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//! # Type-erased, value-level module for GPIO pins
//!
//! Although the type-level API is generally preferred, it is not suitable in
//! all cases. Because each pin is represented by a distinct type, it is not
//! possible to store multiple pins in a homogeneous data structure. The
//! value-level API solves this problem by erasing the type information and
//! tracking the pin at run-time.
//!
//! Value-level pins are represented by the [`DynPin`] type. [`DynPin`] has two
//! fields, `id` and `mode` with types [`DynPinId`] and [`DynPinMode`]
//! respectively. The implementation of these types closely mirrors the
//! type-level API.
//!
//! Instances of [`DynPin`] cannot be created directly. Rather, they must be
//! created from their type-level equivalents using [`From`]/[`Into`].
//!
//! ```
//! // Move a pin out of the Pins struct and convert to a DynPin
//! let pa27: DynPin = pins.pa27.into();
//! ```
//!
//! Conversions between pin modes use a value-level version of the type-level
//! API.
//!
//! ```
//! // Use one of the literal function names
//! pa27.into_floating_input();
//! // Use a method and a DynPinMode variant
//! pa27.into_mode(DYN_FLOATING_INPUT);
//! ```
//!
//! Because the pin state cannot be tracked at compile-time, many [`DynPin`]
//! operations become fallible. Run-time checks are inserted to ensure that
//! users don't try to, for example, set the output level of an input pin.
//!
//! Users may try to convert value-level pins back to their type-level
//! equivalents. However, this option is fallible, because the compiler cannot
//! guarantee the pin has the correct ID or is in the correct mode at
//! compile-time. Use [`TryFrom`](core::convert::TryFrom)/
//! [`TryInto`](core::convert::TryInto) for this conversion.
//!
//! ```
//! // Convert to a `DynPin`
//! let pa27: DynPin = pins.pa27.into();
//! // Change pin mode
//! pa27.into_floating_input();
//! // Convert back to a `Pin`
//! let pa27: Pin<PA27, FloatingInput> = pa27.try_into().unwrap();
//! ```
//!
//! # Embedded HAL traits
//!
//! This module implements all of the embedded HAL GPIO traits for [`DynPin`].
//! However, whereas the type-level API uses
//! `Error = core::convert::Infallible`, the value-level API can return a real
//! error. If the [`DynPin`] is not in the correct [`DynPinMode`] for the
//! operation, the trait functions will return
//! [`InvalidPinType`](Error::InvalidPinType).
use core::convert::TryFrom;
use paste::paste;
use crate::ehal::digital::v2::OutputPin;
#[cfg(feature = "unproven")]
use crate::ehal::digital::v2::{InputPin, StatefulOutputPin, ToggleableOutputPin};
use super::pin::*;
use super::reg::RegisterInterface;
//==============================================================================
// DynPinMode configurations
//==============================================================================
/// Value-level `enum` for disabled configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynDisabled {
Floating,
PullDown,
PullUp,
}
/// Value-level `enum` for input configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynInput {
Floating,
PullDown,
PullUp,
}
/// Value-level `enum` for interrupt configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynInterrupt {
Floating,
PullDown,
PullUp,
}
/// Value-level `enum` for output configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynOutput {
PushPull,
Readable,
}
/// Value-level `enum` for alternate peripheral function configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynAlternate {
B,
C,
D,
E,
F,
G,
#[cfg(any(feature = "samd21", feature = "min-samd51g"))]
H,
