PCA9535

https://docs.rs/pca9535/2.0.0/
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PCA9535 is a Rust driver library for 16-bit IO-Expanders using I2C/SMBus interface with support for...
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### Configure Pin as Output and Set High

Source: https://docs.rs/pca9535/2.0.0/pca9535

Demonstrates using the `StandardExpanderInterface` to configure a specific pin as an output and then set its state to high. Ensure the pin is correctly configured 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 Type ID

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/immediate/struct.Pca9535Immediate.html

Returns the `TypeId` of the current type. This is part of the `Any` trait implementation.

```rust
fn type_id(&self) -> TypeId>
```

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

### Get Cached Register Value

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/expander/cached.rs.html

Retrieves the cached value for a specified PCA9535 register. This method avoids I2C transactions by returning the value stored in the struct's fields.

```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,
        }
    }
```

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

### Module: immediate

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/index.html

Contains the implementation of the Immediate Expander interface.

```APIDOC
## Module immediate

### Description
Contains the implementation of the Immediate Expander interface.
```

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

### ExpanderOutputPin::new

Source: https://docs.rs/pca9535/2.0.0/pca9535/pin/struct.ExpanderOutputPin.html

Creates a new `ExpanderOutputPin` instance.

```APIDOC
## Function ExpanderOutputPin::new

### Description
Create a new output pin.

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

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

#### Arguments
* `expander` (&'a Io): A reference to the `SyncExpander` instance.
* `bank` (GPIOBank): The GPIO bank the pin belongs to (e.g., 0 or 1).
* `pin` (u8): The pin number within the bank (0-7).
* `state` (PinState): The initial state of the pin (e.g., `PinState::High` or `PinState::Low`).

### Returns
A `Result` containing the new `ExpanderOutputPin` instance on success, or an `ExpanderError` on failure.

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

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

### Module: io

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/index.html

Contains the implementation to make an `Expander` Sync.

```APIDOC
## Module io

### Description
Contains the implementation to make an `Expander` Sync.
```

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

### Create Immediate PCA9535 Instance

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/expander/immediate.rs.html

Initializes a new PCA9535 immediate expander instance. 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 }
    }
```

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

### Initialize IO Expander with Mutex Wrapper

Source: https://docs.rs/pca9535/2.0.0/pca9535

Initializes an I2C connection and wraps a PCA9535 expander in an `IoExpander` with a `Mutex` for thread-safe access in a standard environment. Ensure the 'std' feature is enabled for this implementation.

```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
```

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

### Create and Use Expander HAL Pins

Source: https://docs.rs/pca9535/2.0.0/pca9535

Demonstrates creating input and output pins from a wrapped IO expander. Requires the 'std' feature to be enabled. Pins implement standard HAL traits for GPIO manipulation.

```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...
```

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

### IoExpander::new

Source: https://docs.rs/pca9535/2.0.0/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.

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

### Parameters
- **expander** (Ex): The Expander instance to wrap.

### Returns
- IoExpander<I2C, Ex, Em>: A new IoExpander instance.

### Example
```rust
// let expander: SomeExpanderType = ...;
// let io_expander = IoExpander::<_ , _ , _>::new(expander);
```
```

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

### ExpanderInputPin Methods

Source: https://docs.rs/pca9535/2.0.0/pca9535/pin/struct.ExpanderInputPin.html

Methods available for creating and configuring an ExpanderInputPin.

```APIDOC
## impl<'a, I2C, E, Io> ExpanderInputPin<'a, I2C, Io>

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

#### Description
Create a new input pin.

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

### pub fn set_polarity(&mut self, polarity: Polarity) -> Result<(), ExpanderError<E>>

#### Description
Sets the polarity of the input pin. The input pins have normal polarity by default on device startup.
If the polarity is `Polarity::Normal` a logic `high` voltage level on the input is detected as `high` in the software.
If the polarity is `Polarity::Inverse` a logic `high` voltage level on the input is detected as `low` by the software.
```

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

### Configure Pin as Output

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/immediate/struct.Pca9535Immediate.html

Configures a specified GPIO pin to operate as an output.

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

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

### Create New Pca9535Cached Instance

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/cached/struct.Pca9535Cached.html

Initializes a new Pca9535Cached instance. Set `init_defaults` to true if no prior transactions have been made with the device to assume default register values. Otherwise, set to false to read existing register states.

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

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

### Create New PCA9535Cached Instance

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/expander/cached.rs.html

Constructs a new PCA9535Cached instance. The `init_defaults` flag determines whether to initialize the cache by reading device registers or assume default values. Panics if the address is out of range.

