pca9535

https://docs.rs/pca9535
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PCA9535 is a Rust driver library for the PCA9535 16-bit IO-expander device using the embedded-hal...
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### PinState Conversion and Negation Example

Source: https://docs.rs/pca9535/latest/pca9535/enum.PinState.html

Demonstrates converting a boolean to PinState and performing logical negation. Use this to easily manage pin states.

```rust
let state = PinState::from(false);
assert_eq!(state, PinState::Low);
assert_eq!(!state, PinState::High);
```

--------------------------------

### Configure and Set Pin using Standard Interface

Source: https://docs.rs/pca9535

Demonstrates using the `StandardExpanderInterface` to configure a pin as output and set its state to high. The user must ensure the pin's configuration (input/output) before use.

```rust
use rppal::i2c::I2c;
use pca9535::GPIOBank;
use pca9535::StandardExpanderInterface;
use pca9535::Pca9535Immediate;

let i2c = I2c::new().unwrap();
let address = 32;

let mut expander = Pca9535Immediate::new(i2c, address); //Either Immediate or Cached expander

expander.pin_into_output(GPIOBank::Bank0, 3).unwrap();
expander.pin_set_high(GPIOBank::Bank0, 3).unwrap();
// and so on...
```

--------------------------------

### Get cached register value

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/cached.rs.html

Retrieves the cached value for a specified register. This method does not perform any I2C bus transactions.

```rust
fn get_cached(&self, register: Register) -> u8 {
        match register {
            Register::InputPort0 => self.input_port_0,
            Register::InputPort1 => self.input_port_1,
            Register::OutputPort0 => self.output_port_0,
            Register::OutputPort1 => self.output_port_1,
            Register::PolarityInversionPort0 => self.polarity_inversion_port_0,
            Register::PolarityInversionPort1 => self.polarity_inversion_port_1,
            Register::ConfigurationPort0 => self.configuration_port_0,
            Register::ConfigurationPort1 => self.configuration_port_1,
        }
    }
```

--------------------------------

### Initialize PCA9535 Immediate Expander

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/immediate.rs.html

Creates a new instance of the PCA9535 immediate expander. Panics if the device hardware address is outside the range of 32-39.

```rust
pub fn new(i2c: I2C, address: u8) -> Self {
        assert!(address > 31 && address < 40);

        Self { address, i2c }
    }
```

--------------------------------

### Create new PCA9535Cached instance

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/cached.rs.html

Initializes a new cached PCA9535 instance. If `init_defaults` is false, it reads all device registers to populate the cache. Use `init_defaults = true` only if no prior transactions have been made with the device to avoid unexpected behavior. Panics if the device address is out of range (32-39).

```rust
pub fn new(
        i2c: I2C,
        address: u8,
        interrupt_pin: IP,
        init_defaults: bool,
    ) -> Result<Self, ExpanderError<E>> {
        assert!(address > 31 && address < 40);

        let mut expander = Self {
            address,
            i2c,
            interrupt_pin,
            input_port_0: 0x00,
            input_port_1: 0x00,
            output_port_0: 0xFF,
            output_port_1: 0xFF,
            polarity_inversion_port_0: 0x00,
            polarity_inversion_port_1: 0x00,
            configuration_port_0: 0xFF,
            configuration_port_1: 0xFF,
        };

        if !init_defaults {
            Self::init_cache(&mut expander)?;
        }

        Ok(expander)
    }
```

--------------------------------

### IoExpander::new

Source: https://docs.rs/pca9535/latest/pca9535/expander/io/struct.IoExpander.html

Creates a new IoExpander instance from an existing Expander.

```APIDOC
## IoExpander::new

### Description
Creates a new IoExpander instance out of an Expander.

### Signature
```rust
pub fn new(expander: Ex) -> IoExpander<I2C, Ex, Em>
```

### Type Parameters
* `I2C`: The I2C trait bound.
* `Ex`: The Expander trait bound.
* `Em`: The ExpanderMutex trait bound.

### Parameters
* `expander`: An instance of the Expander.

### Returns
A new `IoExpander` instance.
```

--------------------------------

### Create and Use PCA9535 HAL Pins

Source: https://docs.rs/pca9535

Demonstrates creating input and output pins from a wrapped PCA9535 expander and manipulating their state. Ensure the `std` feature is enabled for `Mutex`.

```rust
use std::sync::Mutex;
use rppal::i2c::I2c;
use hal::digital::{InputPin, OutputPin};
use pca9535::IoExpander;
use pca9535::Pca9535Immediate;
use pca9535::{ExpanderInputPin, ExpanderOutputPin};
use pca9535::GPIOBank::{Bank0, Bank1};
use pca9535::PinState;

let i2c = I2c::new().unwrap();
let address = 32;

let mut expander = Pca9535Immediate::new(i2c, address);

let io_expander: IoExpander<_, _, Mutex<_>> = IoExpander::new(expander);

let mut expander_pin_1_5 = ExpanderInputPin::new(&io_expander, Bank1, 5).unwrap();
let mut expander_pin_0_2 = ExpanderOutputPin::new(&io_expander, Bank0, 2, PinState::Low).unwrap();

expander_pin_0_2.set_high();
let is_high = expander_pin_1_5.is_high();
// and so on...
```