#[cfg(feature = "min-samd51g")]
I,
#[cfg(feature = "min-samd51g")]
J,
#[cfg(feature = "min-samd51g")]
K,
#[cfg(feature = "min-samd51g")]
L,
#[cfg(feature = "min-samd51g")]
M,
#[cfg(feature = "min-samd51g")]
N,
}
//==============================================================================
// DynPinMode
//==============================================================================
/// Value-level `enum` representing pin modes
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynPinMode {
Disabled(DynDisabled),
Input(DynInput),
Interrupt(DynInterrupt),
Output(DynOutput),
Alternate(DynAlternate),
}
/// Value-level variant of [`DynPinMode`] for floating disabled mode
pub const DYN_FLOATING_DISABLED: DynPinMode = DynPinMode::Disabled(DynDisabled::Floating);
/// Value-level variant of [`DynPinMode`] for pull-down disabled mode
pub const DYN_PULL_DOWN_DISABLED: DynPinMode = DynPinMode::Disabled(DynDisabled::PullDown);
/// Value-level variant of [`DynPinMode`] for pull-up disabled mode
pub const DYN_PULL_UP_DISABLED: DynPinMode = DynPinMode::Disabled(DynDisabled::PullUp);
/// Value-level variant of [`DynPinMode`] for floating input mode
pub const DYN_FLOATING_INPUT: DynPinMode = DynPinMode::Input(DynInput::Floating);
/// Value-level variant of [`DynPinMode`] for pull-down input mode
pub const DYN_PULL_DOWN_INPUT: DynPinMode = DynPinMode::Input(DynInput::PullDown);
/// Value-level variant of [`DynPinMode`] for pull-up input mode
pub const DYN_PULL_UP_INPUT: DynPinMode = DynPinMode::Input(DynInput::PullUp);
/// Value-level variant of [`DynPinMode`] for floating interrupt mode
pub const DYN_FLOATING_INTERRUPT: DynPinMode = DynPinMode::Interrupt(DynInterrupt::Floating);
/// Value-level variant of [`DynPinMode`] for pull-down interrupt mode
pub const DYN_PULL_DOWN_INTERRUPT: DynPinMode = DynPinMode::Interrupt(DynInterrupt::PullDown);
/// Value-level variant of [`DynPinMode`] for pull-up interrupt mode
pub const DYN_PULL_UP_INTERRUPT: DynPinMode = DynPinMode::Interrupt(DynInterrupt::PullUp);
/// Value-level variant of [`DynPinMode`] for push-pull output mode
pub const DYN_PUSH_PULL_OUTPUT: DynPinMode = DynPinMode::Output(DynOutput::PushPull);
/// Value-level variant of [`DynPinMode`] for readable push-pull output mode
pub const DYN_READABLE_OUTPUT: DynPinMode = DynPinMode::Output(DynOutput::Readable);
macro_rules! dyn_alternate {
( $($Letter:ident),+ ) => {
paste! {
$(
#[
doc = "Value-level variant of [`DynPinMode`] for alternate "
"peripheral function " $Letter
]
pub const [<DYN_ALTERNATE_ $Letter>]: DynPinMode =
DynPinMode::Alternate(DynAlternate::$Letter);
)+
}
};
}
dyn_alternate!(B, C, D, E, F, G);
#[cfg(any(feature = "samd21", feature = "min-samd51g"))]
dyn_alternate!(H);
#[cfg(feature = "min-samd51g")]
dyn_alternate!(I, J, K, L, M, N);
//==============================================================================
// DynGroup & DynPinId
//==============================================================================
/// Value-level `enum` for pin groups
#[derive(PartialEq, Clone, Copy)]
pub enum DynGroup {
A,
#[cfg(any(feature = "samd21", feature = "min-samd51g"))]
B,
#[cfg(feature = "min-samd51n")]
C,
#[cfg(feature = "min-samd51p")]
D,
}
/// Value-level `struct` representing pin IDs
#[derive(PartialEq, Clone, Copy)]
pub struct DynPinId {
pub group: DynGroup,
pub num: u8,
}
//==============================================================================
// DynRegisters
//==============================================================================
/// Provide a safe register interface for [`DynPin`]s
///
/// This `struct` takes ownership of a [`DynPinId`] and provides an API to
/// access the corresponding regsiters.
