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209 lines
6.9 KiB
Markdown
209 lines
6.9 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/MCP23S08/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/MCP23S08/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/MCP23S08/issues)
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[](https://github.com/RobTillaart/MCP23S08/blob/master/LICENSE)
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[](https://github.com/RobTillaart/MCP23S08/releases)
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[](https://registry.platformio.org/libraries/robtillaart/MCP23S08)
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# MCP23S08
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Arduino library for MCP23S08 8 channel SPI port expander.
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## Description
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This experimental library gives easy control over the 8 pins of a (SPI) MCP23S08 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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Since 0.1.1 the **digitalWrite(pin, value)** is optimized.
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If a pin is not changed it will not be written again to save time.
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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 "MCP23S08.h"
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```
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### Constructor
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- **MCP23S08(uint8_t select, uint8_t dataIn, uint8_t dataOut, uint8_t clock, uint8_t address = 0x00)** constructor SOFTWARE SPI.
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- **MCP23S08(uint8_t select, SPIClass\* spi)** constructor HARDWARE SPI with explicit SPI interface selected.
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- **MCP23S08(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..3.
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The two hardware constructors allow to call 4 different constructors.
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```cpp
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- MCP23S08(10); // select pin only
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- MCP23S08(10, 7); // select pin + address pins
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- MCP23S08(10, 7, &SPI2); // select pin + address pins + SPI port
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- MCP23S08(10, &SPI2); // select pin + SPI port
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```
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#### Sharing SELECT lines
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(verified in MCP23S17 issue 19)
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Technically two chips could use the same SELECT pin and a different address.
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Since 0.2.0 the constructors allow to setup such a configuration.
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The added value is that one can use up to 4 devices (= 32 IO lines) with only
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four lines (MISO, MOSI, CLOCK, SELECT).
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I assume that this configuration is less used and IMHO not recommended.
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NB it is more difficult to detect which device is selected when debugging.
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To use the hardware addresses the Hardware Address ENable register must be set.
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See datasheet 1.6.6 ADDRESSING SPI DEVICES, need to set IOCON.HAEN.
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The library supports two ways:
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```cpp
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MCP.enableControlRegister(MCP23S08_IOCR_HAEN); // or 0x08
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or
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MCP.enableHardwareAddress(); // 0.2.0 version and up
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```
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See also **IO Control Register** section below.
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### Single pin interface
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mode: 0 = OUTPUT, 1 = INPUT, 1 = INPUT_PULLUP (==INPUT)
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- **bool pinMode(uint8_t pin, uint8_t mode)** pin = 0..7.
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Returns true if successful.
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- **bool digitalWrite(uint8_t pin, uint8_t value)** pin = 0..7, value = LOW(0) HIGH (!0).
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Returns true if successful.
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- **uint8_t digitalRead(uint8_t pin)** pin = 0..7, returns LOW or HIGH, might set the lastError();
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- **bool setPolarity(uint8_t pin, bool reversed)** pin = 0..7, set reversed flag.
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Returns true if successful.
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- **bool getPolarity(uint8_t pin, bool &reversed)** pin = 0..7, reads reversed flag.
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Returns true if successful.
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- **bool setPullup(uint8_t pin, bool pullup)** pin = 0..7, set pull-up flag.
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Returns true if successful.
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- **bool getPullup(uint8_t pin, bool &pullup)** pin = 0..7, reads pull-up flag.
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Returns true if successful.
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### 8 pins interface
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- **bool pinMode8(uint8_t value)** value = 0..255. Returns true if successful.
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- **bool write8(uint8_t value)** value = 0..255. Returns true if successful.
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- **uint8_t read8()** reads 8 pins into one byte.
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- **bool setPolarity8(uint8_t mask)** sets polarity for 8 channels at once.
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Returns true if successful.
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- **bool getPolarity8(uint8_t &mask)** reads polarity of 8 channels at once.
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Returns true if successful.
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- **bool setPullup8(uint8_t mask)** sets pull-up for 8 channels at once.
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Returns true if successful.
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- **bool getPullup8(uint8_t &mask)** reads pull-up for 8 channels at once.
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Returns true if successful.
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### Other
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- **void setSPIspeed(uint32_t speed)** set hardware speed (8Mb default).
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- **uint32_t getSPIspeed()** returns set speed.
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### Debugging
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- **bool usesHWSPI()** returns true = hardware SPI, false = software SPI.
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- **int lastError()** idem.
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### ControlRegister
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Since 0.2.0
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- **void enableControlRegister(uint8_t mask)** set IOCR bit fields
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- **void disableControlRegister(uint8_t mask)** clear IOCR bit fields
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- **void enableHardwareAddress()** specific for HAEN field.
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- **void disableHardwareAddress()** specific for HAEN field.
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### ESP32
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Since 0.2.0
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- **void selectHSPI()** idem
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- **void selectVSPI()** idem
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- **bool usesHSPI()** idem
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- **bool usesVSPI()** idem
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- **void setGPIOpins(uint8_t clk, uint8_t miso, uint8_t mosi, uint8_t select)** overrule the ESP32s default hardware pins.
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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 **MCP23S08_OK**.
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| Name | Value | description |
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|:--------------------------|:-------:|:--------------|
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| MCP23S08_OK | 0x00 | No error |
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| MCP23S08_PIN_ERROR | 0x81 |
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| MCP23S08_SPI_ERROR | 0x82 |
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| MCP23S08_VALUE_ERROR | 0x83 |
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| MCP23S08_PORT_ERROR | 0x84 |
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| MCP23S08_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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- keep documentation in sync with MCP23S17
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#### Should
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- keep functional in sync with MCP23017_RT and MCP23S17
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#### Could
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- ESP32 example code
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#### Wont
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## Support
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If you appreciate my libraries, you can support the development and maintenance.
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Improve the quality of the libraries by providing issues and Pull Requests, or
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donate through PayPal or GitHub sponsors.
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Thank you,
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