Setting Pin and Device Values

In this section, we discuss writing data to:

Digital pins.
PWM pins.
Piezo tone devices.
Servo motors.
Stepper motors.

Note: I2C devices are discussed in the next section of this guide.

digital_write

 def digital_write(self, pin, value)

    Set the specified pin to the specified value.

    :param pin: arduino pin number

    :param value: pin value (1 or 0)

Example:

digital_output.py

pwm_write

 def pwm_write(self, pin, value)

    Set the selected pwm pin to the specified value.

    :param pin: PWM pin number

    :param value: Pin value (0 - 0x4000)

Example:

pwm_analog_output.py

Notes:

The value parameter is typically set between 0 and 255.

play_tone

 def play_tone(self, pin_number, frequency, duration)

    This is FirmataExpress feature

    Play a tone at the specified frequency for the specified duration.

    :param pin_number: arduino pin number

    :param frequency: tone frequency in hz

    :param duration: duration in milliseconds

Example:

play_tone.py

play_tone_continuously

 def play_tone_continuously(self, pin_number, frequency)

    This is a FirmataExpress feature

    This method plays a tone continuously until play_tone_off is called.

    :param pin_number: arduino pin number

    :param frequency: tone frequency in hz

Example:

play_tone.py

play_tone_off

 def play_tone_off(self, pin_number)

    This is a FirmataExpress Feature

    This method turns tone off for the specified pin. 

    :param pin_number: arduino pin number

Example:

play_tone.py

servo_write

 def servo_write(self, pin, position)

    This is an alias for analog_write to set the position of a servo that has 
    been previously configured using set_pin_mode_servo.

    :param pin: arduino pin number

    :param position: servo position

Example:

servo.py

Notes:

For an angular servo, the position parameter is set between 0 and 180 (degrees). For a continuous servo, 0 is full-speed in one direction, 180 is full speed in the other, and a value near 90 is no movement.

stepper_write

 def stepper_write(self, motor_speed, number_of_steps)

    This is a FirmataExpress feature

    Move a stepper motor for the number of steps at the specified speed.

    :param motor_speed: 21 bits of data to set motor speed

    :param number_of_steps: 14 bits for number of steps & direction positive is forward, negative is reverse

Example:

stepper.py