```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)
    }
```

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

### Configure Pin as Input

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/immediate/struct.Pca9535Immediate.html

Configures a specified GPIO pin to operate as an input.

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

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

### Create PCA9535 Input Pin

Source: https://docs.rs/pca9535/2.0.0/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,
        })
    }
```

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

### Pin Configuration and State

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/cached/struct.Pca9535Cached.html

APIs for configuring pin direction, checking pin state, and setting polarity.

```APIDOC
## POST /websites/rs_pca9535_2_0_0/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.

### Method
POST

### Endpoint
/websites/rs_pca9535_2_0_0/pin_is_low

### Parameters
#### Path Parameters
- **bank** (GPIOBank) - Required - The GPIO bank to operate on.
- **pin** (u8) - Required - The pin number.

### Request Body
```json
{
  "bank": "A",
  "pin": 0
}
```

### Response
#### Success Response (200)
- **result** (bool) - True if the pin is low, false otherwise.

#### Response Example
```json
{
  "result": true
}
```
```

```APIDOC
## POST /websites/rs_pca9535_2_0_0/pin_into_input

### Description
Configures the given pin as input.

### Method
POST

### Endpoint
/websites/rs_pca9535_2_0_0/pin_into_input

### Parameters
#### Path Parameters
- **bank** (GPIOBank) - Required - The GPIO bank to operate on.
- **pin** (u8) - Required - The pin number.

### Request Body
```json
{
  "bank": "A",
  "pin": 0
}
```

### Response
#### Success Response (200)
- **result** (string) - Indicates success or failure.

#### Response Example
```json
{
  "result": "success"
}
```
```

```APIDOC
## POST /websites/rs_pca9535_2_0_0/pin_into_output

### Description
Configures the given pin as output.

### Method
POST

### Endpoint
/websites/rs_pca9535_2_0_0/pin_into_output

### Parameters
#### Path Parameters
- **bank** (GPIOBank) - Required - The GPIO bank to operate on.
- **pin** (u8) - Required - The pin number.

### Request Body
```json
{
  "bank": "A",
  "pin": 0
}
```

### Response
#### Success Response (200)
- **result** (string) - Indicates success or failure.

#### Response Example
```json
{
  "result": "success"
}
```
```

```APIDOC
## POST /websites/rs_pca9535_2_0_0/pin_inverse_polarity

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

### Method
POST

### Endpoint
/websites/rs_pca9535_2_0_0/pin_inverse_polarity

### Parameters
#### Path Parameters
- **bank** (GPIOBank) - Required - The GPIO bank to operate on.
- **pin** (u8) - Required - The pin number.

### Request Body
```json
{
  "bank": "A",
  "pin": 0
}
```

### Response
#### Success Response (200)
- **result** (string) - Indicates success or failure.

#### Response Example
```json
{
  "result": "success"
}
```
```

```APIDOC
## POST /websites/rs_pca9535_2_0_0/pin_normal_polarity

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

### Method
POST

### Endpoint
/websites/rs_pca9535_2_0_0/pin_normal_polarity

### Parameters
#### Path Parameters
- **bank** (GPIOBank) - Required - The GPIO bank to operate on.
- **pin** (u8) - Required - The pin number.

### Request Body
```json
{
  "bank": "A",
  "pin": 0
}
```

### Response
#### Success Response (200)
- **result** (string) - Indicates success or failure.

#### Response Example
```json
{
  "result": "success"
}
```
```

