環境: wnidows 10, STM32CubeIDE 1.8.0
開發板: stm32f407g
環境設定
首先編輯 .ioc 檔案
- 將
PA0設為GPIO_Input，並且將PA0的 Label 設為btn_blue。 - 將
PD12到PD15設為GPIO_Output，Label 設為led_green、led_orange、led_red、led_blue。
接下來設置好 FreeRTOS 的執行環境，因為網路很多教學，例如這篇，所以就不贅述。
Lab 目標
- LED_Task: state 0: First, only Green LED lights up for 2 seconds, and then only Red LED lights up for 2 seconds, and then switches back to the Green LED, then Red, and so on.
- LED_Task: state 1: Only ORANGE LED is blinking (1 second ON, 1 second OFF, …).
- Button_Task: If the button is pressed, the LED-task will switch to the other state.
撰寫主程式
編輯 Core/Src/main.c，引入標頭檔：
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/* USER CODE BEGIN Includes */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
/* USER CODE END Includes */
宣告全域變數 xQueue 作為 LED_Task 與 Button_Task 傳遞訊息的佇列、宣告 struct TaskMessage 作為傳遞訊息的資料結構。
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TaskHandle_t xHandle=NULL;
QueueHandle_t xQueue;
struct TaskMessage {
int state;
};
撰寫 Button_Task，當按鈕被按下時，將當前的 state 傳遞到 xQueue 中：
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void Button_Task(void *pvParameters) {
int pushed = 0;
static struct TaskMessage mesg = {.state = 0};
for (;;) {
if (HAL_GPIO_ReadPin(btn_blue_GPIO_Port, btn_blue_Pin)) {
if (!pushed) {
mesg.state ^= 1;
xQueueSend(xQueue, &mesg, 0);
pushed = 1;
}
} else {
pushed = 0;
}
}
}
撰寫 LED_Task，嘗試從 xQueue 抓取當前的 state，並且執行 LED 閃爍的功能：
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void LED_Task(void *pvParameters) {
int msec = 0;
int state = 0;
struct TaskMessage mesg;
for (;;) {
if (xQueueReceive(xQueue, &mesg, 0) == pdPASS) {
if (mesg.state == 0) {
HAL_GPIO_WritePin(led_orange_GPIO_Port, led_orange_Pin, GPIO_PIN_RESET);
msec = 0;
} else {
HAL_GPIO_WritePin(led_red_GPIO_Port, led_red_Pin, GPIO_PIN_RESET);
HAL_GPIO_WritePin(led_green_GPIO_Port, led_green_Pin, GPIO_PIN_RESET);
}
state = mesg.state;
}
if (state == 0) { // state 0
if (msec < 2000) {
HAL_GPIO_WritePin(led_green_GPIO_Port, led_green_Pin, GPIO_PIN_SET);
HAL_GPIO_WritePin(led_red_GPIO_Port, led_red_Pin, GPIO_PIN_RESET);
} else if (msec < 4000) {
HAL_GPIO_WritePin(led_green_GPIO_Port, led_green_Pin, GPIO_PIN_RESET);
HAL_GPIO_WritePin(led_red_GPIO_Port, led_red_Pin, GPIO_PIN_SET);
} else {
msec = 0;
HAL_GPIO_WritePin(led_green_GPIO_Port, led_green_Pin, GPIO_PIN_SET);
HAL_GPIO_WritePin(led_red_GPIO_Port, led_red_Pin, GPIO_PIN_RESET);
}
} else { // state 1
if (msec < 1000) {
HAL_GPIO_WritePin(led_orange_GPIO_Port, led_orange_Pin, GPIO_PIN_SET);
} else if (msec < 2000) {
HAL_GPIO_WritePin(led_orange_GPIO_Port, led_orange_Pin, GPIO_PIN_RESET);
} else {
msec = 0;
HAL_GPIO_WritePin(led_orange_GPIO_Port, led_orange_Pin, GPIO_PIN_SET);
}
}
vTaskDelay(1);
msec++;
}
}
最後在 main() 函式創建 LED_Task 與 Button_Task 讓 FreeRTOS 排程：
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/* USER CODE BEGIN 2 */
xQueue = xQueueCreate(3, sizeof(struct TaskMessage));
xTaskCreate(LED_Task, "LED_Task", 128, NULL, 1, &xHandle);
xTaskCreate(Button_Task, "Button_Task", 128, NULL, 1, &xHandle);
vTaskStartScheduler();
/* USER CODE END 2 */
Demo
