Copyright	(c) 2016, Drew Hess
License	BSD3
Maintainer	Drew Hess <src@drewhess.com>
Stability	experimental
Portability	non-portable
Safe Haskell	Trustworthy
Language	Haskell2010

System.GPIO.Types

Contents

GPIO pins
Convenience functions
PinValue conversion to/from Bool
GPIO exceptions

Description

Basic GPIO types.

Synopsis

GPIO pins

newtype Pin Source

A GPIO pin, identified by pin number.

Note that GPIO pin numbering is platform- and runtime-dependent. See the documentation for your particular platform for an explanation of how pin numbers are assigned to physical pins.

Constructors

Pin Int

Instances

Bounded Pin Source
Enum Pin Source
Eq Pin Source
Data Pin Source
Ord Pin Source
Read Pin Source
Show Pin Source
Ix Pin Source
Generic Pin Source
Arbitrary Pin Source
type Rep Pin Source

data PinInputMode Source

GPIO pins may support a number of different physical configurations when used as a digital input.

Pins that are capable of input will at least support the InputDefault mode. InputDefault mode is special in that, unlike the other input modes, it does not represent a unique physical configuration, but is simply a pseudonym for another (actual) input mode. Exactly which mode is used by the hardware when InputDefault mode is specified is platform-dependent. By using InputDefaut mode, you are saying that you don't care about the pin's actual configuration, other than the fact that it's being used for input.

Constructors

InputDefault	The pin's default input mode, i.e., the mode used when a more specific mode is not specified
InputFloating	A floating / high-impedance / tri-state mode which uses little power, but when disconnected, may cause the pin's value to be indeterminate
InputPullUp	The pin is connected to an internal pull-up resistor such that, when the pin is disconnected or connected to a floating / high-impedance node, its physical value will be `High`
InputPullDown	The pin is connected to an internal pull-down resistor such that, when the pin is disconnected or connected to a floating / high-impedance node, its physical value will be `Low`

data PinOutputMode Source

GPIO pins may support a number of different physical configurations when used as a digital output.

Pins that are capable of output will at least support the OutputDefault mode. OutputDefault mode is special in that, unlike the other output modes, it does not represent a unique physical configuration, but is simply a pseudonym for another (actual) output mode. Exactly which mode is used by the hardware when OutputDefault mode is specified is platform-dependent. By using OutputDefaut mode, you are saying that you don't care about the pin's actual configuration, other than the fact that it's being used for output.

Constructors

OutputDefault	The pin's default output mode, i.e., the mode used when a more specific mode is not specified
OutputPushPull	The output actively drives both the `High` and `Low` states
OutputOpenDrain	The output actively drives the `Low` state, but `High` is left floating (also known as open collector)
OutputOpenDrainPullUp	The output actively drives the `Low` state, and is connected to an internal pull-up resistor in the `High` state.
OutputOpenSource	The output actively drives the `High` state, but `Low` is left floating (also known as open emitter)
OutputOpenSourcePullDown	The output actively drives the `High` state, and is connected to an internal pull-down resistor in the `Low` state.

data PinCapabilities Source

Catalog a pin's capabilities.

Constructors

PinCapabilities
Fields _inputModes :: Set PinInputMode The set of input modes that the pin supports _outputModes :: Set PinOutputMode The set of output modes that the pin supports _interrupts :: Bool Does the pin support interrupts in input mode?

Instances

Eq PinCapabilities Source
Show PinCapabilities Source
Generic PinCapabilities Source
type Rep PinCapabilities Source

data PinDirection Source

A pin's direction (input/output).

Constructors

In
Out

data PinActiveLevel Source

A pin's active level (active-high/active-low).

Constructors

ActiveLow
ActiveHigh

data PinValue Source

A pin's signal level as a binary value.

Constructors

Low
High

data PinInterruptMode Source

A pin's interrupt mode.

Note that the pin's interrupt mode is defined in terms of the pin's logical signal value; i.e., when the pin is configured for active-low logic, RisingEdge refers to the physical signal's trailing edge, and FallingEdge refers to the physical signal's rising edge.

Constructors

Disabled	Interrupts are disabled
RisingEdge	Interrupt on the pin's (logical) rising edge
FallingEdge	Interrupt on the pin's (logical) falling edge
Level	Interrupt on any change to the pin's signal level

Convenience functions

pinNumber :: Pin -> Int Source

Get the pin number as an Int.

>>> pinNumber (Pin 5)
5

invertDirection :: PinDirection -> PinDirection Source

Invert a PinDirection value.

>>> invertDirection In
Out
>>> invertDirection Out
In

invertValue :: PinValue -> PinValue Source

Invert a PinValue.

>>> invertValue High
Low
>>> invertValue Low
High

PinValue conversion to/from Bool

valueToBool :: PinValue -> Bool Source

Convert a PinValue to its logical boolean equivalent.

>>> valueToBool High
True
>>> valueToBool Low
False

boolToValue :: Bool -> PinValue Source

Convert a Bool to its logical PinValue equivalent.

>>> boolToValue True
High
>>> boolToValue False
Low

GPIO exceptions

data SomeGpioException Source

The top level of the GPIO exception hierarchy.

Constructors

forall e . Exception e => SomeGpioException e

Instances

Show SomeGpioException Source
Exception SomeGpioException Source

gpioExceptionToException :: Exception e => e -> SomeException Source

Convert SomeGpioException to SomeException.

gpioExceptionFromException :: Exception e => SomeException -> Maybe e Source

Ask whether an exception is SomeGpioException.

Bounded PinInputMode Source
Enum PinInputMode Source
Eq PinInputMode Source
Data PinInputMode Source
Ord PinInputMode Source
Read PinInputMode Source
Show PinInputMode Source
Generic PinInputMode Source
type Rep PinInputMode Source

Bounded PinOutputMode Source
Enum PinOutputMode Source
Eq PinOutputMode Source
Data PinOutputMode Source
Ord PinOutputMode Source
Read PinOutputMode Source
Show PinOutputMode Source
Generic PinOutputMode Source
type Rep PinOutputMode Source

Bounded PinDirection Source
Enum PinDirection Source
Eq PinDirection Source
Data PinDirection Source
Ord PinDirection Source
Read PinDirection Source
Show PinDirection Source
Ix PinDirection Source
Generic PinDirection Source
Arbitrary PinDirection Source
type Rep PinDirection Source

Bounded PinActiveLevel Source
Enum PinActiveLevel Source
Eq PinActiveLevel Source
Data PinActiveLevel Source
Ord PinActiveLevel Source
Read PinActiveLevel Source
Show PinActiveLevel Source
Ix PinActiveLevel Source
Generic PinActiveLevel Source
Arbitrary PinActiveLevel Source
type Rep PinActiveLevel Source

Bounded PinValue Source
Enum PinValue Source
Eq PinValue Source
Data PinValue Source
Ord PinValue Source
Read PinValue Source
Show PinValue Source
Ix PinValue Source
Generic PinValue Source
Arbitrary PinValue Source
Bits PinValue Source
FiniteBits PinValue Source
type Rep PinValue Source

Bounded PinInterruptMode Source
Enum PinInterruptMode Source
Eq PinInterruptMode Source
Data PinInterruptMode Source
Ord PinInterruptMode Source
Read PinInterruptMode Source
Show PinInterruptMode Source
Generic PinInterruptMode Source
Arbitrary PinInterruptMode Source
type Rep PinInterruptMode Source