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

### PinState Blanket Implementations

Source: https://docs.rs/pca9535/2.0.0/pca9535/enum.PinState.html

Details blanket implementations for PinState, covering traits like Any, Borrow, BorrowMut, CloneToUninit, From<T>, Into<U>, and TryFrom<U>/TryInto<U>.

```APIDOC
## Blanket Implementations

### impl<T> Any for T

#### fn type_id(&self) -> TypeId
Gets the `TypeId` of `self`.

### impl<T> Borrow<T> for T

#### fn borrow(&self) -> &T
Immutably borrows from an owned value.

### impl<T> BorrowMut<T> for T

#### fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value.

### impl<T> CloneToUninit for T

#### unsafe fn clone_to_uninit(&self, dest: *mut u8)
Performs copy-assignment from `self` to `dest`.

### impl<T> From<T> for T

#### fn from(t: T) -> T
Returns the argument unchanged.

### impl<T, U> Into<U> for T

#### fn into(self) -> U
Calls `U::from(self)`.

### impl<T, U> TryFrom<U> for T

#### type Error = Infallible

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
Performs the conversion.

### impl<T, U> TryInto<U> for T

#### type Error = <U as TryFrom<T>>::Error

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
Performs the conversion.
```

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

### Register Helper Methods

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/lib.rs.html

Methods to identify register types for input and polarity inversion.

```rust
    /// Returns true if register is an input register
    fn is_input(&self) -> bool {
        matches!(self, Self::InputPort0 | Self::InputPort1)
    }

    /// Returns true if register is a polarity inversion register
    fn is_polarity_inversion(&self) -> bool {
        matches!(
            self,
            Self::PolarityInversionPort0 | Self::PolarityInversionPort1
        )
    }
```

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

### Write Halfword to Output Port 1 and Read

Source: https://docs.rs/pca9535/2.0.0/pca9535/enum.Register.html

Illustrates writing a halfword to the second output port register and subsequently reading byte values from both output port registers. This shows how writing to one register of a pair impacts the other.

```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);
```

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

### Implement OutputPin for ExpanderOutputPin

Source: https://docs.rs/pca9535/2.0.0/pca9535/pin/struct.ExpanderOutputPin.html

Provides implementations for driving the pin low, high, or setting its state based on a PinState enum. These methods return a Result indicating success or an ExpanderError.

```rust
fn set_low(&mut self) -> Result<(), Self::Error>

```

```rust
fn set_high(&mut self) -> Result<(), Self::Error>

```

```rust
fn set_state(&mut self, state: PinState) -> Result<(), Self::Error>

```

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

### Create ExpanderOutputPin

Source: https://docs.rs/pca9535/2.0.0/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>>

```

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

### Generic `CloneToUninit::clone_to_uninit`

Source: https://docs.rs/pca9535/2.0.0/pca9535/enum.PinState.html

Nightly-only experimental implementation of `CloneToUninit::clone_to_uninit` for generic types `T` that implement `Clone`. This performs copy-assignment to an uninitialized memory location.

```rust
unsafe fn clone_to_uninit(&self, dest: *mut u8)
```

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

### Create New Pca9535Immediate Instance

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/immediate/struct.Pca9535Immediate.html

Initializes a new Pca9535Immediate instance. Panics if the provided I2C address is out of the valid range (32-39).

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

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

### Create PCA9535 Output Pin

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/pin.rs.html

Initializes a new output pin for the PCA9535 expander with a specified initial state. 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,
        })
    }
```

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

### Create ExpanderInputPin

Source: https://docs.rs/pca9535/2.0.0/pca9535/pin/struct.ExpanderInputPin.html

Creates a new input pin instance. Panics if the pin number is outside the valid range of 0-7. Requires a reference to the expander, the bank, and the pin number.