struct DynRegisters {
id: DynPinId,
}
// [`DynRegisters`] takes ownership of the [`DynPinId`], and [`DynPin`]
// guarantees that each pin is a singleton, so this implementation is safe.
unsafe impl RegisterInterface for DynRegisters {
#[inline]
fn id(&self) -> DynPinId {
self.id
}
}
impl DynRegisters {
/// Create a new instance of [`DynRegisters`]
///
/// # Safety
///
/// Users must never create two simultaneous instances of this `struct` with
/// the same [`DynPinId`]
#[inline]
unsafe fn new(id: DynPinId) -> Self {
DynRegisters { id }
}
}
//==============================================================================
// Error
//==============================================================================
/// GPIO error type
///
/// [`DynPin`]s are not tracked and verified at compile-time, so run-time
/// operations are fallible. This `enum` represents the corresponding errors.
pub enum Error {
/// The pin did not have the correct ID or mode for the requested operation
InvalidPinType,
}
//==============================================================================
// DynPin
//==============================================================================
/// A value-level pin, parameterized by [`DynPinId`] and [`DynPinMode`]
///
/// This type acts as a type-erased version of [`Pin`]. Every pin is represented
/// by the same type, and pins are tracked and distinguished at run-time.
pub struct DynPin {
regs: DynRegisters,
mode: DynPinMode,
}
impl DynPin {
/// Create a new [`DynPin`]
///
/// # Safety
///
/// Each [`DynPin`] must be a singleton. For a given [`DynPinId`], there
/// must be at most one corresponding [`DynPin`] in existence at any given
/// time. Violating this requirement is `unsafe`.
#[inline]
unsafe fn new(id: DynPinId, mode: DynPinMode) -> Self {
DynPin {
regs: DynRegisters::new(id),
mode,
}
}
/// Return a copy of the pin ID
#[inline]
pub fn id(&self) -> DynPinId {
self.regs.id
}
/// Return a copy of the pin mode
#[inline]
pub fn mode(&self) -> DynPinMode {
self.mode
}
/// Convert the pin to the requested [`DynPinMode`]
#[inline]
pub fn into_mode(&mut self, mode: DynPinMode) {
// Only modify registers if we are actually changing pin mode
if mode != self.mode {
self.regs.change_mode(mode);
self.mode = mode;
}
}
/// Disable the pin and set it to float
#[inline]
pub fn into_floating_disabled(&mut self) {
self.into_mode(DYN_FLOATING_DISABLED);
}
/// Disable the pin and set it to pull down
#[inline]
pub fn into_pull_down_disabled(&mut self) {
self.into_mode(DYN_PULL_DOWN_DISABLED);
}
/// Disable the pin and set it to pull up
#[inline]
pub fn into_pull_up_disabled(&mut self) {
self.into_mode(DYN_PULL_UP_DISABLED);
}
/// Configure the pin to operate as a floating input
#[inline]
pub fn into_floating_input(&mut self) {
self.into_mode(DYN_FLOATING_INPUT);
}
/// Configure the pin to operate as a pulled down input
#[inline]
pub fn into_pull_down_input(&mut self) {
self.into_mode(DYN_PULL_DOWN_INPUT);
}
/// Configure the pin to operate as a pulled up input
#[inline]
pub fn into_pull_up_input(&mut self) {
self.into_mode(DYN_PULL_UP_INPUT);
}
/// Configure the pin to operate as a floating interrupt
#[inline]
pub fn into_floating_interrupt(&mut self) {
self.into_mode(DYN_FLOATING_INTERRUPT);
}
/// Configure the pin to operate as a pulled down interrupt
#[inline]
pub fn into_pull_down_interrupt(&mut self) {
self.into_mode(DYN_PULL_DOWN_INTERRUPT);
}
/// Configure the pin to operate as a pulled up interrupt
#[inline]
pub fn into_pull_up_interrupt(&mut self) {
self.into_mode(DYN_PULL_UP_INTERRUPT);
}
/// Configure the pin to operate as a push-pull output
#[inline]
pub fn into_push_pull_output(&mut self) {
self.into_mode(DYN_PUSH_PULL_OUTPUT);
}
/// Configure the pin to operate as a readable push pull output
#[inline]
pub fn into_readable_output(&mut self) {
self.into_mode(DYN_READABLE_OUTPUT);
}
/// Configure the pin to operate as the corresponding peripheral function.
