
throttle = (INT8U*) msg;
/* Retardation : Factor of Terrain and Wind Resistance */
if (velocity > 0)
wind_factor = velocity * velocity / 10000 + 1;
else
wind_factor = (-1) * velocity * velocity / 10000 + 1;
if (position < 4000)
retardation = wind_factor; // even ground
else if (position < 8000)
retardation = wind_factor + 15; // traveling uphill
else if (position < 12000)
retardation = wind_factor + 25; // traveling steep uphill
else if (position < 16000)
retardation = wind_factor; // even ground
else if (position < 20000)
retardation = wind_factor - 10; //traveling downhill
else
retardation = wind_factor - 5 ; // traveling steep downhill
acceleration = *throttle / 2 - retardation;
position = adjust_position(position, velocity, acceleration, 300);
velocity = adjust_velocity(velocity, acceleration, brake_pedal, 300);
printf("Position: %dm\n", position / 10);
printf("Velocity: %4.1fm/s\n", velocity /10.0);
printf("Throttle: %dV\n", *throttle / 10);
show_velocity_on_sevenseg((INT8S) (velocity / 10));
}
}
/*
* The task 'ControlTask' is the main task of the application. It reacts
* on sensors and generates responses.
*/
void ControlTask(void* pdata)
{
INT8U err;
INT8U throttle = 40; /* Value between 0 and 80, which is interpreted as between 0.0V and 8.0V */
void* msg;
INT16S* current_velocity;
printf("Control Task created!\n");
while(1)
{
msg = OSMboxPend(Mbox_Velocity, 0, &err);
current_velocity = (INT16S*) msg;
err = OSMboxPost(Mbox_Throttle, (void *) &throttle);
OSTimeDlyHMSM(0,0,0, CONTROL_PERIOD);
}
}
/*
* The task 'StartTask' creates all other tasks kernel objects and
* deletes itself afterwards.
*/
void StartTask(void* pdata)
{
INT8U err;
void* context;
static alt_alarm alarm; /* Is needed for timer ISR function */
/* Base resolution for SW timer : HW_TIMER_PERIOD ms */
delay = alt_ticks_per_second() * HW_TIMER_PERIOD / 1000;
printf("delay in ticks %d\n", delay);
/*
* Create Hardware Timer with a period of 'delay'
*/
if (alt_alarm_start (&alarm,
delay,
alarm_handler,
context) < 0)
{
printf("No system clock available!n");
}
/*
* Create and start Software Timer
*/
SWTimer = OSTmrCreate(0,
CONTROL_PERIOD/(4*OS_TMR_CFG_TICKS_PER_SEC),
OS_TMR_OPT_PERIODIC,
ContextSwitch,
NULL,
NULL,
&err);
if (err == OS_ERR_NONE) {
/* Timer was created but NOT started */
printf("SWTimer was created but NOT started \n");
}
status = OSTmrStart(SWTimer,
&err);
if (err == OS_ERR_NONE) {
/* Timer was started */
printf("SWTimer was started!\n");
}
/*
* Creation of Kernel Objects
*/
// Mailboxes
Mbox_Throttle = OSMboxCreate((void*) 0); /* Empty Mailbox - Throttle */
Mbox_Velocity = OSMboxCreate((void*) 0); /* Empty Mailbox - Velocity */
/*
* Create statistics task
*/
OSStatInit();
/*
* Creating Tasks in the system
*/
err = OSTaskCreateExt(
ControlTask, // Pointer to task code
NULL, // Pointer to argument that is
// passed to task
&ControlTask_Stack[TASK_STACKSIZE-1], // Pointer to top
// of task stack
CONTROLTASK_PRIO,
CONTROLTASK_PRIO,
(void *)&ControlTask_Stack[0],
TASK_STACKSIZE,
(void *) 0,
OS_TASK_OPT_STK_CHK);
err = OSTaskCreateExt(
VehicleTask, // Pointer to task code
NULL, // Pointer to argument that is
// passed to task
&VehicleTask_Stack[TASK_STACKSIZE-1], // Pointer to top
// of task stack
VEHICLETASK_PRIO,
VEHICLETASK_PRIO,
(void *)&VehicleTask_Stack[0],
TASK_STACKSIZE,
(void *) 0,
OS_TASK_OPT_STK_CHK);
printf("All Tasks and Kernel Objects generated!\n");
/* Task deletes itself */
OSTaskDel(OS_PRIO_SELF);
}
/*
*
* The function 'main' creates only a single task 'StartTask' and starts
* the OS. All other tasks are started from the task 'StartTask'.
