#include <LiquidCrystal_I2C.h>

// 定義腳位 (對應 NUCLEO-C031C6 的 Arduino 標籤)
#define PIN_STEP 7    // D7 (PA8)
#define PIN_DIR  8    // D8 (PA9)
#define PIN_BTN  A0   // 按鈕 (PA0)
#define PIN_LED1 A1   // PA1
#define PIN_LED2 A4   // PA4
#define PIN_LED3 A5   // PA5

// 初始化 LCD (地址 0x27)
LiquidCrystal_I2C lcd(0x27, 16, 2);

int mode = 0; // 0:停止, 1:低速, 2:中速, 3:高速
unsigned long lastStepMicros = 0;
unsigned long stepInterval = 0; // 兩次步進之間的微秒間隔

void setup() {
  // 設定腳位模式
  pinMode(PIN_STEP, OUTPUT);
  pinMode(PIN_DIR, OUTPUT);
  pinMode(PIN_BTN, INPUT_PULLUP); // 啟用內部上拉，沒按時是 HIGH
  pinMode(PIN_LED1, OUTPUT);
  pinMode(PIN_LED2, OUTPUT);
  pinMode(PIN_LED3, OUTPUT);

  digitalWrite(PIN_DIR, HIGH); // 設定固定轉向
  
  // 初始化 LCD
  lcd.init();
  lcd.backlight();
  updateSystem();
}

void loop() {
  // 1. 偵測按鈕 (低電位觸發)
  if (digitalRead(PIN_BTN) == LOW) {
    delay(200); // 去彈跳
    mode = (mode + 1) % 4; // 循環狀態 0 -> 1 -> 2 -> 3 -> 0
    updateSystem();
    while (digitalRead(PIN_BTN) == LOW); // 等待放開按鈕，避免連續觸發
  }

  // 2. 驅動馬達 (非阻塞式脈衝)
  if (mode > 0) {
    unsigned long currentMicros = micros();
    if (currentMicros - lastStepMicros >= stepInterval) {
      digitalWrite(PIN_STEP, HIGH);
      delayMicroseconds(20); // 脈衝寬度，確保 A4988 抓得到
      digitalWrite(PIN_STEP, LOW);
      lastStepMicros = currentMicros;
    }
  }
}

void updateSystem() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("STM32 MOTOR CTL");
  lcd.setCursor(0, 1);

  // 根據不同模式設定步進間隔與 LED
  // 數值越小，轉速越快
  switch(mode) {
    case 0:
      stepInterval = 0;
      lcd.print("STATUS: STOP");
      digitalWrite(PIN_LED1, LOW); digitalWrite(PIN_LED2, LOW); digitalWrite(PIN_LED3, LOW);
      break;
    case 1:
      stepInterval = 8000; // 低速
      lcd.print("STATUS: LOW");
      digitalWrite(PIN_LED1, HIGH); digitalWrite(PIN_LED2, LOW); digitalWrite(PIN_LED3, LOW);
      break;
    case 2:
      stepInterval = 3000; // 中速
      lcd.print("STATUS: MID");
      digitalWrite(PIN_LED1, HIGH); digitalWrite(PIN_LED2, HIGH); digitalWrite(PIN_LED3, LOW);
      break;
    case 3:
      stepInterval = 1000; // 高速
      lcd.print("STATUS: HIGH");
      digitalWrite(PIN_LED1, HIGH); digitalWrite(PIN_LED2, HIGH); digitalWrite(PIN_LED3, HIGH);
      break;
  }
}