4.3 KiB
TCA9555
Arduino library for TCA9555 16 channel I2C port expander.
Description
This library gives easy control over the 16 pins of a TCA9555 chip.
The TCA9555 supports up to 400 kHz I2C.
TCA9535
from datasheet:
The TCA9535 is identical to the TCA9555, except that the TCA9535 does not include the internal I/O pull-up resistor, which requires pull-ups and pull-downs on unused I/O pins when configured as an input and not driven. This reduces power consumption when the I/O is held low.
There is a TCA9535 class which is a (convenience) wrapper around the TCA9555 class. This allows one to create TCA9535 objects.
Interface
Check the datasheet for details
Constructor
-
TCA9555(uint8_t address, TwoWire *wire = &Wire) constructor, with default Wire interface. Can be overruled with Wire0..WireN.
-
TCA9535(uint8_t address, TwoWire *wire = &Wire) idem.
-
bool begin() for UNO, returns true if successful.
-
bool begin(uint8_t sda, uint8_t scl) for ESP32, returns true if successful.
-
bool isConnected() returns true if connected, false otherwise.
1 pin interface
- bool pinMode(uint8_t pin, uint8_t mode) idem.
- bool digitalWrite(uint8_t pin, uint8_t value) pin = 0..15, value = LOW(0) HIGH (!0), returns true if successful.
- uint8_t digitalRead(uint8_t pin) pin = 0..15, returns the value of the pin HIGH or LOW.
- bool setPolarity(uint8_t pin, uint8_t value) inverts polarity of an INPUT pin.
- uint8_t getPolarity(uint8_t pin) returns 1 if a pin is inverted.
8 pin interface
port = 0..1
mask = 0..255
- bool pinMode8(uint8_t port, uint8_t mask) set the mode of eight pins in one call.
- bool write8(uint8_t port, uint8_t mask) returns true if successful. Especially useful if one needs to trigger multiple pins at the exact same time.
- uint8_t read8(uint8_t port) returns a bit pattern for pins 0..7 or pins 8..15.
- bool setPolarity8(uint8_t port, uint8_t mask) inverts polarity of the 8 INPUT pins in one action.
- uint8_t getPolarity(uint8_t port) returns a mask with a 1 for every INPUT pin that is inverted.
16 pin interface
Be aware that the 16 pins interface does two calls to the 8 pins interface. So it is impossible to switch pins from the 2 groups of 8 at exactly the same time without additional hardware.
- bool pinMode16(uint16_t mask) set the mode of sixteen pins in one call.
- bool write16(uint16_t mask) mask = 0x0000 .. 0xFFFF, returns true if successful.
- uint16_t read16() Returns a bit pattern for pins 0..15.
- bool setPolarity16(uint16_t mask) inverts polarity of the 8 INPUT pins in one action. Returns true upon success.
- uint16_t getPolarity() returns a mask of 16 bits with a 1 for every INPUT pin that is inverted.
Error codes
- int lastError() Above functions set an error flag that can be read with this function. Reading it will reset the flag to TCA9555_OK.
| DESCRIPTION | VALUE |
|---|---|
| TCA9555_OK | 0x00 |
| TCA9555_PIN_ERROR | 0x81 |
| TCA9555_I2C_ERROR | 0x82 |
| TCA9555_VALUE_ERROR | 0x83 |
| TCA9555_PORT_ERROR | 0x84 |
| TCA9555_INVALID_READ | -100 |
Operation
See examples
Future
Must
- buy TCA9555 / TCA9535
- test all functionality (initial version is written with no hardware around)
Should
- INPUT_PULLUP mappen op INPUT (pinMode ?)
- investigate internal pull up etc.
- add TCA9535 error codes
- investigate TCA9535 differences
- elaborate derived class
Could
- rethink class hierarchy