*
*/
int main(void) {
printf("Cruise Control\n");
aSemaphore = OSSemCreate(1); // binary semaphore (1 key)
OSTaskCreateExt(
StartTask, // Pointer to task code
NULL, // Pointer to argument that is
// passed to task
(void *)&StartTask_Stack[TASK_STACKSIZE-1], // Pointer to top
// of task stack
STARTTASK_PRIO,
STARTTASK_PRIO,
(void *)&StartTask_Stack[0],
TASK_STACKSIZE,
(void *) 0,
OS_TASK_OPT_STK_CHK | OS_TASK_OPT_STK_CLR);
OSStart();
return 0;
}
运行上面的程序会执行回调contextswitch，但它还没有解决使用定时器而不是内置产量以及如何将其应用于信号量的问题。
Cruise Control
delay in ticks 100
SWTimer was created but NOT started
SWTimer was started!
All Tasks and Kernel Objects generated!
Vehicle task created!
Control Task created!
ContextSwitch!
Position: 0m
Velocity: 0.5m/s
Throttle: 4V
ContextSwitch!
Position: 0m
Velocity: 1.0m/s
Throttle: 4V
Position: 0m
Velocity: 1.5m/s
Throttle: 4V
ContextSwitch!
Position: 0m
Velocity: 2.0m/s
Throttle: 4V
ContextSwitch!
Position: 1m
Velocity: 2.5m/s
Throttle: 4V
ContextSwitch!
Position: 2m
Velocity: 3.0m/s
Throttle: 4V
ContextSwitch!
2个信号量+ 2个定时器似乎是一个很好的改进。我希望可以检查或测试......
#include <stdio.h>
#include "system.h"
#include "includes.h"
#include "altera_avalon_pio_regs.h"
#include "sys/alt_irq.h"
#include "sys/alt_alarm.h"
#define DEBUG 1
#define HW_TIMER_PERIOD 100 /* 100ms */
/* Button Patterns */
#define GAS_PEDAL_FLAG 0x08
#define BRAKE_PEDAL_FLAG 0x04
#define CRUISE_CONTROL_FLAG 0x02
/* Switch Patterns */
#define TOP_GEAR_FLAG 0x00000002
#define ENGINE_FLAG 0x00000001
/* LED Patterns */
#define LED_RED_0 0x00000001 // Engine
#define LED_RED_1 0x00000002 // Top Gear
#define LED_GREEN_0 0x0001 // Cruise Control activated
#define LED_GREEN_2 0x0002 // Cruise Control Button
#define LED_GREEN_4 0x0010 // Brake Pedal
#define LED_GREEN_6 0x0040 // Gas Pedal
/*
* Definition of Tasks
*/
#define TASK_STACKSIZE 2048
OS_STK StartTask_Stack[TASK_STACKSIZE];
OS_STK ControlTask_Stack[TASK_STACKSIZE];
OS_STK VehicleTask_Stack[TASK_STACKSIZE];
// Task Priorities
#define STARTTASK_PRIO 5
#define VEHICLETASK_PRIO 10
#define CONTROLTASK_PRIO 12
// Task Periods
#define CONTROL_PERIOD 300
#define VEHICLE_PERIOD 300
/*
* Definition of Kernel Objects
*/
// Mailboxes
OS_EVENT *Mbox_Throttle;
OS_EVENT *Mbox_Velocity;
// Semaphores
OS_EVENT *aSemaphore;
OS_EVENT *aSemaphore2;
// SW-Timer
OS_TMR *SWTimer;
OS_TMR *SWTimer1;
BOOLEAN status;
/*
* Types
*/
enum active {on, off};
enum active gas_pedal = off;
enum active brake_pedal = off;
enum active top_gear = off;
enum active engine = off;
enum active cruise_control = off;
/*
* Global variables
*/
int delay; // Delay of HW-timer
INT16U led_green = 0; // Green LEDs
INT32U led_red = 0; // Red LEDs
int sharedMemory=1;
void TimerCallback(params)
{
// Post to the semaphore to signal that it's time to run the task.
