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154 lines
5.8 KiB
Markdown
154 lines
5.8 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 (I2C) MCP23017 chip.
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This IC is strongly related tot the MCP23S17 SPI port expander - https://github.com/RobTillaart/MCP23S17
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Programming Interface is kept the same as much as possible.
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Since 0.3.1 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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#### REV D - june 2022
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The I2C IO expander MCP23017 has changed according to the new data sheet. It is now a 14/16-bit IO expander.
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The pins GPA7 and GPB7 have lost their input mode, output mode still works.
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The chips look the same and did not change names.
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This implies it not possible to read 8 bits in parallel at the exact same moment any more.
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The REV D version now need reading both A and B register to get 8 bits parallel (with a minor delay).
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Details see:
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- https://hackaday.com/2023/02/03/mcp23017-went-through-shortage-hell-lost-two-inputs/
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- https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/MCP23017-Data-Sheet-DS20001952.pdf
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Note: the library has no provisions (yet) for detecting DEV D chips or handle them in a special way.
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#### Related
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16 bit port expanders
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- https://github.com/RobTillaart/MCP23017_RT
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- https://github.com/RobTillaart/MCP23S17
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- https://github.com/RobTillaart/PCF8575
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8 bit port expanders
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- https://github.com/RobTillaart/MCP23008
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- https://github.com/RobTillaart/MCP23S08
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- https://github.com/RobTillaart/PCF8574
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## Interface
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```cpp
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#include "MCP23017.h"
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```
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### Constructor
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- **MCP23017(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..15, mode = INPUT, OUTPUT. Returns true if successful.
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- **bool digitalWrite(uint8_t pin, uint8_t value)** pin = 0..15, value = LOW(0) HIGH (!0). Returns true if successful.
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- **uint8_t digitalRead(uint8_t 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 pull-up flag. Returns true if successful.
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- **bool getPullup(uint8_t pin, bool &pullup)** pin = 0..15, reads pull-up flag. Returns true if successful.
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### 8 pins interface
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- **bool pinMode8(uint8_t port, uint8_t value)** port = 0..1, value = 0..255. Returns true if successful.
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- **bool write8(uint8_t port, uint8_t value)** port = 0..1, value = 0..255. Returns true if successful.
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- **uint8_t read8(uint8_t 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
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for 8 channels at once.
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Returns true if successful.
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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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Returns true if successful.
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- **bool setPullup8(uint8_t port, uint8_t mask)** port = 0..1, sets pull-up for 8 channels at once.
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Returns true if successful.
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- **bool getPullup8(uint8_t port, uint8_t &mask)** port = 0..1, reads pull-up for 8 channels at once.
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Returns true if successful.
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### 16 pins interface
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- **bool pinMode16(uint16_t value)** value = 0..0xFFFF. Returns true if successful.
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- **bool write16(uint16_t value)** value = 0..0xFFFF. Returns true if successful.
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- **uint16_t read16()** reads 16 pins into an uint16_t.
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- **bool setPolarity16(uint16_t mask)** sets polarity for 16 channels.
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Returns true if successful.
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- **bool getPolarity16(uint16_t &mask)** reads polarity of 16 channels.
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Returns true if successful.
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- **bool setPullup16(uint16_t mask)** sets pull-up for 16 channels.
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Returns true if successful.
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- **bool getPullup16(uint16_t &mask)** reads pull-up for 16 channels.
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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 **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 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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- investigate if REV D chips can be detected.
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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 pull-up etc
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- investigate auto address increment
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#### Wont
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