GY-63_MS5611/libraries/rotaryDecoder
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rotaryDecoder.h add rotaryDecoder 2021-05-17 16:29:53 +02:00

Arduino CI License: MIT GitHub release

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..