OSSemPost(aSemaphore); // Releasing the key
}
void ContextSwitch()
{
printf("ContextSwitch!\n");
sharedMemory=sharedMemory*-1;
}
int buttons_pressed(void)
{
return ~IORD_ALTERA_AVALON_PIO_DATA(DE2_PIO_KEYS4_BASE);
}
int switches_pressed(void)
{
return IORD_ALTERA_AVALON_PIO_DATA(DE2_PIO_TOGGLES18_BASE);
}
/*
* ISR for HW Timer
*/
alt_u32 alarm_handler(void* context)
{
OSTmrSignal(); /* Signals a 'tick' to the SW timers */
return delay;
}
void release()
{
printf("release key!\n");
//OSSemPost(aSemaphore); // Releasing the key
OSSemPost(aSemaphore2); // Releasing the key
printf("released key!\n");
}
void release2()
{
printf("release2!\n");
OSSemPost(aSemaphore2); // Releasing the key
printf("release2!\n");
}
static int b2sLUT[] = {0x40, //0
0x79, //1
0x24, //2
0x30, //3
0x19, //4
0x12, //5
0x02, //6
0x78, //7
0x00, //8
0x18, //9
0x3F, //-
};
/*
* convert int to seven segment display format
*/
int int2seven(int inval){
return b2sLUT[inval];
}
/*
* output current velocity on the seven segement display
*/
void show_velocity_on_sevenseg(INT8S velocity){
int tmp = velocity;
int out;
INT8U out_high = 0;
INT8U out_low = 0;
INT8U out_sign = 0;
if(velocity < 0){
out_sign = int2seven(10);
tmp *= -1;
}else{
out_sign = int2seven(0);
}
out_high = int2seven(tmp / 10);
out_low = int2seven(tmp - (tmp/10) * 10);
out = int2seven(0) << 21 |
out_sign << 14 |
out_high << 7 |
out_low;
IOWR_ALTERA_AVALON_PIO_DATA(DE2_PIO_HEX_LOW28_BASE,out);
}
/*
* shows the target velocity on the seven segment display (HEX5, HEX4)
* when the cruise control is activated (0 otherwise)
*/
void show_target_velocity(INT8U target_vel)
{
}
/*
* indicates the position of the vehicle on the track with the four leftmost red LEDs
* LEDR17: [0m, 400m)
* LEDR16: [400m, 800m)
* LEDR15: [800m, 1200m)
* LEDR14: [1200m, 1600m)
* LEDR13: [1600m, 2000m)
* LEDR12: [2000m, 2400m]
*/
void show_position(INT16U position)
{
}
/*
* The function 'adjust_position()' adjusts the position depending on the
* acceleration and velocity.
*/
INT16U adjust_position(INT16U position, INT16S velocity,
INT8S acceleration, INT16U time_interval)
{
INT16S new_position = position + velocity * time_interval / 1000
+ acceleration / 2 * (time_interval / 1000) * (time_interval / 1000);
if (new_position > 24000) {
new_position -= 24000;
} else if (new_position < 0){
new_position += 24000;
}
show_position(new_position);
return new_position;
}
/*
* The function 'adjust_velocity()' adjusts the velocity depending on the
* acceleration.
