/**
 * 4x4 多點觸控矩陣座標引擎 (Wokwi 模擬器物理特性補償版)
 * 
 * 腳位配置：
 * - RX 總線：PA0
 * - RX 控制 (MUX1)：PB4, PB5, PB6, PB7
 * - TX 驅動 (MUX2)：PA6, PA7, PA8, PA9
 */

const int SCREEN_MAX_X = 1024; 
const int SCREEN_MAX_Y = 768;  

const int RX_ADC_PIN = PA0;    
const int RX_PINS[] = {PB4, PB5, PB6, PB7};
const int TX_PINS[] = {PA6, PA7, PA8, PA9};

const int MATRIX_TX = 4;
const int MATRIX_RX = 4;
int Touch_Matrix[MATRIX_TX][MATRIX_RX]; 

void setup() {
  Serial.begin(115200);
  
  for (int i = 0; i < 4; i++) {
    pinMode(RX_PINS[i], OUTPUT);
    pinMode(TX_PINS[i], OUTPUT);
    digitalWrite(RX_PINS[i], LOW);
    digitalWrite(TX_PINS[i], LOW);
  }
  
  pinMode(RX_ADC_PIN, INPUT_ANALOG);
  Serial.println("==========================================");
  Serial.println("  MRTP 2D座標引擎 (Wokwi 特性補償版) 啟動!  ");
  Serial.println("==========================================");
}

void setChannel(const int pins[], int channel) {
  for (int bit = 0; bit < 4; bit++) {
    digitalWrite(pins[bit], (channel >> bit) & 1);
  }
}

void loop() {
  // 1. 矩陣掃描
  for (int tx = 0; tx < MATRIX_TX; tx++) {
    setChannel(TX_PINS, tx); 
    delayMicroseconds(50); // 拉長建立時間
    
    for (int rx = 0; rx < MATRIX_RX; rx++) {
      setChannel(RX_PINS, rx); 
      delayMicroseconds(50);   
      
      int raw_val = analogRead(RX_ADC_PIN);
      
      // 【Wokwi 專用物理補償鎖】
      // 因為 Wokwi 旋鈕無法真正與 TX 數位訊號進行動態乘積
      // 我們利用對應關係，強制在軟體層面將不屬於該 TX 通道的干擾訊號切斷
      // 實體 pot5(TX0,RX0), pot6(TX1,RX1), pot7(TX2,RX2), pot8(TX3,RX3)
      if (tx == rx) {
        Touch_Matrix[tx][rx] = raw_val; 
      } else {
        Touch_Matrix[tx][rx] = 0; // 強制阻斷虛擬短路造成的 Y 軸鎖死
      }
    }
  }

  // 2. 座標演算與解算
  long total_weight = 0;
  long weighted_X = 0;
  long weighted_Y = 0;
  int threshold = 150; // 門檻值

  for (int tx = 0; tx < MATRIX_TX; tx++) {
    for (int rx = 0; rx < MATRIX_RX; rx++) {
      int val = Touch_Matrix[tx][rx];
      if (val > threshold) {
        total_weight += val;
        weighted_X += (long)val * rx; 
        weighted_Y += (long)val * tx; 
      }
    }
  }

  // 3. 輸出真實座標與過渡斜率
  if (total_weight > 0) {
    float ratio_x = (float)weighted_X / (total_weight * (MATRIX_RX - 1));
    float ratio_y = (float)weighted_Y / (total_weight * (MATRIX_TX - 1));

    int screen_x = (int)(ratio_x * SCREEN_MAX_X);
    int screen_y = (int)(ratio_y * SCREEN_MAX_Y);

    screen_x = constrain(screen_x, 0, SCREEN_MAX_X);
    screen_y = constrain(screen_y, 0, SCREEN_MAX_Y);

    Serial.print("【觸控座標】X: ");
    if (screen_x < 100) Serial.print(" "); 
    if (screen_x < 10)  Serial.print(" ");
    Serial.print(screen_x);
    Serial.print(" px,\tY: ");
    if (screen_y < 100) Serial.print(" ");
    if (screen_y < 10)  Serial.print(" ");
    Serial.print(screen_y);
    Serial.println(" px");
  } else {
    Serial.println("[狀態] 等待觸控中...");
  }

  delay(200); 
}