4.8 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.
Hardware
I2C addresses
Allowed addresses are 0x20..0x27. to be set with pin A0, A1, A2.
Interface
Check the datasheet for details
#include "TCA9555.h"
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.
-
uint8_t getAddress() returns set address, (debugging).
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
- investigate map INPUT_PULLUP on INPUT (pinMode ?)
- investigate internal pull up etc.
- investigate TCA9535 differences
- pull up resistors
- elaborate derived class
- add getType() to distinguish derived classes.
- int or uint8_t => 4 or 2 digits, define?
- or even a string (no)?
- constructor
Could
- rethink class hierarchy -5535 has less functions so should be base class?
- valid address range?
Wont (unless)
- add TCA9535 error codes
- better reuse them?