GY-63_MS5611/libraries/rotaryDecoderSwitch

rotaryDecoderSwitch

Arduino library for a PCF8574 based rotary decoder - supports 2 rotary encoders with a switch

Description

Experimental - not tested extensively

related to https://github.com/RobTillaart/rotaryDecoder interface is kept same as much as possible.

// connect up to 2 rotary encoders with a switch to 1 PCF8574.
//
//  RotaryEncoder    PCF8574      UNO         REMARKS
//  -----------------------------------------------------------
//   1 pin A          pin 0
//   1 pin B          pin 1
//   1 switch         pin 2                   (switch to gnd)
//                    pin 3                   (reserved)
//   2 pin A          pin 4
//   2 pin B          pin 5
//   2 switch         pin 6                   (switch to gnd)
//                    pin 7                   (reserved)
//
//                    SDA         A4
//                    SCL         A5
//

Note the above mapping is sort of compatible to using the rotaryDecoder class and using device 0 and 2 only,

Interface

• rotaryDecoderSwitch(const int8_t address, TwoWire *wire = Wire); constructor to set the address and optional the Wire bus.
• bool begin(uint8_t sda, uint8_t scl, uint8_t cnt = 2) ESP32 ea initializes the class. sets I2C pins. cnt is the number of rotary encoders connected. returns true if the PCF8574 is on the I2C bus.
• bool begin(uint8_t cnt = 2) UNO ea. initializes the class. cnt is the number of rotary encoders connected. returns true if the PCF8574 is on the I2C bus.
• bool isConnected() returns true if the PCF8574 is on the I2C bus.

Core functions

• void readInitialState() read the inital state of the 2 rotary encoders. typically called in setup only, or after a sleep e.g. in combination with setValue()
• bool checkChange() polling to see if one or more RE have changed, without updating the counters.
• void update() update the internal counters of the RE, and the flags if a key is pressed. The counters will add +1 or -1 depending on direction. Need to be called before getValue() or before getKeyPressed(). Note that update() must be called as soon as possible after the interrupt occurs (or as often as possible when polling).
• void updateSingle() update the internal counters of the RE. This will add +1 +2 or +3 as it assumes that the rotary encoder only goes into a single direction.

Counters & keypresses

• uint32_t getValue(uint8_r re) returns the RE counter. (re = 0 or 1).
• void setValue(uint8_r re, uint32_t val = 0) (re)set the internal counter to val, default 0
• bool isKeyPressed(uint8_t re) returns true is the switch is pressed of the RE selected (re = 0 or 1). Note one needs to call update() first!

Debugging

• int8_t getLastPosition(uint8_r re) (re = 0 or 1).
• int8_t getRaw()

Performance

As the decoder is based upon a PCF8574, a I2C device, the performance is affected by the clockspeed of the I2C bus. All four core functions have one call to _read() which is the most expensive part.

Early tests gave the following indicative times (Arduino UNO) for the update() function. Note that above 500KHz the gain becomes less while reliability of signal decreases. (500KHz is ~3x faster than 100 KHz)

I2C speed	time (us)	delta	%%
100 KHz	234
200 KHz	136	98	42%
300 KHz	100	36	26%
400 KHz	85	15	15%
500 KHz	78	7	8%
600 KHz	67	11	14%
700 KHz	63	4	6%

At @400KHz it can update 2 rotary encoders in less than 90 us. At a 50% update percentage this implies a max of about 5000 update() calls per second in theory to be tested in practice

Note that a high speed drill goes up to 30000 RPM = 500 RPS = 2000 interrupts per second, assuming 4 pulses == 360<36>. (not tested)

Operational

See examples..

TODO

• think of what to do with the two "idle lines"