--------------------------------

### Initialize PCA9535 Expander with HAL Traits

Source: https://docs.rs/pca9535

Initializes a PCA9535 expander and wraps it in an `IoExpander` for use with standard `hal` traits. Requires the `std` feature to be enabled for `Mutex`.

```rust
use std::sync::Mutex;
use rppal::i2c::I2c;
use pca9535::IoExpander;
use pca9535::Pca9535Immediate;

let i2c = I2c::new().unwrap();
let address = 32;

let mut expander = Pca9535Immediate::new(i2c, address); //Either Immediate or Cached expander

let io_expander: IoExpander<_, _, Mutex<_>> = IoExpander::new(expander); // Wrapped expander in std environment using Mutex as ExpanderMutex
```

--------------------------------

### IoExpander::new Constructor

Source: https://docs.rs/pca9535/latest/pca9535/expander/io/struct.IoExpander.html

Creates a new IoExpander instance from an existing Expander. This is the primary way to obtain a Sync-compatible Expander.

```rust
pub fn new(expander: Ex) -> IoExpander<I2C, Ex, Em>
```

--------------------------------

### IoExpander::new

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/io.rs.html

Creates a new IoExpander instance by wrapping an existing Expander in a mutex.

```APIDOC
## IoExpander::new

### Description
Creates a new `IoExpander` instance out of an `Expander`.

### Signature
```rust
pub fn new(expander: Ex) -> IoExpander<I2C, Ex, Em>
```

### Parameters
* `expander`: The `Expander` instance to wrap.
```

--------------------------------

### Pca9535Immediate::new

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/immediate.rs.html

Creates a new immediate PCA9535 instance. Panics if the device hardware address is outside the range of 32-39.

```APIDOC
## Pca9535Immediate::new

### Description
Creates a new immediate PCA9535 instance.

### Parameters
- **i2c** (I2C): The I2C peripheral to use.
- **address** (u8): The hardware address of the PCA9535 device. Must be between 32 and 39 (inclusive).

### Panics
This function will panic if the provided `address` is not within the valid range of 32 to 39.
```

--------------------------------

### Pca9535Immediate::new

Source: https://docs.rs/pca9535/latest/pca9535/expander/immediate/struct.Pca9535Immediate.html

Creates a new immediate PCA9535 instance. Panics if the device hardware address is outside the range of 32-39.

```APIDOC
## Pca9535Immediate::new

### Description
Creates a new immediate PCA9535 instance.

### Parameters
- **i2c** (I2C): The I2C bus to use.
- **address** (u8): The hardware address of the PCA9535 device.

### Panics
If the given device hardware address is outside the permittable range of `32-39`.
```

--------------------------------

### Configure Pin as Output

Source: https://docs.rs/pca9535/latest/pca9535/expander/immediate/struct.Pca9535Immediate.html

Configures a specific pin to operate as an output.

```rust
fn pin_into_output( &mut self, bank: GPIOBank, pin: u8, ) -> Result<(), ExpanderError<E>>
```

--------------------------------

### pin_into_output

Source: https://docs.rs/pca9535/latest/pca9535/expander/standard/trait.StandardExpanderInterface.html

Configures the specified pin as an output.

```APIDOC
## pin_into_output

### Description
Configures the specified pin as an output.

### Signature
```rust
fn pin_into_output(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>
```

### Parameters
* `bank`: The GPIO bank (e.g., `GPIOBank::Bank1`).
* `pin`: The pin number (0-7).

### Returns
* `Ok(())` on success.
* `Err(ExpanderError<E>)` on failure.

### Panics
Panics if the provided pin is not in the allowed range of 0-7.
```

--------------------------------

### Create PCA9535 Input Pin

Source: https://docs.rs/pca9535/latest/src/pca9535/pin.rs.html

Initializes a new input pin for the PCA9535 expander. Panics if the pin number is out of range (0-7).

```rust
pub fn new(expander: &'a Io, bank: GPIOBank, pin: u8) -> Result<Self, ExpanderError<E>> {
        assert!(pin < 8);

        let register = match bank {
            GPIOBank::Bank0 => Register::ConfigurationPort0,
            GPIOBank::Bank1 => Register::ConfigurationPort1,
        };

        let mut reg_val: u8 = 0x00;

        expander.read_byte(register, &mut reg_val)?;
        expander.write_byte(register, reg_val | (0x01 << pin))?;

        Ok(Self {
            expander,
            bank,
            pin,
            phantom_data: PhantomData,
        })
    }
```

--------------------------------

### From Trait Implementation

Source: https://docs.rs/pca9535/latest/pca9535/expander/immediate/struct.Pca9535Immediate.html

Allows creating an instance from another value of the same type.

```APIDOC
## impl<T> From<T> for T

### Description
Provides a way to create a value of type `T` from another value of type `T`.

### fn from(t: T) -> T

#### Description
Returns the argument unchanged.

#### Parameters
- `t: T`: The value to convert from.

#### Returns
- `T`: The converted value (which is the same as the input).
```

--------------------------------

### ExpanderOutputPin::new Constructor

Source: https://docs.rs/pca9535/latest/pca9535/pin/struct.ExpanderOutputPin.html

Creates a new output pin instance. Panics if the provided pin number is outside the valid range of 0-7.

```rust
pub fn new(
    expander: &'a Io,
    bank: GPIOBank,
    pin: u8,
    state: PinState,
) -> Result<Self, ExpanderError<E>>
```

