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https://github.com/RobTillaart/Arduino.git
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111 lines
4.5 KiB
Markdown
111 lines
4.5 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/rotaryDecoderSwitch/blob/master/LICENSE)
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[](https://github.com/RobTillaart/rotaryDecoderSwitch/releases)
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# rotaryDecoderSwitch
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Arduino library for a PCF8574 based rotary decoder - supports 2 rotary encoders with a switch
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## Description
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Experimental - not tested extensively
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related to https://github.com/RobTillaart/rotaryDecoder
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interface is kept same as much as possible.
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```cpp
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// connect up to 2 rotary encoders with a switch to 1 PCF8574.
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//
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// RotaryEncoder PCF8574 UNO REMARKS
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// -----------------------------------------------------------
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// 1 pin A pin 0
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// 1 pin B pin 1
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// 1 switch pin 2 (switch to gnd)
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// pin 3 (reserved)
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// 2 pin A pin 4
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// 2 pin B pin 5
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// 2 switch pin 6 (switch to gnd)
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// pin 7 (reserved)
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//
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// SDA A4
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// SCL A5
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//
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```
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Note the above mapping is sort of compatible to using the rotaryDecoder class and using device 0 and 2 only,
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## Interface
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- **rotaryDecoderSwitch(const int8_t address, TwoWire \*wire = Wire);** constructor to set the address and optional the Wire bus.
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- **bool begin(uint8_t sda, uint8_t scl, uint8_t cnt = 2)** ESP32 ea initializes the class.
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sets I2C pins.
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cnt is the number of rotary encoders connected.
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returns true if the PCF8574 is on the I2C bus.
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- **bool begin(uint8_t cnt = 2)** UNO ea. initializes the class.
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cnt is the number of rotary encoders connected.
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returns true if the PCF8574 is on the I2C bus.
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- **bool isConnected()** returns true if the PCF8574 is on the I2C bus.
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## Core functions
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- **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()**
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- **bool checkChange()** polling to see if one or more RE have changed, without updating the counters.
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- **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).
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- **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.
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## Counters & keypresses
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- **uint32_t getValue(uint8_r re)** returns the RE counter. (re = 0 or 1).
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- **void setValue(uint8_r re, uint32_t val = 0)** (re)set the internal counter to val, default 0
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- **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!
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## Debugging
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- **int8_t getLastPosition(uint8_r re)** (re = 0 or 1).
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- **int8_t getRaw()**
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## Performance
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As the decoder is based upon a PCF8574, a I2C device, the performance is affected by the
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clockspeed of the I2C bus. All four core functions have one call to **\_read()** which is the most expensive part.
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Early tests gave the following indicative times (Arduino UNO) for the **update()**
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function. Note that above 500KHz the gain becomes less
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while reliability of signal decreases. (500KHz is ~3x faster than 100 KHz)
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| I2C speed | time (us) | delta | %% |
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|:---------:|:---------:|:-----:|:-----:|
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| 100 KHz | 234 | | |
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| 200 KHz | 136 | 98 | 42% |
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| 300 KHz | 100 | 36 | 26% |
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| 400 KHz | 85 | 15 | 15% | preferred max
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| 500 KHz | 78 | 7 | 8% |
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| 600 KHz | 67 | 11 | 14% | (strange outlier)
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| 700 KHz | 63 | 4 | 6% |
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At @400KHz it can update 2 rotary encoders in less than 90 us.
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At a 50% update percentage this implies a max of about
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5000 **update()** calls per second in theory
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**to be tested in practice**
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Note that a high speed drill goes up to 30000 RPM = 500 RPS = 2000 interrupts per second,
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assuming 4 pulses == 360<36>. (not tested)
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## Operational
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See examples..
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## TODO
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- think of what to do with the two "idle lines"
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