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183 lines
6.9 KiB
Markdown
183 lines
6.9 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/MCP23S17/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/MCP23S17/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/MCP23S17/blob/master/LICENSE)
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[](https://github.com/RobTillaart/MCP23S17/releases)
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# MCP23S17
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Arduino library for MCP23S17 16 channel SPI port expander.
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## Description
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This experimental library gives easy control over the 16 pins of a (SPI) MCP23S17 chip.
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This IC is strongly related to the MCP23017 I2C port expander - https://github.com/RobTillaart/MCP23017_RT
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Programming Interface is kept the same as much as possible.
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#### Related
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16 bit port expanders
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- https://github.com/RobTillaart/MCP23017_RT
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- https://github.com/RobTillaart/MCP23S17
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- https://github.com/RobTillaart/PCF8575
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8 bit port expanders
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- https://github.com/RobTillaart/MCP23008
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- https://github.com/RobTillaart/MCP23S08
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- https://github.com/RobTillaart/PCF8574
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## Interface
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```cpp
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#include "MCP23S17.h"
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```
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### Constructor
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- **MCP23S17(uint8_t select, uint8_t dataIn, uint8_t dataOut, uint8_t clock, uint8_t address = 0x00)** constructor SOFTWARE SPI.
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- **MCP23S17(uint8_t select, SPIClass\* spi)** constructor HARDWARE SPI with explicit SPI interface selected.
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- **MCP23S17(uint8_t select, uint8_t address = 0x00, SPIClass\* spi = &SPI)** constructor HARDWARE SPI with optional address pins and SPI interface.
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- **bool begin()** returns true if successful.
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- **bool isConnected()** returns true if connected, false otherwise. (dummy for compatibility reasons)
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- **uint8_t getAddress()** returns the address set in the constructor.
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Default = 0, range = 0..7.
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The two hardware constructors allow to call 4 different constructors.
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```cpp
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- MCP23S17(10); // select pin only
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- MCP23S17(10, 7); // select pin + address pins
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- MCP23S17(10, 7, &SPI2); // select pin + address pins + SPI port
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- MCP23S17(10, &SPI2); // select pin + SPI port
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```
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#### sharing select lines
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(not tested)
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Technically two chips could use the same select pin and a different address.
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The constructors would allow to setup such a configuration.
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I assume that this is less used and IMHO not recommended.
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### Single pin interface
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- **bool pinMode(uint8_t pin, uint8_t mode)** pin = 0..15, mode = INPUT, OUTPUT. Returns true if successful.
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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 LOW or HIGH, might set the lastError();
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- **bool setPolarity(uint8_t pin, bool reversed)** pin = 0..15, set reversed flag. Returns true if successful.
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- **bool getPolarity(uint8_t pin, bool &reversed)** pin = 0..15, reads reversed flag. Returns true if successful.
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- **bool setPullup(uint8_t pin, bool pullup)** pin = 0..15, set pull-up flag. Returns true if successful.
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- **bool getPullup(uint8_t pin, bool &pullup)** pin = 0..15, reads pull-up flag. Returns true if successful.
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### 8 pins interface
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- **bool pinMode8(uint8_t port, uint8_t value)** port = 0..1, value = 0..255. Returns true if successful.
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- **bool write8(uint8_t port, uint8_t value)** port = 0..1, value = 0..255. Returns true if successful.
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- **uint8_t read8(uint8_t port)** port = 0..1, reads 8 pins into one byte.
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- **bool setPolarity8(uint8_t port, uint8_t mask)** port = 0..1, sets polarity for 8 channels at once.
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Returns true if successful.
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- **bool getPolarity8(uint8_t port, uint8_t &mask)** port = 0..1, reads polarity of 8 channels at once.
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Returns true if successful.
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- **bool setPullup8(uint8_t port, uint8_t mask)** port = 0..1, sets pull-up for 8 channels at once.
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Returns true if successful.
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- **bool getPullup8(uint8_t port, uint8_t &mask)** port = 0..1, reads pull-up for 8 channels at once.
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Returns true if successful.
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### 16 pins interface
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- **bool pinMode16(uint16_t value)** value = 0..0xFFFF, returns true if successful.
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Returns true if successful.
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- **bool write16(uint16_t value)** value = 0..0xFFFF, returns true if successful.
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Returns true if successful.
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- **uint16_t read16()** reads 16 pins into an uint16_t.
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- **bool setPolarity16(uint16_t mask)** sets polarity for 16 channels.
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Returns true if successful.
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- **bool getPolarity16(uint16_t &mask)** reads polarity of 16 channels.
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Returns true if successful.
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- **bool setPullup16(uint16_t mask)** sets pull-up for 16 channels.
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Returns true if successful.
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- **bool getPullup16(uint16_t &mask)** reads pull-up for 16 channels.
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Returns true if successful.
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### IO Control Register
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Since 0.2.3 the library supports setting bit fields in the IO control register.
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Read the datasheet carefully!
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- **void enableControlRegister(uint8_t mask)**
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- **void disableControlRegister(uint8_t mask)**
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| constant | mask | description |
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|:-----------------------|:------:|:--------------|
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| MCP23S17_IOCR_BANK | 0x80 | Controls how the registers are addressed.
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| MCP23S17_IOCR_MIRROR | 0x40 | INT Pins Mirror bit.
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| MCP23S17_IOCR_SEQOP | 0x20 | Sequential Operation mode bit.
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| MCP23S17_IOCR_DISSLW | 0x10 | Slew Rate control bit for SDA output.
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| MCP23S17_IOCR_HAEN | 0x08 | Hardware Address Enable bit (MCP23S17 only).
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| MCP23S17_IOCR_ODR | 0x04 | Configures the INT pin as an open-drain output.
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| MCP23S17_IOCR_INTPOL | 0x02 | This bit sets the polarity of the INT output pin.
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| MCP23S17_IOCR_NI | 0x01 | Not implemented.
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### Error codes
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If one of the above functions return false, there might be an error.
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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 **MCP23S17_OK**.
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| name | value | description |
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|:--------------------------|:-------:|:--------------|
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| MCP23S17_OK | 0x00 | No error |
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| MCP23S17_PIN_ERROR | 0x81 |
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| MCP23S17_I2C_ERROR | 0x82 | (compatibility)
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| MCP23S17_VALUE_ERROR | 0x83 |
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| MCP23S17_PORT_ERROR | 0x84 |
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| MCP23S17_REGISTER_ERROR | 0xFF | low level.
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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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- improve documentation
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#### Should
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- keep functional in sync with MCP23017_RT
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#### Could
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- check need for writing in all functions (Polarity / pullup)
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- check if bit mask changes.
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- what is performance gain vs footprint?
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- implement ESP32 specific support in begin()
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- see MCP_ADC.begin()
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- SW_SPI is roughly equal in performance as HW SPI on ESP32.
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- investigate and reimplement the INPUT_PULLUP for pinMode() ?
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#### Wont
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- check address range in constructor.
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