114 lines
2.5 KiB
Markdown
114 lines
2.5 KiB
Markdown
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# MCP23008 Module
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| Since | Origin / Contributor | Maintainer | Source |
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| :----- | :-------------------- | :---------- | :------ |
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| 2015-03-02 | [AllAboutEE](https://github.com/AllAboutEE) | [AllAboutEE](https://github.com/AllAboutEE) | [mcp23008.lua](../../lua_modules/mcp23008/mcp23008.lua) |
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This Lua module provides access to [MCP23008](http://ww1.microchip.com/downloads/en/DeviceDoc/21919e.pdf) I²C I/O Expander.
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!!! note
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This module requires `i2c` C module built into firmware.
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### Require
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```lua
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mcp32008 = require("mcp32008")
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```
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### Release
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```lua
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mcp32008 = nil
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package.loaded["mcp32008"] = nil
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```
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## mcp32008.begin()
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Sets the MCP23008 device address's last three bits.
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!!! note
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The address is defined as binary `0100[A2][A1][A0]` where `A2`, `A1`, and `A0` are defined by the connection of the pins, e.g. if the pins are connected all to GND then the parameter address will need to be `0x0`.
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#### Syntax
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`mcp23008.begin(address, pinSDA, pinSCL, speed)`
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#### Parameters
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- `address`: The 3 least significant bits (LSB) of the address
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- `pinSDA`: The pin to use for SDA
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- `pinSCL`: The pin to use for SCL
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- `speed`: The speed of the I2C signal
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#### Returns
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`nil`
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## mcp23008.writeGPIO()
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Writes a byte of data to the GPIO register.
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#### Syntax
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`mcp23008.writeGPIO(dataByte)`
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#### Parameters
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- `dataByte`: The byte of data to write
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#### Returns
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`nil`
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## mcp23008.readGPIO()
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Reads a byte of data from the GPIO register
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#### Syntax
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`mcp23008.readGPIO()`
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#### Parameters
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None
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#### Returns
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One byte of data
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## mcp23008.writeIODIR()
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Writes one byte of data to the IODIR register.
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#### Syntax
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`mcp23008.writeIODIR(dataByte)`
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#### Parameters
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- `dataByte`: The byte of data to write
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#### Returns
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`nil`
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## mcp23008.readIODIR()
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Reads a byte from the IODIR register
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#### Syntax
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`mcp23008.readIODIR()`
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#### Parameters
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None
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#### Returns
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The byte of data in IODIR
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## mcp23008.writeGPPU()
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Writes a byte of data to the GPPU (Pull-UP resistors register)
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#### Syntax
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`mcp23008.writeIODIR(dataByte)`
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#### Parameters
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- `dataByte`: the value to write to the GPPU register. Each bit in this byte is assigned to an individual GPIO pin
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#### Returns
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`nil`
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## mcp23008.readGPPU()
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Reads the GPPU (Pull-UP resistors register) byte
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#### Syntax
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`mcp23008.readGPPU()`
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#### Parameters
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None
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#### Returns
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The GPPU byte i.e. state of all internal pull-up resistors
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#### Notes
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Other examples of using this module can be found in [mcp23008_buttons.lua](../../lua_examples/mcp23008/mcp23008_buttons.lua) and [mcp23008_leds.lua](../../lua_examples/mcp23008/mcp23008_leds.lua) files.
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