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

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

### StandardExpanderInterface Methods

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/standard/trait.StandardExpanderInterface.html

This section details the methods available in the StandardExpanderInterface trait for interacting with the PCA9535 expander.

```APIDOC
## StandardExpanderInterface

### Description
Standard expander interface not using `hal`. This interface does not track the state of the pins! Therefore, the user needs to ensure the pins are in input or output configuration before proceeding to call functions related to input or output pins. Otherwise, the results of those functions might not cause the expected behavior of the device.

### Methods

#### `pin_set_high(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`
Sets the specified pin to a high state.

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

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

#### `pin_is_high(&mut self, bank: GPIOBank, pin: u8) -> Result<bool, ExpanderError<E>>`
Checks if the input state of the given pin is `high`. This function works with pins configured as inputs as well as outputs.
The function result does not necessarily represent the logic level of the applied voltage at the given pin but the value inside the input register of the device. Which is `1` or `0` Depending on the current polarity inversion configuration of the pin.

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

#### `pin_is_low(&mut self, bank: GPIOBank, pin: u8) -> Result<bool, ExpanderError<E>>`
Checks if the input state of the given pin is `low`. This function works with pins configured as inputs as well as outputs.
The function result does not necessarily represent the logic level of the applied voltage at the given pin but the value inside the input register of the device. Which is `1` or `0` Depending on the current polarity inversion configuration of the pin.

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

#### `pin_into_input(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`
Configures the specified pin as input.

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

#### `pin_into_output(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`
Configures the specified pin as output.

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

#### `pin_inverse_polarity(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`
Sets the input polarity of the specified pin to inverted. A logic high voltage applied at this input pin results in a `0` written to the device's input register and thus being registered as `low` by the driver.

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

#### `pin_normal_polarity(&mut self, bank: GPIOBank, pin: u8) -> Result<(), ExpanderError<E>>`
Sets the input polarity of the specified pin to normal. A logic high voltage applied at an input pin results in a `1` written to the device's input register, thus being registered as `high` by the driver.

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

#### `inverse_polarity(&mut self) -> Result<(), ExpanderError<E>>`
Sets the input polarity of all pins to inverted. A logic high voltage applied at an input pin results in a `0` written to the device's input register, thus being registered as `low` by the driver.

#### `normal_polarity(&mut self) -> Result<(), ExpanderError<E>>`
Sets the input polarity of all pins to normal. A logic high voltage applied at an input pin results in a `1` written to the device's input register, thus being registered as `high` by the driver.
```

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

### Module: standard

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/index.html

Implements the standard interface for all types implementing the `Expander` trait.

```APIDOC
## Module standard

### Description
Implements the standard interface for all types implementing the `Expander` trait.
```

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

### Initialize Cache for PCA9535

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/expander/cached.rs.html

Reads all necessary device registers (Configuration, Input, Output, Polarity Inversion) from the PCA9535 and populates the internal cache. Handles potential I2C write-read errors.

```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(())
    }
```

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

### From Trait Implementation

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/immediate/struct.Pca9535Immediate.html

Allows creating an instance of a type from another type.

```APIDOC
## POST /websites/rs_pca9535_2_0_0/from

### Description
Creates an instance of a type from another type. This implementation returns the argument unchanged.

### Method
POST

### Endpoint
/websites/rs_pca9535_2_0_0/from

### Parameters
#### Request Body
- **t** (T) - Required - The value to convert from.

### Response
#### Success Response (200)
- **T** (T) - The created instance, which is the same as the input value.
```

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

### Write and Read Halfword to Output Ports

Source: https://docs.rs/pca9535/2.0.0/pca9535/enum.Register.html

Demonstrates writing a halfword to one output port register and then reading individual byte values from both output port registers. Note that writing to one register of a pair affects the other.

```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);
```

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

### Configure Pin as Output - PCA9535 Expander

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/expander/standard.rs.html

Configures a specified pin as an output. This modifies the device's configuration register. Panics if the pin number 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,

```

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

### Initialize Immediate PCA9535 Expander

Source: https://docs.rs/pca9535/2.0.0/pca9535

Instantiates the `Pca9535Immediate` expander. This interface issues an I2C transaction on each function call and does not use the interrupt pin.

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

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

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

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

### Implement Copy for GPIOBank

Source: https://docs.rs/pca9535/2.0.0/pca9535/enum.GPIOBank.html

Indicates that GPIOBank can be copied implicitly. This is suitable for simple enums where values are cheap to copy.

