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83 lines
3.5 KiB
Markdown
83 lines
3.5 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/MCP23008/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/MCP23008/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/MCP23008/blob/master/LICENSE)
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[](https://github.com/RobTillaart/MCP23008/releases)
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# MCP23008
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Arduino library for MCP23008 8 channel I2C port expander.
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## Description
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This library gives easy control over the 8 pins of a (I2C) MCP23008 chip.
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This IC is strongly related tot the MCP23017 I2C port expander - https://github.com/RobTillaart/MCP23017_RT
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Programming Interface is kept the same as much as possible.
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Since 0.1.1 the **digitalWrite(pin, value)** is optimized.
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If a pin is not changed it will not be written again to save time.
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## Interface
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### Constructor
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- **MCP23008(uint8_t 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(uint8_t sda, uint8_t 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(uint8_t pin, uint8_t mode)** pin = 0..7, mode = INPUT, OUTPUT. Returns true if successful.
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- **bool digitalWrite(uint8_t pin, uint8_t value)** pin = 0..7, value = LOW(0) HIGH (!0). Returns true if successful.
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- **uint8_t digitalRead(uint8_t pin)** pin = 0..7, returns LOW or HIGH, might set the lastError();
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- **bool setPolarity(uint8_t pin, bool reversed)** pin = 0..7, set reversed flag. Returns true if successful.
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- **bool getPolarity(uint8_t pin, bool &reversed)** pin = 0..7, reads reversed flag. Returns true if successful.
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- **bool setPullup(uint8_t pin, bool pullup)** pin = 0..7, set pull-up flag. Returns true if successful.
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- **bool getPullup(uint8_t pin, bool &pullup)** pin = 0..7, reads pull-up flag. Returns true if successful.
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### 8 pins interface
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- **bool pinMode8(uint8_t value)** value = 0..255. Returns true if successful.
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- **bool write8(uint8_t value)** value = 0..255. Returns true if successful.
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- **uint8_t read8()** reads 8 pins into one byte.
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- **bool setPolarity8(uint8_t mask)** sets polarity for 8 channels at once. Returns true if successful.
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- **bool getPolarity8(uint8_t &mask)** reads polarity of 8 channels at once. Returns true if successful.
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- **bool setPullup8(uint8_t mask)** sets pull-up for 8 channels at once. Returns true if successful.
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- **bool getPullup8(uint8_t &mask)** reads pull-up for 8 channels at once. Returns true if successful.
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### Error codes
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If one of the above functions return false, there might be an error.
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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 **MCP23008_OK**.
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| DESCRIPTION | VALUE |
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|:-----------------------|:-------:|
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| MCP23008_OK | 0x00 |
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| MCP23008_PIN_ERROR | 0x81 |
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| MCP23008_I2C_ERROR | 0x82 |
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| MCP23008_VALUE_ERROR | 0x83 |
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| MCP23008_PORT_ERROR | 0x84 |
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## Operation
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See examples.
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## Future
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- keep in sync with MCP23017
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