NewEncoder

Interrupt-driven rotary encoder library. Works both with encoders that produce one complete quadrature cycle every detent (such as this Bourns unit sold by Adafruit) and those that produce one complete quadrature cycle for every two detents (such as this Alps unit sold by Mouser).

The encoders' switches are debounced using a state table approach.

Two interrupt-capable pins are required for each encoder connected. Thus, only one encoder can be used with an Arduino Uno for example.

The encoders' "A" and "B" terminals should be connected to the processor's inputs and its common terminal should be grounded. The library enables the processor's internal pull-ups, so external ones are not required.

Library Description:

Class NewEncoder

This provides interfacing to the encoder, interrupt handling, and rotation counting. One instance of this class is created for each encoder.

Public NewEncoder Members Functions:

Constructor - creates and configures object

NewEncoder(uint8_t aPin, uint8_t bPin, int16_t minValue, int16_t maxValue, int16_t initalValue, uint8_t type = FULL_PULSE)

Arguments:

• uint8_t aPin - Hardware pin connected to the encoder's "A" terminal.
• uint8_t bPin - Hardware pin connected to the encoder's "B" terminal.
• int16_t minValue - Lowest count value to be returned. Further anti-clockwise rotation produces no further change in output.
• int16_t maxValue - Highest count value to be returned. Further clockwise rotation produces no further change in output.
• int16_t initalValue - Initial encoder value. Should be between minValue and maxValue
• uint8_t type Type of encoder - FULL_PULSE (default, one quadrature pulse per detent) or HALF_PULSE (one quadrature pulse for every two detents)

Constructor - only creates object

NewEncoder()

Arguments: None. The object must be configured using the configure() method before being used

Configure or Re-configure an encoder object

void configure(uint8_t aPin, uint8_t bPin, int16_t minValue, int16_t maxValue, int16_t initalValue, uint8_t type = FULL_PULSE);

Arguments: Same as Constructor Returns: Nothing

Start an encoder object

bool begin();

Arguments: None

Returns: - true if encoder object successfully started, false otherwise

Disable an encoder object

 void end();

Arguments: None

Returns: Nothing

Check if encoder object is enabled

 bool enabled();

Arguments: None

Returns: - true if encoder object is enabled, false otherwise

Get current encoder value

 int16_t getValue();

Arguments: None

Returns: current encoder value, as int16_t

Note: The library overrides operator int16_t. So, if myEncoder is an encoder object, the following two statements are equivalent:

x = myEncoder.getValue();
x = myEncoder;

Set current encoder value

 int16_t setValue(int16_t val);

Arguments:

• int16_t val - New encoder value. If required, it is constrained to be between minValue and maxValue.

Returns: Value actually set, as int16_t (may be ignored)

Note: The library overrides the assignment operator. So, if myEncoder is an encoder object, the following two statements are equivalent:

myEncoder.setValue(x);
myEncoder = x;

Get current encoder value and set to new value

int16_t getAndSet(int16_t val);

Arguments:

• int16_t val - New encoder value. If required, it is constrained to be between minValue and maxValue.

Returns: Value of encoder before being set.

Note: This function reads the current encoder value and then sets the new value in an atomic manner. No counts will be missed as an interrupt can not occur between the reading and setting. Useful for periodically reading encoder attached to spinning motor to determine rotation speed.

Check if endocer has been rotated

bool upClick();
bool downClick();

Arguments: None

Returns: One of these methods will return true if the encoder has been rotated at least one detent in the associated directon (upClick() for CW, downClick() for CCW). False otherwise.

Note: Each call clears its internal flag. So, function will not return true again until another full-detent rotation has ocurred. Also, the functions will return true even if the encoder's value is saturated at the lower or upper limit.

Credits:

The direct_pin_read.h and interrupt_pins.h header files were "borrowed" directly from the PRJC Encoder Library Copyright (c) PJRC.COM, LLC - Paul Stoffregen. All typical license verbiage applies.

Other concepts were inspired by http://www.buxtronix.net/2011/10/rotary-encoders-done-properly.html