*I2C相關知識¶

韌體開發前請先研讀I2C相關知識包含：需要幾條線、電路、接線、時序圖、START Condition、Stop Condition...
參考資料 or 自行Google：
https://wiki.csie.ncku.edu.tw/embedded/I2C
https://rexpighj123.pixnet.net/blog/post/219960237¶

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*TCA6507¶

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以下程式應用 Wire.h 完成 Datasheet 上要求的規則，達到傳輸資料的效果¶

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*程式¶

#include <Wire.h>

//ESP32 I2C 腳位 & TCA6507 Enable
#define SDA 21
#define SCL 22
#define EN 26

enum TCA_registers{
  SELECT0 = 0x00,
  SELECT1 = 0x01,
  SELECT2 = 0x02,
  FADE_ON_TIME = 0x03,
  FULLY_ON_TIME = 0x04,
  FADE_OFF_TIME = 0x05,
  FIRST_FULLY_OFF_TIME = 0x06,
  SECOND_FULLY_OFF_TIME = 0x06,
  MAXIMUM_INTENSITY = 0x08,
  ONE_SHOT = 0x09,
  INITIALIZATION = 0x10,
};

int8_t TCA_writeBytes(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint8_t *data){
  uint8_t status = 0;

  Wire.beginTransmission(devAddr);
  Wire.write(regAddr);

  for (uint8_t i = 0; i < length; i++) {
    Wire.write((uint8_t) data[i]);
  }

  status = Wire.endTransmission();
  return status == 0;
}

int8_t TCA_writeByte(uint8_t devAddr, uint8_t regAddr, uint8_t data){
  return TCA_writeBytes(devAddr, regAddr, 1, &data);
}

int8_t TCA_read(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint8_t *data, uint16_t timeout){

  int8_t count = 0;
  uint32_t t1 = millis();

  for (uint8_t k = 0; k < length; k += std::min<int>(length, BUFFER_LENGTH)) {
    Wire.beginTransmission(devAddr);
    Wire.write(regAddr);
    Wire.endTransmission();

    Wire.requestFrom(devAddr, (uint8_t) std::min<int> (length - k, BUFFER_LENGTH));

    for (; Wire.available() && (timeout == 0 || millis() - t1 < timeout); count++) {
        data[count] = Wire.read();
    }
  }

  if (timeout > 0 && millis() - t1 >= timeout && count < length) count = -1; // timeout

  return count;
}

bool TCA_isConnected(){
  uint8_t result = 0;

  return ( TCA_read(device_address, SELECT0, 1, &result, 0) == 1);
}

void setup() {
  Serial.begin(115200);

  Wire.begin(SDA, SCL);

  pinMode(EN, OUTPUT);
  digitalWrite(EN, LOW);
  delay(20);
  digitalWrite(EN, HIGH);
  delay(20);

  if(TCA_isConnected()){
    Serial.print("TCA6507 connected!!");
  }
  else{
    Serial.print("TCA6507 doesn't connected.");
  }
}

void loop() {
  //on_off在後續LCD螢幕上可以用觸控來控制
  //先試試用Serial port控制 或 讓on_off每隔1秒+1 讓燈閃爍
  if(on_off % 2 == 1){
    uint8_t selects[3] = {0x00, 0x00, 0x1E};
    TCA_writeByte(device_address, SELECT2, selects[2]);
  }

  if(on_off % 2 == 0){
    TCA_writeByte(device_address, SELECT2, 0x00);
  }
}