--------------------------------

### Create Pca9535Cached Instance

Source: https://docs.rs/pca9535/latest/pca9535/expander/cached/struct.Pca9535Cached.html

Creates a new cached PCA9535 instance. Use `init_defaults = true` if no prior transactions have been made with the device. Setting `init_defaults` to `false` reads existing register values from the device.

```rust
pub fn new( i2c: I2C, address: u8, interrupt_pin: IP, init_defaults: bool, ) -> Result<Self, ExpanderError<E>>
```

--------------------------------

### Configure PCA9535 Pin as Output

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/standard.rs.html

Configures the specified pin as an output. Panics if the pin is out of the 0-7 range.

```rust
    fn pin_into_output(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>> {
        assert!(pin < 8);

        let register = match bank {
            GPIOBank::Bank0 => Register::ConfigurationPort0,

```

--------------------------------

### IoExpander::new Constructor

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/io.rs.html

Creates a new `IoExpander` instance. This constructor takes ownership of an `Expander` and wraps it in a mutex, making it ready for synchronized use.

```rust
pub fn new(expander: Ex) -> IoExpander<I2C, Ex, Em> {
    IoExpander {
        expander_mutex: Em::new(expander),
        phantom_data: PhantomData,
        phantom_data_2: PhantomData,
    }
}
```

--------------------------------

### Pca9535Immediate Initialization

Source: https://docs.rs/pca9535/latest/index.html

Initializes the PCA9535 expander in immediate mode, issuing an I2C bus transaction on each function call.

```APIDOC
## Pca9535Immediate Initialization

### Description
Initializes the PCA9535 expander in immediate mode. This mode issues an I2C bus transaction on each function call that changes the state of the expander. It does not utilize the open-drain interrupt output of the device to minimize bus traffic and does not maintain internal state of the device registers.

### Method
`Pca9535Immediate::new(i2c, address)`

### Parameters
- **i2c**: An I2C bus instance implementing the `embedded-hal` traits.
- **address**: The 7-bit I2C address of the PCA9535 device.

### Request Example
```rust
use rppal::i2c::I2c;
use pca9535::Pca9535Immediate;

let i2c = I2c::new().unwrap();
let address = 32;

let expander = Pca9535Immediate::new(i2c, address);
```
```

--------------------------------

### Configure Pin as Input

Source: https://docs.rs/pca9535/latest/pca9535/expander/immediate/struct.Pca9535Immediate.html

Configures a specific pin to operate as an input.

```rust
fn pin_into_input( &mut self, bank: GPIOBank, pin: u8, ) -> Result<(), ExpanderError<E>>
```

--------------------------------

### ExpanderOutputPin::new

Source: https://docs.rs/pca9535/latest/pca9535/pin/struct.ExpanderOutputPin.html

Creates a new output pin instance for the PCA9535 expander. It requires a reference to the expander, the bank, the pin number, and the initial state. Panics if the pin number is out of the valid range (0-7).

```APIDOC
## ExpanderOutputPin::new

### Description
Creates a new output pin.

### Parameters
- `expander`: A reference to the `SyncExpander` instance.
- `bank`: The `GPIOBank` to which the pin belongs.
- `pin`: The pin number (0-7).
- `state`: The initial `PinState` of the pin.

### Returns
A `Result` containing the new `ExpanderOutputPin` instance or an `ExpanderError`.

### Panics
Panics if the provided pin is not in the allowed range of 0-7.
```

--------------------------------

### StandardExpanderInterface

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/standard.rs.html

The `StandardExpanderInterface` trait provides a set of methods for interacting with the PCA9535 expander without relying on the `hal` crate. It allows users to control pin states, configure pins as input or output, and read pin states.

```APIDOC
## Trait: StandardExpanderInterface<I2C, E>

### Description
Provides a standard interface for PCA9535 expander operations, independent of the `hal` crate. This trait requires the implementor to manage pin state configurations manually.

### Methods

#### `pin_set_high(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`

Sets the specified pin in the given bank to a high logic level.

- **bank** (`GPIOBank`): The GPIO bank (Bank0 or Bank1).
- **pin** (`u8`): The pin number (0-7).

#### `pin_set_low(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`

Sets the specified pin in the given bank to a low logic level.

- **bank** (`GPIOBank`): The GPIO bank (Bank0 or Bank1).
- **pin** (`u8`): The pin number (0-7).

#### `pin_is_high(&mut self, bank: GPIOBank, pin: u8) -> Result<bool, ExpanderError<E>>`

Checks if the input state of the specified pin in the given bank is high. This reflects the value in the input register, which can be affected by polarity inversion.

- **bank** (`GPIOBank`): The GPIO bank (Bank0 or Bank1).
- **pin** (`u8`): The pin number (0-7).

#### `pin_is_low(&mut self, bank: GPIOBank, pin: u8) -> Result<bool, ExpanderError<E>>`

Checks if the input state of the specified pin in the given bank is low. This reflects the value in the input register, which can be affected by polarity inversion.

- **bank** (`GPIOBank`): The GPIO bank (Bank0 or Bank1).
- **pin** (`u8`): The pin number (0-7).

#### `pin_into_input(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`

Configures the specified pin in the given bank as an input.

- **bank** (`GPIOBank`): The GPIO bank (Bank0 or Bank1).
- **pin** (`u8`): The pin number (0-7).

#### `pin_into_output(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`

Configures the specified pin in the given bank as an output.

- **bank** (`GPIOBank`): The GPIO bank (Bank0 or Bank1).
- **pin** (`u8`): The pin number (0-7).

### Panics
Functions within this trait will panic if the provided pin number is outside the valid range of 0-7.
```

