[英]How to read from Serial port in FreeRTOS on Arduino using Semaphores?
我正在嘗試根據從串行端口接收到的命令來控制閃爍的任務。 這個想法是從串行端口獲取 0 以使 LED 閃爍一次。
#include <Arduino_FreeRTOS.h>
#include <semphr.h>
// define tasks
void TaskReadFromSerial( void *pvParameters ); // Get commands
void TaskBlink( void *pvParameters ); // LED as actuator
//define smaphore handlers
SemaphoreHandle_t activateActuatorSem;
//define global variable
String input = "-1";
// the setup function runs once when you press reset or power the board
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect.
}
activateActuatorSem = xSemaphoreCreateBinary();
if ( activateActuatorSem != NULL ) {
xSemaphoreGive( activateActuatorSem ); // Make the Serial Port available for use, by "Giving" the Semaphore.
}
// Now set up tasks to run independently.
xTaskCreate(
TaskBlink
, (const portCHAR *) "Blink" // A name just for humans
, 128 // This stack size can be checked & adjusted by reading the Stack Highwater
, NULL
, 2 // Priority, with 1 being the highest, and 4 being the lowest.
, NULL );
xTaskCreate(
TaskReadFromSerial
, (const portCHAR *) "ReadFromSerial"
, 128 // Stack size
, NULL
, 1 // Priority
, NULL );
// Now the task scheduler, which takes over control of scheduling individual tasks, is automatically started.
}
void loop()
{
// Empty. Things are done in Tasks.
}
/*--------------------------------------------------*/
/*---------------------- Tasks ---------------------*/
/*--------------------------------------------------*/
void TaskReadFromSerial( void *pvParameters )
{
(void) pvParameters;
for (;;)
{
if(Serial.available()>0) {
input = Serial.readString();
Serial.println("read");
if (xSemaphoreTake(activateActuatorSem, portMAX_DELAY) == pdTRUE) {
Serial.println("Input:");
Serial.println(input);
Serial.println("sema");
xSemaphoreGive(activateActuatorSem);
}
}
vTaskDelay(1);
}
}
void TaskBlink(void *pvParameters) // This is a task.
{
(void) pvParameters;
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
for (;;) // A Task shall never return or exit.
{
if (xSemaphoreTake(activateActuatorSem, portMAX_DELAY) == pdTRUE) {
if (input.equals("1\n")) {
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
vTaskDelay( 250 / portTICK_PERIOD_MS ); // wait for one second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
vTaskDelay( 250 / portTICK_PERIOD_MS ); // wait for one second
}
xSemaphoreGive(activateActuatorSem);
}
}
}
加載上面的代碼,我在顯示器中看不到任何東西,或者從我的計算機發送命令。
最后,我可以修復上面的代碼。
#include <Arduino_FreeRTOS.h>
#include <semphr.h>
// define tasks
void TaskReadFromSerial( void *pvParameters ); // Get commands
void TaskBlink( void *pvParameters ); // LED as actuator
//define smaphore handlers
SemaphoreHandle_t activateActuatorSem;
// the setup function runs once when you press reset or power the board
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect.
}
activateActuatorSem = xSemaphoreCreateBinary();
if ( activateActuatorSem != NULL )
xSemaphoreGive( activateActuatorSem ); // Make the Serial Port available for use, by "Giving" the Semaphore.
// Now set up tasks to run independently.
xTaskCreate(
TaskBlink
, (const portCHAR *) "Blink" // A name just for humans
, 256 // This stack size can be checked & adjusted by reading the Stack Highwater
, NULL
, 2 // Priority, with 1 being the highest, and 4 being the lowest.
, NULL );
xTaskCreate(
TaskReadFromSerial
, (const portCHAR *) "ReadFromSerial"
, 256 // Stack size
, NULL
, 1 // Priority
, NULL );
// Now the task scheduler, which takes over control of scheduling individual tasks, is automatically started.
}
void loop()
{
// Empty. Things are done in Tasks.
}
/*--------------------------------------------------*/
/*---------------------- Tasks ---------------------*/
/*--------------------------------------------------*/
void TaskReadFromSerial( void *pvParameters )
{
(void) pvParameters;
for (;;)
{
if(Serial.available()>0){
char c = Serial.read();
if (c == '1')
xSemaphoreGive(activateActuatorSem);
}
vTaskDelay( 250 / portTICK_PERIOD_MS );
}
}
void TaskBlink(void *pvParameters) // This is a task.
{
(void) pvParameters;
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
for (;;) // A Task shall never return or exit.
{
xSemaphoreTake(activateActuatorSem, portMAX_DELAY);
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
vTaskDelay( 250 / portTICK_PERIOD_MS ); // wait for one second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
vTaskDelay( 250 / portTICK_PERIOD_MS ); // wait for one second
}
}
ReadFromSerial 任務因為字符串而被卡住。 最好使用 char 代替。
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