GY-63_MS5611/libraries/rotaryDecoder

rotaryDecoder

Arduino library for a PCF8574 based rotary decoder - supports 4 RE.

Description

Experimental - not tested yet

Interface

• rotaryDecoder(const int8_t address, TwoWire *wire = Wire);
• bool begin(uint8_t sda, uint8_t scl, uint8_t cnt = 4) 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 = 4) 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 4 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. These will add +1 or -1 depending on direction.
• 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

• uint32_t getValue(uint8_r re) returns the RE counter.
• void setValue(uint8_r re, uint32_t val = 0) (re)set the internal counter to val, default 0

Debugging

• int8_t getLastPosition(uint8_r re)

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 (with no updates it is ~8 us faster). 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	247
200 KHz	146	99	40%
300 KHz	110	36	24%
400 KHz	95	15	14%
500 KHz	84	11	12%
600 KHz	79	5	6%
700 KHz	73	6	8%

At @400KHz it can update 4 rotary encoders in ~100us. 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..