--------------------------------

### Create ExpanderInputPin

Source: https://docs.rs/pca9535/latest/pca9535/pin/struct.ExpanderInputPin.html

Instantiates a new input pin for the PCA9535 expander. Panics if the pin number is out of the valid range (0-7).

```rust
pub fn new( expander: &'a Io, bank: GPIOBank, pin: u8, ) -> Result<Self, ExpanderError<E>>
```

--------------------------------

### pin_into_input

Source: https://docs.rs/pca9535/latest/pca9535/expander/standard/trait.StandardExpanderInterface.html

Configures the specified pin as an input.

```APIDOC
## pin_into_input

### Description
Configures the specified pin as an input.

### Signature
```rust
fn pin_into_input(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>
```

### Parameters
* `bank`: The GPIO bank (e.g., `GPIOBank::Bank1`).
* `pin`: The pin number (0-7).

### Returns
* `Ok(())` on success.
* `Err(ExpanderError<E>)` on failure.

### Panics
Panics if the provided pin is not in the allowed range of 0-7.
```

--------------------------------

### Configure PCA9535 Pin as Input

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/standard.rs.html

Configures the specified pin as an input. Panics if the pin is out of the 0-7 range.

```rust
    fn pin_into_input(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>> {
        assert!(pin < 8);

        let register = match bank {
            GPIOBank::Bank0 => Register::ConfigurationPort0,
            GPIOBank::Bank1 => Register::ConfigurationPort1,
        };

        let mut reg_val: u8 = 0x00;

        self.read_byte(register, &mut reg_val)?;

        self.write_byte(register, reg_val | (0x01 << pin))
    }
```

--------------------------------

### Initialize PCA9535 cache

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/cached.rs.html

Reads all necessary device registers to initialize the internal cache. This is used when `init_defaults` is false during `new`. Errors are mapped to `ExpanderError::WriteReadError`.

```rust
fn init_cache(expander: &mut Self) -> Result<(), ExpanderError<E>> {
        let mut buf: [u8; 2] = [0x00, 0x00];

        expander
            .i2c
            .write_read(
                expander.address,
                &[Register::ConfigurationPort0 as u8],
                &mut buf,
            )
            .map_err(ExpanderError::WriteReadError)?;
        expander.configuration_port_0 = buf[0];
        expander.configuration_port_1 = buf[1];

        expander
            .i2c
            .write_read(expander.address, &[Register::InputPort0 as u8], &mut buf)
            .map_err(ExpanderError::WriteReadError)?;
        expander.input_port_0 = buf[0];
        expander.input_port_1 = buf[1];

        expander
            .i2c
            .write_read(expander.address, &[Register::OutputPort0 as u8], &mut buf)
            .map_err(ExpanderError::WriteReadError)?;
        expander.output_port_0 = buf[0];
        expander.output_port_1 = buf[1];

        expander
            .i2c
            .write_read(
                expander.address,
                &[Register::PolarityInversionPort0 as u8],
                &mut buf,
            )
            .map_err(ExpanderError::WriteReadError)?;
        expander.polarity_inversion_port_0 = buf[0];
        expander.polarity_inversion_port_1 = buf[1];

        Ok(())
    }
```

--------------------------------

### StandardExpanderInterface Trait Methods

Source: https://docs.rs/pca9535/latest/pca9535/expander/immediate/struct.Pca9535Immediate.html