```rust
impl Copy for GPIOBank
```

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

### PCA9535 Immediate Expander API

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/expander/immediate.rs.html

This section details the PCA9535 immediate expander interface, which allows for direct interaction with the device's registers.

```APIDOC
## Pca9535Immediate<I2C>

### Description
Represents an immediate PCA9535 expander instance, providing direct register access.

### Methods

#### `new(i2c: I2C, address: u8) -> Self`

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 in the range of 32-39.

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

#### `destroy(self) -> I2C`

Destroys the expander struct, returning the contained I2C peripheral.

### Trait Implementations

#### `Expander<I2C>`

##### `write_byte(&mut self, register: Register, data: u8) -> Result<(), ExpanderError<E>>`

Writes one byte to the given register. Use with caution, as simpler methods are usually available.

**Parameters:**
- `register` (Register): The target register.
- `data` (u8): The byte data to write.

**Returns:**
`Ok(())` on success, or `Err(ExpanderError::WriteError)` on failure.

##### `read_byte(&mut self, register: Register, buffer: &mut u8) -> Result<(), ExpanderError<E>>`

Reads one byte from the given register. Use with caution, as simpler methods are usually available.

**Parameters:**
- `register` (Register): The register to read from.
- `buffer` (&mut u8): A mutable reference to store the read byte.

**Returns:**
`Ok(())` on success, or `Err(ExpanderError::WriteReadError)` on failure.

##### `write_halfword(&mut self, register: Register, data: u16) -> Result<(), ExpanderError<E>>`

Writes one halfword (16 bits) to the given register. Use with caution, as simpler methods are usually available.

**Parameters:**
- `register` (Register): The target register. Note: Register pairs might affect behavior.
- `data` (u16): The halfword data to write.

**Returns:**
`Ok(())` on success, or `Err(ExpanderError::WriteError)` on failure.

##### `read_halfword(&mut self, register: Register, buffer: &mut u16) -> Result<(), ExpanderError<E>>`

Reads one halfword (16 bits) from the given register. Use with caution, as simpler methods are usually available.

**Parameters:**
- `register` (Register): The register to read from. Note: Register pairs might affect behavior.
- `buffer` (&mut u16): A mutable reference to store the read halfword.

**Returns:**
`Ok(())` on success, or `Err(ExpanderError::WriteReadError)` on failure.

#### `StandardExpanderInterface<I2C, E>`

This trait is implemented but has no specific methods documented here, implying it reuses or extends functionality from the `Expander` trait.
```

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

### Pca9535Cached::new

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/cached/struct.Pca9535Cached.html

Creates a new cached PCA9535 instance. Handles initialization of device registers based on the `init_defaults` flag.

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

### Description
Creates a new cached PCA9535 instance.

### Parameters

* `i2c`: The I2C peripheral to use for communication.
* `address`: The I2C address of the PCA9535 device.
* `interrupt_pin`: The interrupt pin connected to the PCA9535.
* `init_defaults`: If `true`, assumes default register values and avoids initial bus transaction. If `false`, reads all registers to cache their current state.

### 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`.
```

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

### Configure Pin as Input - PCA9535 Expander

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/expander/standard.rs.html

Configures a specified pin as an input. This modifies the device's configuration register. Panics if the pin number 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))
    }
```

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

### OutputPin Trait Implementation for ExpanderOutputPin

Source: https://docs.rs/pca9535/2.0.0/pca9535/pin/struct.ExpanderOutputPin.html

Provides methods to control the state of the output pin.

```APIDOC
## Trait Implementation: OutputPin for ExpanderOutputPin

### Description
This implementation allows the `ExpanderOutputPin` to be used with standard hardware abstraction layer (HAL) components that expect an `OutputPin`.

