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148 lines
4.7 KiB
Markdown
148 lines
4.7 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/TCA9555/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/TCA9555/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/TCA9555/blob/master/LICENSE)
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[](https://github.com/RobTillaart/TCA9555/releases)
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# TCA9555
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Arduino library for TCA9555 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 TCA9555 chip.
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The TCA9555 supports up to 400 kHz I2C.
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#### TCA9535
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from datasheet:
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_The TCA9535 is identical to the TCA9555, except that the TCA9535 does not include the internal I/O
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pull-up resistor, which requires pull-ups and pull-downs on unused I/O pins when configured as an
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input and not driven. This reduces power consumption when the I/O is held low._
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There is a TCA9535 class which is a (convenience) wrapper around the TCA9555 class.
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This allows one to create TCA9535 objects.
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## Hardware
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#### I2C addresses
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Allowed addresses are 0x20..0x27. to be set with pin A0, A1, A2.
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## Interface
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Check the datasheet for details
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```cpp
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#include "TCA9555.h"
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```
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#### Constructor
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- **TCA9555(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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- **TCA9535(uint8_t address, TwoWire \*wire = &Wire)** idem.
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- **uint8_t getType()** returns 35 or 55 depending on type.
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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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- **uint8_t getAddress()** returns set address, (debugging).
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#### 1 pin interface
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- **bool pinMode(uint8_t pin, uint8_t mode)** idem.
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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 the value of the pin HIGH or LOW.
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- **bool setPolarity(uint8_t pin, uint8_t value)** inverts polarity of an INPUT pin.
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- **uint8_t getPolarity(uint8_t pin)** returns 1 if a pin is inverted.
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#### 8 pin interface
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port = 0..1
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mask = 0..255
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- **bool pinMode8(uint8_t port, uint8_t mask)** set the mode of eight pins in one call.
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- **bool write8(uint8_t port, uint8_t mask)** returns true if successful.
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Especially useful if one needs to trigger multiple pins at the exact same time.
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- **uint8_t read8(uint8_t port)** returns a bit pattern for pins 0..7 or pins 8..15.
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- **bool setPolarity8(uint8_t port, uint8_t mask)** inverts polarity of the 8 INPUT pins in one action.
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- **uint8_t getPolarity(uint8_t port)** returns a mask with a 1 for every INPUT pin that is inverted.
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#### 16 pin interface
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Be aware that the 16 pins interface does two calls to the 8 pins interface.
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So it is impossible to switch pins from the 2 groups of 8 at exactly the same time
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without additional hardware.
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- **bool pinMode16(uint16_t mask)** set the mode of sixteen pins in one call.
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- **bool write16(uint16_t mask)** mask = 0x0000 .. 0xFFFF, returns true if successful.
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- **uint16_t read16()** Returns a bit pattern for pins 0..15.
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- **bool setPolarity16(uint16_t mask)** inverts polarity of the 8 INPUT pins in one action.
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Returns true upon success.
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- **uint16_t getPolarity()** returns a mask of 16 bits with a 1 for every INPUT pin that is inverted.
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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 **TCA9555_OK**.
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| Description | Value |
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|:-----------------------|:-------:|
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| TCA9555_OK | 0x00 |
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| TCA9555_PIN_ERROR | 0x81 |
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| TCA9555_I2C_ERROR | 0x82 |
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| TCA9555_VALUE_ERROR | 0x83 |
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| TCA9555_PORT_ERROR | 0x84 |
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| TCA9555_INVALID_READ | -100 |
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## Operation
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See examples
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## Future
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#### Must
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- buy TCA9555 / TCA9535
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- test all functionality
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- library is written without hardware
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#### Should
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- investigate map INPUT_PULLUP on INPUT (pinMode ?)
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- investigate internal pull up etc.
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- investigate TCA9535 differences
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- pull up resistors
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- elaborate derived class
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#### Could
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- rethink class hierarchy
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- TCA9535 has less functions so should be base class?
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- valid address range?
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#### Wont (unless)
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- add TCA9535 error codes
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- better reuse them?
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