Standard GPIO interface methods for controlling pins on the PCA9535 expander.

```APIDOC
## StandardExpanderInterface Trait Methods

### pin_set_high

#### Description
Sets the specified pin to a high logic level.

#### Parameters
- **bank** (GPIOBank): The GPIO bank the pin belongs to.
- **pin** (u8): The pin number within the bank.

#### Returns
- Result<(), ExpanderError<E>>: Ok(()) on success, or an error.

### pin_set_low

#### Description
Drives the specified pin to a low logic level.

#### Parameters
- **bank** (GPIOBank): The GPIO bank the pin belongs to.
- **pin** (u8): The pin number within the bank.

#### Returns
- Result<(), ExpanderError<E>>: Ok(()) on success, or an error.

### pin_is_high

#### Description
Checks if the input state of the given pin is high. Works for both input and output pins.

#### Parameters
- **bank** (GPIOBank): The GPIO bank the pin belongs to.
- **pin** (u8): The pin number within the bank.

#### Returns
- Result<bool, ExpanderError<E>>: `Ok(true)` if the pin is high, `Ok(false)` if low, or an error.

### pin_is_low

#### Description
Checks if the input state of the given pin is low. Works for both input and output pins.

#### Parameters
- **bank** (GPIOBank): The GPIO bank the pin belongs to.
- **pin** (u8): The pin number within the bank.

#### Returns
- Result<bool, ExpanderError<E>>: `Ok(true)` if the pin is low, `Ok(false)` if high, or an error.

### pin_into_input

#### Description
Configures the specified pin as an input.

#### Parameters
- **bank** (GPIOBank): The GPIO bank the pin belongs to.
- **pin** (u8): The pin number within the bank.

#### Returns
- Result<(), ExpanderError<E>>: Ok(()) on success, or an error.

### pin_into_output

#### Description
Configures the specified pin as an output.

#### Parameters
- **bank** (GPIOBank): The GPIO bank the pin belongs to.
- **pin** (u8): The pin number within the bank.

#### Returns
- Result<(), ExpanderError<E>>: Ok(()) on success, or an error.

### pin_inverse_polarity

#### Description
Sets the input polarity of the specified pin to inverted.

#### Parameters
- **bank** (GPIOBank): The GPIO bank the pin belongs to.
- **pin** (u8): The pin number within the bank.

#### Returns
- Result<(), ExpanderError<E>>: Ok(()) on success, or an error.

### pin_normal_polarity

#### Description
Sets the input polarity of the specified pin to normal.

#### Parameters
- **bank** (GPIOBank): The GPIO bank the pin belongs to.
- **pin** (u8): The pin number within the bank.

#### Returns
- Result<(), ExpanderError<E>>: Ok(()) on success, or an error.

### inverse_polarity

#### Description
Sets the input polarity of all pins to inverted.

#### Returns
- Result<(), ExpanderError<E>>: Ok(()) on success, or an error.

### normal_polarity

#### Description
Sets the input polarity of all pins to normal.

#### Returns
- Result<(), ExpanderError<E>>: Ok(()) on success, or an error.
```

--------------------------------

### Pin Configuration and State

Source: https://docs.rs/pca9535/latest/pca9535/expander/cached/struct.Pca9535Cached.html

Functions for configuring pin direction, polarity, and checking input state.

```APIDOC
## fn pin_is_low

### Description
Checks if the input state of the given pin is `low`. This function works with pins configured as inputs as well as outputs.

### Signature
`fn pin_is_low(&mut self, bank: GPIOBank, pin: u8) -> Result<bool, ExpanderError<E>>`

### Parameters
- `bank`: The GPIO bank (e.g., `GPIOBank::Bank1`, `GPIOBank::Bank2`).
- `pin`: The pin number (0-7).

### Returns
A `Result` containing `true` if the pin is low, `false` otherwise, or an `ExpanderError`.

## fn pin_into_input

### Description
Configures the given pin as an input.

### Signature
`fn pin_into_input(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`

### Parameters
- `bank`: The GPIO bank.
- `pin`: The pin number (0-7).

### Returns
A `Result` indicating success or an `ExpanderError`.

## fn pin_into_output

### Description
Configures the given pin as an output.

### Signature
`fn pin_into_output(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`

### Parameters
- `bank`: The GPIO bank.
- `pin`: The pin number (0-7).

### Returns
A `Result` indicating success or an `ExpanderError`.

## fn pin_inverse_polarity

### Description
Sets the input polarity of the given pin to inverted.

### Signature
`fn pin_inverse_polarity(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`

### Parameters
- `bank`: The GPIO bank.
- `pin`: The pin number (0-7).

### Returns
A `Result` indicating success or an `ExpanderError`.

## fn pin_normal_polarity

### Description
Sets the input polarity of the given pin to normal.

### Signature
`fn pin_normal_polarity(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`

### Parameters
- `bank`: The GPIO bank.
- `pin`: The pin number (0-7).

### Returns
A `Result` indicating success or an `ExpanderError`.
```

--------------------------------

### Create PCA9535 Output Pin

Source: https://docs.rs/pca9535/latest/src/pca9535/pin.rs.html

Initializes a new output pin for the PCA9535 expander, setting its initial state to high or low. Panics if the pin number is out of range (0-7).

```rust
pub fn new(
        expander: &'a Io,
        bank: GPIOBank,
        pin: u8,
        state: PinState,
    ) -> Result<Self, ExpanderError<E>> {
        assert!(pin < 8);

        let cp_register = match bank {
            GPIOBank::Bank0 => Register::ConfigurationPort0,
            GPIOBank::Bank1 => Register::ConfigurationPort1,
        };

        let op_register = match bank {
            GPIOBank::Bank0 => Register::OutputPort0,
            GPIOBank::Bank1 => Register::OutputPort1,
        };

        let mut reg_val: u8 = 0x00;

        expander.read_byte(op_register, &mut reg_val)?;

        if let PinState::High = state {
            expander.write_byte(op_register, reg_val | (0x01 << pin))?;
        } else {
            expander.write_byte(op_register, reg_val & !(0x01 << pin))?;
        }

        expander.read_byte(cp_register, &mut reg_val)?;

        expander.write_byte(cp_register, reg_val & !(0x01 << pin))?;

        Ok(Self {
            expander,
            bank,
            pin,
            phantom_data: PhantomData,
        })
    }
```

