2.4 More About IO

2.4.1 void tone(pin, frequency, duration);

• brief: generates a square wave of the particular frequency on a pin (at a 50%　duty cycle).

• param:

  • pin: analog IO pin index, must be a value between 0 and 5, corresponding to analog pin A0 ~ A5.

  • frequency: HIGH or LOW. HIGH refers to a high level pulse, entering and leaving at a high level voltage; LOW refers to a low level pulse, entering and leaving at a low level voltage.

  • duration (optional): ms to wait for the pulse to be completed.

• return: void.

2.4.2 void noTone(pin);

• brief: stop generating a generated square wave triggered by tone(). Has no effect at all if no tone has been generated..

• param:

  • pin: analog IO pin index, must be a value between 0 and 5, corresponding to analog pin A0 ~ A5.

• return: void.

2.4.3 void shiftOut(dataPin, clockPin, bitOrder, value);

• brief: shift out a byte bit by bit.

• param:

  • dataPin: digital IO pin index, must be a value between 0 and 19, but 2 ~ 13 is preferred. Normally, pin number should be 0 ~ 13. Analog pins A0 ~ A5 can also be adopted, which is according to number 14 ~ 19. dataPin is the pin each bit is output to.

  • clockPin: after the dataPin has been set to the correct value, this clockPin is to be toggle once.

  • bitOrder: either MSBFIRST or LSBFIRST, corresponding to Most Significant Bit First or, Least Significant Bit First.

  • value: the data to shift out a byte.

• return: void.

2.4.4 byte shiftIn(dataPin, clockPin, bitOrder);

• brief: read pulse length in ms.

• param:

  • dataPin: digital IO pin index, must be a value between 0 and 19, but 2 ~ 13 is preferred. Normally, pin number should be 0 ~ 13. Analog pins A0 ~ A5 can also be adopted, which is according to number 14 ~ 19. dataPin is the pin each bit is input from.

  • clockPin: before starting reading dataPin, this clockPin is to be toggle once.

  • bitOrder: either MSBFIRST or LSBFIRST, corresponding to Most Significant Bit First or, Least Significant Bit First.

• return: byte.

2.4.5 unsigned long PulseIn(pin, value, timeout);

• brief: read pulse length in ms.

• param:

  • pin: analog IO pin index, must be a value between 0 and 5, corresponding to analog pin A0 ~ A5.

  • value: HIGH or LOW. HIGH refers to a high level pulse, entering and leaving at a high level voltage; LOW refers to a low level pulse, entering and leaving at a low level voltage.

  • timeout (optional): ms to wait for the pulse to be completed.

• return: unsigned long.