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2.3 Analog IO

2.3.1 void analogReference(type);

  • brief: set analog reference voltage to a particular value according to different type.
    • DEFAULT: 5 Volt;
    • INTERNAL: 2.56 Volt
    • EXTERNAL: get the voltage value via AREF pin. There must be a 5K ohm pull-up resistor．
  • param:
    • type: DEFAULT, INTERNAL or EXTERNAL.
  • return: void.

2.3.2 int analogRead(pin);

  • brief: read analog voltage from a particular pin, at a period about 100US.
  • param:
    • pin: analog IO pin index, must be a value between 0 and 5, corresponding to analog pin A0 ~ A5.
  • return: int, between 0 and 1023.

2.3.3 void analogWrite(pin, value);

  • brief: write voltage value to pin, by PWM.
    • Arduino PWM is typically of frequency 490HZ.
    • On an Arduino UNO, digital pins 3, 5, 6, 9, 10, 11 with a ~ sign support PWM analog output.
    • PWM output is of 8 bits, namely, a value between 0 and 255.
  • param:
    • pin: analog IO pin index, must be a value between 0 and 5, corresponding to analog pin A0 ~ A5.
    • value: HIGH or LOW, where HIGH is for high level voltage, LOW is for low level voltage.
  • return: void.
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2.2 Digital IO
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2.4 More About IO
Last modified 5yr ago