--------------------------------

### ExpanderInputPin::new

Source: https://docs.rs/pca9535/latest/pca9535/pin/struct.ExpanderInputPin.html

Creates a new input pin instance. Panics if the pin number is out of the valid range (0-7).

```APIDOC
## pub fn new

### Description
Create a new input pin

### Parameters
- **expander**: &'a Io - A reference to the SyncExpander instance.
- **bank**: GPIOBank - The GPIO bank the pin belongs to.
- **pin**: u8 - The pin number (0-7).

### Returns
- Result<Self, ExpanderError<E>> - A new ExpanderInputPin instance or an error.

### Panics
The function will panic if the provided pin is not in the allowed range of 0-7
```

--------------------------------

### Initialize Immediate PCA9535 Expander

Source: https://docs.rs/pca9535

Instantiates the `Pca9535Immediate` interface, which performs an I2C transaction for each function call. This is suitable when minimizing bus traffic is not critical.

```rust
use rppal::i2c::I2c;
use pca9535::Pca9535Immediate;

let i2c = I2c::new().unwrap();
let address = 32;

let expander = Pca9535Immediate::new(i2c, address);
```

--------------------------------

### InputPin Trait Implementations

Source: https://docs.rs/pca9535/latest/pca9535/pin/struct.ExpanderInputPin.html

Provides methods for reading the state of the input pin.

```APIDOC
## impl InputPin for ExpanderInputPin

### Description
Provides methods for reading the state of the input pin.

### Methods
#### fn is_high(&mut self) -> Result<bool, Self::Error>
Is the input pin high?

#### fn is_low(&mut self) -> Result<bool, Self::Error>
Is the input pin low?
```

--------------------------------

### StandardExpanderInterface Operations

Source: https://docs.rs/pca9535/latest/pca9535

Provides standard methods for interacting with the PCA9535 expander, regardless of the operation mode (Immediate or Cached).

```APIDOC
## StandardExpanderInterface

### Description
This trait provides a common interface for interacting with the PCA9535 expander, allowing users to configure pins and set their states.

### Methods
- `pin_into_output(bank: GPIOBank, pin: u8)`: Configures a specific pin as an output.
- `pin_set_high(bank: GPIOBank, pin: u8)`: Sets a specific output pin to a high state.
- `pin_set_low(bank: GPIOBank, pin: u8)`: Sets a specific output pin to a low state.
- `pin_read(bank: GPIOBank, pin: u8)`: Reads the current state of a pin (input or output).
- `pin_into_input(bank: GPIOBank, pin: u8)`: Configures a specific pin as an input.
- `pin_toggle_high(bank: GPIOBank, pin: u8)`: Toggles a specific output pin from low to high.
- `pin_toggle_low(bank: GPIOBank, pin: u8)`: Toggles a specific output pin from high to low.
- `set_polarity_inversion(bank: GPIOBank, pin: u8, invert: bool)`: Enables or disables polarity inversion for a pin.
- `set_all_pins_into_output()`: Configures all pins as outputs.
- `set_all_pins_into_input()`: Configures all pins as inputs.
- `set_all_pins_high()`: Sets all output pins to high.
- `set_all_pins_low()`: Sets all output pins to low.

### Parameters
- `bank`: The GPIO bank (Bank0 or Bank1).
- `pin`: The pin number within the bank (0-7).
- `invert`: Boolean to enable/disable polarity inversion.

### Request Example
```rust
use rppal::i2c::I2c;
use pca9535::{GPIOBank, StandardExpanderInterface, Pca9535Immediate};

let i2c = I2c::new().unwrap();
let address = 32;

let mut expander = Pca9535Immediate::new(i2c, address);

expander.pin_into_output(GPIOBank::Bank0, 3).unwrap();
expander.pin_set_high(GPIOBank::Bank0, 3).unwrap();
```
```

--------------------------------

### Write to PCA9535 Register Pair (Alternative)

Source: https://docs.rs/pca9535/latest/src/pca9535/lib.rs.html

Demonstrates writing a half-word to a register pair, specifically `OutputPort1`, and then reading the individual bytes. This highlights the paired nature of the registers.

```rust
use rppal::i2c::I2c;
use pca9535::Pca9535Immediate;
use pca9535::Expander;
use pca9535::Register;

let i2c = I2c::new().unwrap();
let address = 32;

let mut expander = Pca9535Immediate::new(i2c, address);

expander.write_halfword(Register::OutputPort1, 0x4A07 as u16).unwrap();

let mut output_bank0: u8 = 0x00;
let mut output_bank1: u8 = 0x00;

expander.read_byte(Register::OutputPort0, &mut output_bank0).unwrap();
expander.read_byte(Register::OutputPort1, &mut output_bank1).unwrap();

assert_eq!(output_bank0, 0x07 as u8);
assert_eq!(output_bank1, 0x4A as u8);
```

