koson/mcp23s17

Arduino library for SPI based MCP23S17 16 channel port expander

MCP23S17

Arduino library for MCP23S17 16 channel SPI port expander.

Description

This experimental library gives easy control over the 16 pins of a (SPI) MCP23S17 chip.

This IC is strongly related to the MCP23017 I2C port expander - https://github.com/RobTillaart/MCP23017_RT Programming Interface is kept the same as much as possible.

Interface

Constructor

• MCP23S17(uint8_t select, uint8_t data, uint8_t clock) constructor SW SPI
• MCP23S17(uint8_t select) constructor HW SPI
• bool begin() returns true if successful.
• bool isConnected() returns true if connected, false otherwise. (dummy)

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 MCP23S17_OK.

NAME	VALUE	DESCRIPTION
MCP23S17_OK	0x00	No error
MCP23S17_PIN_ERROR	0x81
MCP23S17_I2C_ERROR	0x82
MCP23S17_VALUE_ERROR	0x83
MCP23S17_PORT_ERROR	0x84

Operation

See examples.

Future

• keep functional in sync with MCP23017_RT
• isConnected() is not really needed
• implement ESP32 specific support - see MCP_ADC.begin()
• replace magic numbers with a defined constant