### Methods

#### `set_low()`

##### Description
Drives the pin low.

##### Method Signature
`fn set_low(&mut self) -> Result<(), Self::Error>`

#### `set_high()`

##### Description
Drives the pin high.

##### Method Signature
`fn set_high(&mut self) -> Result<(), Self::Error>`

#### `set_state(state: PinState)`

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

##### Method Signature
`fn set_state(&mut self, state: PinState) -> Result<(), Self::Error>`

### Error Type
`type Error = ExpanderError<E>` where `E` is the error type associated with the underlying I2C communication.
```

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

### Pca9535Immediate::new

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/immediate/struct.Pca9535Immediate.html

Creates a new PCA9535Immediate instance. Panics if the address is out of the valid range.

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

### Description

Creates a new immediate PCA9535 instance.

### Panics

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

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

### Register Configuration and States

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/lib.rs.html

This section details the possible register configurations, input states, and polarity inversion states for the PCA9535 device.

```APIDOC
## Register Mapping and States

### Description
This section describes the mapping of register states and the logic for determining input and polarity inversion registers.

### Register States

- **PolarityInversionPort0** maps to **PolarityInversionPort1**
- **PolarityInversionPort1** maps to **PolarityInversionPort0**
- **ConfigurationPort0** maps to **ConfigurationPort1**
- **ConfigurationPort1** maps to **ConfigurationPort0**

### Methods

- **is_input()**: Returns `true` if the register is an input register (InputPort0 or InputPort1).
- **is_polarity_inversion()**: Returns `true` if the register is a polarity inversion register (PolarityInversionPort0 or PolarityInversionPort1).

### Enums

#### `GPIOBank`
Represents the GPIO banks of the device.
- `Bank0` (value: 0)
- `Bank1` (value: 1)

#### `Polarity`
Represents the possible polarity states of inputs and outputs.
- `Normal` (value: 0)
- `Inverse` (value: 1)
```

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

### PinState::clone_from

Source: https://docs.rs/pca9535/2.0.0/pca9535/enum.PinState.html

Implementation of `clone_from` for `PinState`, enabling efficient copy-assignment.

```rust
fn clone_from(&mut self, source: &Self)
```

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

### Read Input Pin State (Low)

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/pin.rs.html

Checks if an input pin on the expander is currently set to a low state. Requires the pin and bank to be configured.

```rust
fn is_low(&mut self) -> Result<bool, Self::Error> {
        let register = match self.bank {
            GPIOBank::Bank0 => Register::InputPort0,
            GPIOBank::Bank1 => Register::InputPort1,
        };

        let mut reg_val: u8 = 0x00;

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

        match (reg_val >> self.pin) & 1 {
            1 => Ok(false),
            _ => Ok(true),
        }
    }
```

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

### Pca9535Immediate Struct

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/immediate/struct.Pca9535Immediate.html

Represents an immediate mode PCA9535 I/O expander instance. It requires an I2C peripheral and a device address.

```APIDOC
## Struct Pca9535Immediate

```rust
pub struct Pca9535Immediate<I2C>
where
    I2C: I2c,
{
    /* private fields */
}
```

### Description

Represents an immediate mode PCA9535 I/O expander instance. It requires an I2C peripheral and a device address.
```

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

### Input Pin Reading

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/pin.rs.html

Provides methods to read the current state of input pins on the PCA9535 I/O expander.

```APIDOC
## Input Pin Reading for ExpanderOutputPin

### Description
This section details the methods for reading the state of input pins using the `ExpanderOutputPin` struct, which interacts with the PCA9535 I/O expander.

### Method
- `is_high()`: Reads the state of the specified input pin and returns `true` if it is high.
- `is_low()`: Reads the state of the specified input pin and returns `true` if it is low.

### Endpoint
N/A (This is a library implementation, not a direct API endpoint)

### Parameters
- `self` (ExpanderOutputPin): A mutable reference to the `ExpanderOutputPin` instance.

### Request Body
N/A

### Response
#### Success Response (200)
- `Ok(bool)`: Returns `true` if the pin is high (for `is_high`) or `false` if the pin is high (for `is_low`), and vice-versa.