*/
INT16S adjust_velocity(INT16S velocity, INT8S acceleration,
enum active brake_pedal, INT16U time_interval)
{
INT16S new_velocity;
INT8U brake_retardation = 200;
if (brake_pedal == off)
new_velocity = velocity + (float) (acceleration * time_interval) / 1000.0;
else {
if (brake_retardation * time_interval / 1000 > velocity)
new_velocity = 0;
else
new_velocity = velocity - brake_retardation * time_interval / 1000;
}
return new_velocity;
}
/*
* The task 'VehicleTask' updates the current velocity of the vehicle
*/
void VehicleTask(void* pdata)
{
INT8U err;
void* msg;
INT8U* throttle;
INT8S acceleration; /* Value between 40 and -20 (4.0 m/s^2 and -2.0 m/s^2) */
INT8S retardation; /* Value between 20 and -10 (2.0 m/s^2 and -1.0 m/s^2) */
INT16U position = 0; /* Value between 0 and 20000 (0.0 m and 2000.0 m) */
INT16S velocity = 0; /* Value between -200 and 700 (-20.0 m/s amd 70.0 m/s) */
INT16S wind_factor; /* Value between -10 and 20 (2.0 m/s^2 and -1.0 m/s^2) */
printf("Vehicle task created!\n");
// Create a semaphore to represent the "it's time to run" event.
// Initialize the semaphore count to zero because it's not time
// to run yet.
// Create a periodic software timer which calls TimerCallback()
// when it expires.
/*
* Create and start Software Timer
*/
SWTimer1 = OSTmrCreate(0,
CONTROL_PERIOD/(4*OS_TMR_CFG_TICKS_PER_SEC),
OS_TMR_OPT_PERIODIC,
TimerCallback,
NULL,
NULL,
&err);
if (err == OS_ERR_NONE) {
/* Timer was created but NOT started */
printf("SWTimer1 was created but NOT started \n");
}
status = OSTmrStart(SWTimer1,
&err);
if (err == OS_ERR_NONE) {
/* Timer was started */
printf("SWTimer1 was started!\n");
}
while(1)
{
OSSemPend(aSemaphore, 0, &err); // Trying to access the key
err = OSMboxPost(Mbox_Velocity, (void *) &velocity);
//OSTimeDlyHMSM(0,0,0,VEHICLE_PERIOD);
/* Non-blocking read of mailbox:
- message in mailbox: update throttle
- no message: use old throttle
*/
msg = OSMboxPend(Mbox_Throttle, 1, &err);
if (err == OS_NO_ERR)
throttle = (INT8U*) msg;
/* Retardation : Factor of Terrain and Wind Resistance */
if (velocity > 0)
wind_factor = velocity * velocity / 10000 + 1;
else
wind_factor = (-1) * velocity * velocity / 10000 + 1;
if (position < 4000)
retardation = wind_factor; // even ground
else if (position < 8000)
retardation = wind_factor + 15; // traveling uphill
else if (position < 12000)
retardation = wind_factor + 25; // traveling steep uphill
else if (position < 16000)
retardation = wind_factor; // even ground
else if (position < 20000)
retardation = wind_factor - 10; //traveling downhill
else
retardation = wind_factor - 5 ; // traveling steep downhill
acceleration = *throttle / 2 - retardation;
position = adjust_position(position, velocity, acceleration, 300);
velocity = adjust_velocity(velocity, acceleration, brake_pedal, 300);
printf("Position: %dm\n", position / 10);
printf("Velocity: %4.1fm/s\n", velocity /10.0);
printf("Throttle: %dV\n", *throttle / 10);
show_velocity_on_sevenseg((INT8S) (velocity / 10));
//OSSemPost(aSemaphore); // Releasing the key
}
}
/*
* The task 'ControlTask' is the main task of the application. It reacts
* on sensors and generates responses.
