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NOTE

Lab 7 note

Buzzer, Water Level Sensor, and Photoresistor

Lab 6 note

Wifi, AP Mode

When you set the ESP32 as an access point (hotspot), it allows you to connect to the ESP32 using any Wi-Fi-enabled device without requiring a connection to your router.

Web Server

Using Web Sever to Control ESP32

Lab 4 note

Serial Port

LCD with I2C

Lab 3 note

pwm: 模擬呼吸燈

  • Pulse Width Modulation (PWM)，脈衝寬度調製，簡稱脈寬調製。
  • PWM 信號仍然是數位的，因為在給定的任何時刻，直流供電要麼是 3.3V（ON），要麼是 0V（OFF） 。
  • 輸出電壓 =（接通時間/脈衝時間）* 最大電壓值
  • PWM 週期要短才有效
  • 使用 ESP32 ADC pins

dht11: 溫溼度感測器

ultrasonic: HC-SR04 超聲波感測器

  • measure distance
  • 使用 HC-SR04
  • 距離測量物體不可以太近、太遠、角度太大、材質需能反彈聲波
    • 距離太近會無法沒辦法將訊號反射到接受器，
    • 距離太遠則會因為訊號衰減或受到干擾，導致超音波回傳。
  • (單程)距離 = 時間 * 0.34 / 2 =時間 / 58.2

Lab 2 note

按鍵開關

Bounce (彈跳、震盪)：

  • Pushbuttons often generate spurious open/close transitions when pressed, due to mechanical and physical issues.
  • These transitions may be read as multiple presses in a very short time fooling the program.
  • bounce

Debounce (反彈跳)

Lab 1 note

delay  的缺點

  • 在 delay() 期間，不能讀取感測器、不能做數學運算、不能處理 pin 腳信號，也就是說它會讓大部分的動作都停擺。
  • 在  delay()  期間，CPU 還是可以做某些事情，例如：序列埠的 RX pin 腳進來的資料會被紀錄下來。

Blink without Delay

https://www.arduino.cc/en/Tutorial/BuiltInExamples/BlinkWithoutDelay

Turns on and off a light emitting diode (LED) connected to a digital pin, without using the delay() function.
This means that other code can run at the same time without being interrupted by the LED code.

The code below uses the millis() function, a command that returns the number of milliseconds since the board started running its current sketch, to blink an LED.

const int ledPin = LED_BUILTIN;
int ledState = LOW;

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0;  // will store last time LED was updated
const long interval = 1000;  // interval at which to blink (milliseconds)

void setup() {
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // check to see if it's time to blink the LED; that is, if the difference
  // between the current time and last time you blinked the LED is bigger than
  // the interval at which you want to blink the LED.
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;

    if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }

    digitalWrite(ledPin, ledState);
  }
}

LAB 0 note

ESP32-S3-WROOM CAM ESP32-S3