--------------------------------

### StandardExpanderInterface Operations

Source: https://docs.rs/pca9535/latest/index.html

Provides functions to interact with the expander, such as setting pin directions and states.

```APIDOC
## StandardExpanderInterface Operations

### Description
This interface offers various functions to interact with the IO expander. These functions do not maintain state regarding the current configuration of pins as inputs or outputs. The user must ensure that the pins are in the desired configuration before calling other functions to achieve expected results.

### Methods
- `pin_into_output(bank, pin)`: Configures a specific pin as an output.
- `pin_set_high(bank, pin)`: Sets a pin configured as output to a high state.
- `pin_set_low(bank, pin)`: Sets a pin configured as output to a low state.
- `pin_is_high(bank, pin)`: Checks if a pin configured as input is high.
- `pin_is_low(bank, pin)`: Checks if a pin configured as input is low.

### Parameters
- **bank**: The GPIO bank (e.g., `GPIOBank::Bank0`).
- **pin**: The pin number within the bank (0-7).

### Request Example
```rust
use rppal::i2c::I2c;
use pca9535::GPIOBank;
use pca9535::StandardExpanderInterface;
use pca9535::Pca9535Immediate; // Or Pca9535Cached

let i2c = I2c::new().unwrap();
let address = 32;

let mut expander = Pca9535Immediate::new(i2c, address); // Either Immediate or Cached expander

expander.pin_into_output(GPIOBank::Bank0, 3).unwrap();
expander.pin_set_high(GPIOBank::Bank0, 3).unwrap();
// ... and so on for other operations
```
```

--------------------------------

### Write and Read PCA9535 Registers

Source: https://docs.rs/pca9535/latest/src/pca9535/lib.rs.html

Shows how to write a half-word to a register pair and then read individual bytes from those registers. This is useful for direct control over the expander's configuration and state.

```rust
use rppal::i2c::I2c;
use pca9535::Pca9535Immediate;
use pca9535::Expander;
use pca9535::Register;

let i2c = I2c::new().unwrap();
let address = 32;

let mut expander = Pca9535Immediate::new(i2c, address);

expander.write_halfword(Register::OutputPort0, 0x4A07 as u16).unwrap();

let mut output_bank0: u8 = 0x00;
let mut output_bank1: u8 = 0x00;

expander.read_byte(Register::OutputPort0, &mut output_bank0).unwrap();
expander.read_byte(Register::OutputPort1, &mut output_bank1).unwrap();

assert_eq!(output_bank0, 0x4A as u8);
assert_eq!(output_bank1, 0x07 as u8);
```

--------------------------------

### Pca9535Cached Initialization

Source: https://docs.rs/pca9535/latest/index.html

Initializes the PCA9535 expander in cached mode, reducing I2C bus traffic by maintaining internal state.

```APIDOC
## Pca9535Cached Initialization

### Description
Initializes the PCA9535 expander in cached mode. This mode internally stores the state of the device registers to minimize I2C bus traffic. It relies on the open-drain interrupt pin of the device to detect any changes to the registers, making the use of this hardware pin mandatory for this interface.

### Method
`Pca9535Cached::new(i2c, address, interrupt_pin, initialize_cache)`

### Parameters
- **i2c**: An I2C bus instance implementing the `embedded-hal` traits.
- **address**: The 7-bit I2C address of the PCA9535 device.
- **interrupt_pin**: A HAL GPIO Input pin connected to the interrupt pin of the IO Expander.
- **initialize_cache**: A boolean indicating whether to initialize the internal cache to default values.

### Request Example
```rust
use rppal::i2c::I2c;
use rppal::gpio::Gpio;
use pca9535::Pca9535Cached;

let gpio = Gpio::new().unwrap();
// A HAL GPIO Input pin which is connected to the interrupt pin of the IO Expander
let expander_interrupt_pin = gpio.get(0).unwrap().into_input();

let i2c = I2c::new().unwrap();
let address = 32;

let expander = Pca9535Cached::new(i2c, address, expander_interrupt_pin, true); // create cached expander and initialize cache to defaults
```
```

--------------------------------

### Create Pca9535Immediate Instance

Source: https://docs.rs/pca9535/latest/pca9535/expander/immediate/struct.Pca9535Immediate.html

Instantiates a new Pca9535Immediate struct. Panics if the provided I2C device address is outside the valid range of 32-39.

```rust
pub fn new(i2c: I2C, address: u8) -> Self
```

--------------------------------

### SyncExpander for IoExpander

Source: https://docs.rs/pca9535/latest/src/pca9535/expander/io.rs.html

Implementation of the SyncExpander trait for IoExpander, providing thread-safe methods for reading and writing to the expander.

```APIDOC
## SyncExpander for IoExpander

### Description
This implementation allows `IoExpander` to be used in a multi-threaded context by providing thread-safe access to the underlying expander.

### Methods

#### `write_byte`

Writes a single byte to the specified register.

##### Signature
```rust
fn write_byte(&self, register: Register, data: u8) -> Result<(), ExpanderError<<I2C as ErrorType>::Error>>
```

#### `read_byte`

Reads a single byte from the specified register.

##### Signature
```rust
fn read_byte(&self, register: Register, buffer: &mut u8) -> Result<(), ExpanderError<<I2C as ErrorType>::Error>>
```

#### `write_halfword`

Writes a halfword (16 bits) to the specified register.

##### Signature
```rust
fn write_halfword(&self, register: Register, data: u16) -> Result<(), ExpanderError<<I2C as ErrorType>::Error>>
```

#### `read_halfword`

Reads a halfword (16 bits) from the specified register.

##### Signature
```rust
fn read_halfword(&self, register: Register, buffer: &mut u16) -> Result<(), ExpanderError<<I2C as ErrorType>::Error>>
```
```