*/
void ControlTask(void* pdata)
{
INT8U err;
INT8U throttle = 40; /* Value between 0 and 80, which is interpreted as between 0.0V and 8.0V */
void* msg;
INT16S* current_velocity;
printf("Control Task created!\n");
while(1)
{
OSSemPend(aSemaphore2, 0, &err); // Trying to access the key
msg = OSMboxPend(Mbox_Velocity, 0, &err);
current_velocity = (INT16S*) msg;
printf("Control Task!\n");
err = OSMboxPost(Mbox_Throttle, (void *) &throttle);
//OSSemPost(aSemaphore2); // Releasing the key
//OSTimeDlyHMSM(0,0,0, CONTROL_PERIOD);
}
}
/*
* The task 'StartTask' creates all other tasks kernel objects and
* deletes itself afterwards.
*/
void StartTask(void* pdata)
{
INT8U err;
void* context;
static alt_alarm alarm; /* Is needed for timer ISR function */
/* Base resolution for SW timer : HW_TIMER_PERIOD ms */
delay = alt_ticks_per_second() * HW_TIMER_PERIOD / 1000;
printf("delay in ticks %d\n", delay);
/*
* Create Hardware Timer with a period of 'delay'
*/
if (alt_alarm_start (&alarm,
delay,
alarm_handler,
context) < 0)
{
printf("No system clock available!n");
}
/*
* Create and start Software Timer
*/
SWTimer = OSTmrCreate(0,
CONTROL_PERIOD/(4*OS_TMR_CFG_TICKS_PER_SEC),
OS_TMR_OPT_PERIODIC,
release,
NULL,
NULL,
&err);
if (err == OS_ERR_NONE) {
/* Timer was created but NOT started */
printf("SWTimer was created but NOT started \n");
}
status = OSTmrStart(SWTimer,
&err);
if (err == OS_ERR_NONE) {
/* Timer was started */
printf("SWTimer was started!\n");
}
/*
* Creation of Kernel Objects
*/
// Mailboxes
Mbox_Throttle = OSMboxCreate((void*) 0); /* Empty Mailbox - Throttle */
Mbox_Velocity = OSMboxCreate((void*) 0); /* Empty Mailbox - Velocity */
/*
* Create statistics task
*/
OSStatInit();
/*
* Creating Tasks in the system
*/
err = OSTaskCreateExt(
ControlTask, // Pointer to task code
NULL, // Pointer to argument that is
// passed to task
&ControlTask_Stack[TASK_STACKSIZE-1], // Pointer to top
// of task stack
CONTROLTASK_PRIO,
CONTROLTASK_PRIO,
(void *)&ControlTask_Stack[0],
TASK_STACKSIZE,
(void *) 0,
OS_TASK_OPT_STK_CHK);
err = OSTaskCreateExt(
VehicleTask, // Pointer to task code
NULL, // Pointer to argument that is
// passed to task
&VehicleTask_Stack[TASK_STACKSIZE-1], // Pointer to top
// of task stack
VEHICLETASK_PRIO,
VEHICLETASK_PRIO,
(void *)&VehicleTask_Stack[0],
TASK_STACKSIZE,
(void *) 0,
OS_TASK_OPT_STK_CHK);
printf("All Tasks and Kernel Objects generated!\n");
/* Task deletes itself */
OSTaskDel(OS_PRIO_SELF);
}
/*
*
* The function 'main' creates only a single task 'StartTask' and starts
* the OS. All other tasks are started from the task 'StartTask'.
*
*/
int main(void) {
printf("Cruise Control 2014\n");
aSemaphore = OSSemCreate(1); // binary semaphore (1 key)
aSemaphore2 = OSSemCreate(0); // binary semaphore (1 key)
OSTaskCreateExt(
StartTask, // Pointer to task code
NULL, // Pointer to argument that is
// passed to task
(void *)&StartTask_Stack[TASK_STACKSIZE-1], // Pointer to top
// of task stack
STARTTASK_PRIO,
STARTTASK_PRIO,
(void *)&StartTask_Stack[0],
TASK_STACKSIZE,
(void *) 0,
OS_TASK_OPT_STK_CHK | OS_TASK_OPT_STK_CLR);
OSStart();
return 0;
}
输出：
Cruise Control 2014
delay in ticks 100
SWTimer was created but NOT started
SWTimer was started!