#### Error Response
- `Err(ExpanderError<E>)`: Indicates an error occurred during the I2C communication or pin reading, where `E` is the underlying I2C error type.

### Request Example
```rust
// Assuming `pin` is an instance of ExpanderOutputPin configured as input
if pin.is_high().expect("Failed to read pin state") {
    println!("Pin is high");
} else {
    println!("Pin is low");
}
```

### Response Example
```rust
// Pin is high:
Ok(true)

// Pin is low:
Ok(false)

// Error:
Err(ExpanderError::IoExpanderError(I2cError::BusError))
```
```

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

### Initialize Cached PCA9535 Expander

Source: https://docs.rs/pca9535/2.0.0/pca9535

Instantiates the `Pca9535Cached` expander. This interface minimizes I2C traffic by maintaining an internal state cache and requires the interrupt pin to be connected.

```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
```

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

### ExpanderInputPin Trait Implementations

Source: https://docs.rs/pca9535/2.0.0/pca9535/pin/struct.ExpanderInputPin.html

Trait implementations for ExpanderInputPin, including Debug, ErrorType, and InputPin.

```APIDOC
## Trait Implementations

### impl<'a, I2C, Io> Debug for ExpanderInputPin<'a, I2C, Io>

#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

### impl<'a, I2C, E, Io> ErrorType for ExpanderInputPin<'a, I2C, Io>

#### type Error = ExpanderError<E>

Error type.

### impl<'a, I2C, E, Io> InputPin for ExpanderInputPin<'a, I2C, Io>

#### 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 Trait Implementations

Source: https://docs.rs/pca9535/2.0.0/pca9535/expander/immediate/struct.Pca9535Immediate.html

Provides a higher-level interface for controlling GPIO pins, including setting direction, state, and polarity.

```APIDOC
### impl<I2C, E> StandardExpanderInterface<I2C, E> for Pca9535Immediate<I2C>

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

Sets the specified pin to a high logic level.

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

Drives the specified pin low.

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

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

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

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

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

Configures the specified pin as an input.

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

Configures the specified pin as an output.

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

Sets the input polarity of the specified pin to inverted.

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

Sets the input polarity of the specified pin to normal.

#### fn inverse_polarity(&mut self) -> Result<(), ExpanderError<E>>

Sets the input polarity of all pins to inverted.

#### fn normal_polarity(&mut self) -> Result<(), ExpanderError<E>>

Sets the input polarity of all pins to normal.
```

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

### Polarity Configuration Methods

Source: https://docs.rs/pca9535/2.0.0/src/pca9535/expander/standard.rs.html

Methods to set input polarity for specific pins or all pins on the PCA9535 device.

```APIDOC
## pin_inverse_polarity

### Description
Sets the input polarity of the given pin to inverted. A logic high voltage applied at this input pin results in a 0 written to the devices input register.

### Parameters
- **bank** (GPIOBank) - Required - The GPIO bank (Bank0 or Bank1).
- **pin** (u8) - Required - The pin index (0-7).

## pin_normal_polarity

### Description
Sets the input polarity of the given pin to normal. A logic high voltage applied at an input pin results in a 1 written to the device's input register.

### Parameters
- **bank** (GPIOBank) - Required - The GPIO bank (Bank0 or Bank1).
- **pin** (u8) - Required - The pin index (0-7).

## inverse_polarity

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

## normal_polarity

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

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

### PinState Auto Trait Implementations

Source: https://docs.rs/pca9535/2.0.0/pca9535/enum.PinState.html

Lists the auto trait implementations for PinState, including Freeze, RefUnwindSafe, Send, Sync, Unpin, and UnwindSafe.

```APIDOC
## Auto Trait Implementations

### impl Freeze for PinState

### impl RefUnwindSafe for PinState

### impl Send for PinState

### impl Sync for PinState

### impl Unpin for PinState

### impl UnwindSafe for PinState
```
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