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93 lines
3.5 KiB
Markdown
93 lines
3.5 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/MCP23017_RT/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/MCP23017_RT/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/MCP23017_RT/blob/master/LICENSE)
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[](https://github.com/RobTillaart/MCP23017_RT/releases)
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# MCP23017_RT
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Arduino library for MCP23017 16 channel I2C port expander.
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## Description
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This library gives easy control over the 16 pins of a MCP23017 chip.
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## Interface
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### Constructor
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- **MCP23017(address, TwoWire \*wire = &Wire)** constructor, with default Wire interface.
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Can be overruled with Wire0..WireN.
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- **bool begin()** for UNO, returns true if successful.
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- **bool begin(sda, scl)** for ESP32, returns true if successful.
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- **bool isConnected()** returns true if connected, false otherwise.
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### Single pin interface
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- **bool pinMode(pin, value)** pin = 0..15, value = INPUT, OUTPUT, returns true if successful.
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- **bool digitalWrite(pin, value)** pin = 0..15, value = LOW(0) HIGH (!0), returns true if successful.
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- **uint8_t digitalRead(pin)** pin = 0..15, returns LOW or HIGH, might set the lastError();
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- **bool setPolarity(uint8_t pin, bool reversed)** pin = 0..15, set reversed flag, returns true if successful.
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- **bool getPolarity(uint8_t pin, bool &reversed)** pin = 0..15, reads reversed flag, returns true if successful.
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- **bool setPullup(uint8_t pin, bool pullup)** pin = 0..15, set pullup flag, returns true if successful.
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- **bool getPullup(uint8_t pin, bool &pullup)** pin = 0..15, reads pullup flag, returns true if successful.
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### 8 pins interface
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- **bool pinMode8(port, value)** port = 0..1, value = 0..255, returns true if successful.
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- **bool write8(port, value)** port = 0..1, value = 0..255, returns true if successful.
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- **uint8_t read8(port)** port = 0..1, reads 8 pins into one byte.
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- **bool setPolarity8(uint8_t port, uint8_t mask)** port = 0..1, sets polarity for 8 channels at once.
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- **bool getPolarity8(uint8_t port, uint8_t &mask)** port = 0..1, reads polarity of 8 channels at once.
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- **bool setPullup8(uint8_t port, uint8_t mask)** port = 0..1,, sets pullup for 8 channels at once.
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- **bool getPullup8(uint8_t port, uint8_t &mask)** port = 0..1, reads pullup for 8 channels at once.
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### Error codes
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- **int lastError()** Above functions set an error flag that can be read with this function.
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Reading it will reset the flag to **MCP23017_OK**.
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| DESCRIPTION | VALUE |
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|:----------------------|:-----:|
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| MCP23017_OK | 0x00 |
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| MCP23017_PIN_ERROR | 0x81 |
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| MCP23017_I2C_ERROR | 0x82 |
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| MCP23017_VALUE_ERROR | 0x83 |
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| MCP23017_PORT_ERROR | 0x84 |
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## Future
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#### Must
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- Improve and extend documentation
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- add pinMode16(), write16() and read16()
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- add examples
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#### Should
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- extend error codes
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- optimize code - squeeze footprint
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- optimize code - do not write if pin does not chance (~25%)
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#### Could
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- initial value (16 bit?) as begin parameter (breaking change)
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- depends on input output pullup etc?
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- investigate auto address increment?
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## Operation
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See examples
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