All Tasks and Kernel Objects generated!
Vehicle task created!
SWTimer1 was created but NOT started
SWTimer1 was started!
Control Task created!
Position: 0m
Velocity: 0.4m/s
Throttle: 3V
release key!
released key!
Control Task!
Position: 0m
Velocity: 0.9m/s
Throttle: 4V
release key!
released key!
Control Task!
Position: 0m
Velocity: 1.4m/s
答案 0 :(得分：1)
OSTimeDlyHMSM()此调用允许您在HOURS中指定延迟时间，
MINUTES，SECONDS和MILLISECONDS而不是刻度。这意味着在适当的时间结束之前，您不会让任务工作。即使所有其他任务都工作和/或CPU“免费”，你的任务也不会继续工作，直到正确的时间滴答，在你的情况下，秒或其他什么都没有。如果你真的需要在如此“大”的时间之后发生一件事，那么当然还是值得使用它。
然而，定时器使用的方法不应该与信号量混淆。后者用于防止数据冲突，并保护共享资源或代码的关键部分免受多次重入。
如果不深入挖掘您的代码，我建议尽可能使用OSTimeDly()来组织您的系统。对于信号量，当您遇到多个任务可以异步调用相同的函数或访问相同的资源（如内存，寄存器，数据总线或任何硬件）时，请使用它们。
答案 1 :(得分：1)
我的印象是，您希望定期运行两个任务。并且您希望通过软件计时器和信号量来实现此目的。如果这是正确的，那么您可以按如下方式完成此操作。
每个任务都将使用它自己的信号量和计时器。信号量可以用作发生事件的信号。在这种情况下，使用信号量指示计时器已过期并且是时间运行任务。设置软件定时器以定期过期并调用回调函数。回调函数应该发布到信号量。任务应该在while循环中依赖于信号量。这样，每次计时器到期时，任务都会循环一次循环。
这是一些伪代码：
void TimerCallback(params)
{
// Post to the semaphore to signal that it's time to run the task.
}
void TaskFunction(void)
{
// Create a semaphore to represent the "it's time to run" event.
// Initialize the semaphore count to zero because it's not time
// to run yet.
// Create a periodic software timer which calls TimerCallback()
// when it expires.
while(1)
{
// Wait until it's time to run by pending on the semaphore.
// Do task specific stuff.
}
}
此软件定时器和信号量实现的周期性特性比使用OSTimeDlyHMSM（）更精确。原因是软件计时器周期独立于任务的执行时间而运行。但是OSTimeDlyHMSM（）的时间段是任务执行时间的补充。如果任务被其他任务或中断抢占，则任务的执行时间可能会因迭代而异。因此，使用OSTimeDlyHMSM（）不是获取周期性事件的非常精确的方法。
答案 2 :(得分：1)
对于定期进程，OSTimeDlyHMSM()和OSTimeDly()的问题在于它们没有考虑线程其余部分的处理时间。例如：
// Task loop
for(;;)
{
OSTimeDly( 100 ) ;
doStuffHere() ;
}
你希望doStuffHere()每100个刻度运行一次，它将除非 doStuffHere()本身需要更长的1个滴答期。例如，它可能包含延迟，或阻止其他事件。
// Task loop
for(;;)
{
OSTimeDly( 100 ) ;
doStuffHere() ;
}
通过使用计时器，可以克服这个问题：
// Note this is illustrative and not uC/OS-II code
timer_handle = createTimer( 100, PERIODIC ) ;
// Task loop
for(;;)
{
waitForTimer( timer_handle ) ;
doStuffHere() ;
}
在这里，doStuffHere()只需要少于100个滴答，使循环完全是周期性的 - 远远好于一个滴答。
所有这一切都说明如果你能保证 doStuffHere()只需要少于一个滴答 - 即使被更高优先级的任务抢占，那么延迟也会更加简单。