--------------------------------

### OutputPin Trait Implementations

Source: https://docs.rs/pca9535/latest/pca9535/pin/struct.ExpanderOutputPin.html

The ExpanderOutputPin struct implements the `OutputPin` trait, providing methods to control the state of the output pin.

```APIDOC
## OutputPin Trait Implementations

### Description
Provides methods to control the output pin's state.

### Methods

#### `set_low()`

##### Description
Drives the pin low.

##### Returns
A `Result` indicating success or an error.

#### `set_high()`

##### Description
Drives the pin high.

##### Returns
A `Result` indicating success or an error.

#### `set_state(state)`

##### Description
Drives the pin high or low depending on the provided `PinState`.

##### Parameters
- `state`: The desired `PinState` (high or low).

##### Returns
A `Result` indicating success or an error.
```

--------------------------------

### Pca9535Cached::new

Source: https://docs.rs/pca9535/latest/pca9535/expander/cached/struct.Pca9535Cached.html

Creates a new cached PCA9535 instance. The `init_defaults` argument determines whether to assume default register values or read existing values from the device.

```APIDOC
## pub fn new(
    i2c: I2C,
    address: u8,
    interrupt_pin: IP,
    init_defaults: bool,
) -> Result<Self, ExpanderError<E>>

### Description
Creates a new cached PCA9535 instance.

### Arguments
* `i2c`: The I2C bus interface.
* `address`: The hardware address of the PCA9535 device.
* `interrupt_pin`: The interrupt pin of the PCA9535 device.
* `init_defaults`: If `true`, assumes default values for all device registers. If `false`, reads existing register values from the device.

### Returns
A `Result` containing the new `Pca9535Cached` instance or an `ExpanderError`.

### Panics
If the given device hardware address is outside the permittable range of `32-39`.
```

--------------------------------

### Writing and Reading Half-Words to PCA9535 Registers

Source: https://docs.rs/pca9535/latest/pca9535/enum.Register.html

Demonstrates writing a 16-bit value to a register pair (e.g., OutputPort0 and OutputPort1) and then reading back individual bytes to verify the operation. The least significant byte of the half-word is written to the first register, and the most significant byte to the second.

```rust
expander.write_halfword(Register::OutputPort0, 0x4A07 as u16).unwrap();

let mut output_bank0: u8 = 0x00;
let mut output_bank1: u8 = 0x00;

expander.read_byte(Register::OutputPort0, &mut output_bank0).unwrap();
expander.read_byte(Register::OutputPort1, &mut output_bank1).unwrap();

assert_eq!(output_bank0, 0x4A as u8);
assert_eq!(output_bank1, 0x07 as u8);
```

```rust
expander.write_halfword(Register::OutputPort1, 0x4A07 as u16).unwrap();

let mut output_bank0: u8 = 0x00;
let mut output_bank1: u8 = 0x00;

expander.read_byte(Register::OutputPort0, &mut output_bank0).unwrap();
expander.read_byte(Register::OutputPort1, &mut output_bank1).unwrap();

assert_eq!(output_bank0, 0x07 as u8);
assert_eq!(output_bank1, 0x4A as u8);
```

--------------------------------

### Into Trait Implementation

Source: https://docs.rs/pca9535/latest/pca9535/expander/immediate/struct.Pca9535Immediate.html

Allows converting an instance into another type that implements `From`.

```APIDOC
## impl<T, U> Into<U> for T
where U: From<T>,

### Description
Provides a way to convert a value of type `T` into a value of type `U`, where `U` implements `From<T>`.

### fn into(self) -> U

#### Description
Calls `U::from(self)`.

#### Parameters
- `self`: The value to convert.

#### Returns
- `U`: The converted value.
```

--------------------------------

### StandardExpanderInterface Operations

Source: https://docs.rs/pca9535/latest/pca9535/index.html

Provides standard functions to interact with the PCA9535 expander, regardless of the operation type (Immediate or Cached).

```APIDOC
## StandardExpanderInterface

### Description
This trait provides common functions to interact with the PCA9535 IO expander. Users must ensure correct pin configurations before use.

### Methods
- `pin_into_output(bank, pin)`: Configures a specific pin as an output.
- `pin_set_high(bank, pin)`: Sets a pin configured as output to a high logic level.
- `pin_set_low(bank, pin)`: Sets a pin configured as output to a low logic level.
- `pin_read(bank, pin)`: Reads the current state of a pin.
- `pin_into_input(bank, pin)`: Configures a specific pin as an input.
- `pin_toggle_high(bank, pin)`: Toggles a pin configured as output from low to high.
- `pin_toggle_low(bank, pin)`: Toggles a pin configured as output from high to low.

### Parameters
- `bank`: The GPIO bank (e.g., `GPIOBank::Bank0`).
- `pin`: The pin number within the bank (0-7).

### Request Example
```rust
use rppal::i2c::I2c;
use pca9535::GPIOBank;
use pca9535::StandardExpanderInterface;
use pca9535::Pca9535Immediate;

let i2c = I2c::new().unwrap();
let address = 32;

let mut expander = Pca9535Immediate::new(i2c, address);

expander.pin_into_output(GPIOBank::Bank0, 3).unwrap();
expander.pin_set_high(GPIOBank::Bank0, 3).unwrap();
let pin_state = expander.pin_read(GPIOBank::Bank0, 3).unwrap();
```
```
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