GY-63_MS5611/libraries/MCP23017_RT/README.md

MCP23017_RT

Arduino library for MCP23017 16 channel I2C port expander.

Description

This library gives easy control over the 16 pins of a (I2C) MCP23017 chip.

This IC is strongly related tot the MCP23S17 SPI port expander - https://github.com/RobTillaart/MCP23S17 Programming Interface is kept the same as much as possible.

Interface

Constructor

• MCP23017(uint8_t address, TwoWire *wire = &Wire) constructor, with default Wire interface.
  Can be overruled with Wire0..WireN.
• 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.

Single pin interface

• bool pinMode(uint8_t pin, uint8_t mode) pin = 0..15, mode = INPUT, OUTPUT, returns true if successful.
• 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 LOW or HIGH, might set the lastError();
• bool setPolarity(uint8_t pin, bool reversed) pin = 0..15, set reversed flag, returns true if successful.
• bool getPolarity(uint8_t pin, bool &reversed) pin = 0..15, reads reversed flag, returns true if successful.
• bool setPullup(uint8_t pin, bool pullup) pin = 0..15, set pull-up flag, returns true if successful.
• bool getPullup(uint8_t pin, bool &pullup) pin = 0..15, reads pull-up flag, returns true if successful.

8 pins interface

• bool pinMode8(uint8_t port, uint8_t value) port = 0..1, value = 0..255, returns true if successful.
• bool write8(uint8_t port, uint8_t value) port = 0..1, value = 0..255, returns true if successful.
• uint8_t read8(uint8_t port) port = 0..1, reads 8 pins into one byte.
• bool setPolarity8(uint8_t port, uint8_t mask) port = 0..1, sets polarity for 8 channels at once.
• bool getPolarity8(uint8_t port, uint8_t &mask) port = 0..1, reads polarity of 8 channels at once.
• bool setPullup8(uint8_t port, uint8_t mask) port = 0..1, sets pull-up for 8 channels at once.
• bool getPullup8(uint8_t port, uint8_t &mask) port = 0..1, reads pull-up for 8 channels at once.

16 pins interface

• bool pinMode16(uint16_t value) value = 0..0xFFFF, returns true if successful.
• bool write16(uint16_t value) value = 0..0xFFFF, returns true if successful.
• uint16_t read16() reads 16 pins into an uint16_t.
• bool setPolarity16(uint16_t mask) sets polarity for 16 channels.
• bool getPolarity16(uint16_t &mask) reads polarity of 16 channels.
• bool setPullup16(uint16_t mask) sets pull-up for 16 channels.
• bool getPullup16(uint16_t &mask) reads pull-up for 16 channels.

Error codes

• int lastError() Above functions set an error flag that can be read with this function.
  Reading it will reset the flag to MCP23017_OK.

DESCRIPTION	VALUE
MCP23017_OK	0x00
MCP23017_PIN_ERROR	0x81
MCP23017_I2C_ERROR	0x82
MCP23017_VALUE_ERROR	0x83
MCP23017_PORT_ERROR	0x84

Operation

See examples.

Future

Must

• Improve and extend documentation
• add examples

Should

• extend error codes
• optimize code - squeeze footprint
• optimize code - do not write if pin does not chance (~25%)

Could

• initial value (16 bit?) as begin parameter (breaking change)
  • depends on input output pull-up etc?
• investigate auto address increment?