///
/// The `config` argument indicates the desired peripheral function.
#[inline]
pub fn into_alternate(&mut self, config: DynAlternate) {
self.into_mode(DynPinMode::Alternate(config));
}
/// Read the current drive strength of the pin.
///
/// The drive strength is reset to normal on every change in pin mode.
#[inline]
pub fn get_drive_strength(&self) -> bool {
self.regs.read_drive_strength()
}
/// Set the drive strength for the pin.
///
/// The drive strength is reset to normal on every change in pin mode.
#[inline]
pub fn set_drive_strength(&mut self, stronger: bool) {
self.regs.write_drive_strength(stronger);
}
#[inline]
fn _read(&self) -> Result<bool, Error> {
match self.mode {
DynPinMode::Input(_) | DYN_READABLE_OUTPUT => Ok(self.regs.read_pin()),
_ => Err(Error::InvalidPinType),
}
}
#[inline]
fn _write(&mut self, bit: bool) -> Result<(), Error> {
match self.mode {
DynPinMode::Output(_) => {
self.regs.write_pin(bit);
Ok(())
}
_ => Err(Error::InvalidPinType),
}
}
#[inline]
fn _toggle(&mut self) -> Result<(), Error> {
match self.mode {
DynPinMode::Output(_) => {
self.regs.toggle_pin();
Ok(())
}
_ => Err(Error::InvalidPinType),
}
}
#[inline]
fn _read_out(&self) -> Result<bool, Error> {
match self.mode {
DYN_READABLE_OUTPUT => Ok(self.regs.read_out_pin()),
_ => Err(Error::InvalidPinType),
}
}
#[inline]
fn _is_low(&self) -> Result<bool, Error> {
Ok(self._read()? == false)
}
#[inline]
fn _is_high(&self) -> Result<bool, Error> {
Ok(self._read()? == true)
}
#[inline]
fn _set_low(&mut self) -> Result<(), Error> {
self._write(false)
}
#[inline]
fn _set_high(&mut self) -> Result<(), Error> {
self._write(true)
}
#[inline]
fn _is_set_low(&self) -> Result<bool, Error> {
Ok(self._read_out()? == false)
}
#[inline]
fn _is_set_high(&self) -> Result<bool, Error> {
Ok(self._read_out()? == true)
}
}
//==============================================================================
// Convert between Pin and DynPin
//==============================================================================
impl<I, M> From<Pin<I, M>> for DynPin
where
I: PinId,
M: PinMode,
{
/// Erase the type-level information in a [`Pin`] and return a value-level
/// [`DynPin`]
#[inline]
fn from(_pin: Pin<I, M>) -> Self {
// The `Pin` is consumed, so it is safe to replace it with the
// corresponding `DynPin`
unsafe { DynPin::new(I::DYN, M::DYN) }
}
}
impl<I, M> TryFrom<DynPin> for Pin<I, M>
where
I: PinId,
M: PinMode,
{
type Error = Error;
/// Try to recreate a type-level [`Pin`] from a value-level [`DynPin`]
///
/// There is no way for the compiler to know if the conversion will be
/// successful at compile-time. We must verify the conversion at run-time
/// or refuse to perform it.
#[inline]
fn try_from(pin: DynPin) -> Result<Self, Error> {
if pin.regs.id == I::DYN && pin.mode == M::DYN {
// The `DynPin` is consumed, so it is safe to replace it with the
// corresponding `Pin`
Ok(unsafe { Self::new() })
} else {
Err(Error::InvalidPinType)
}
}
}
//==============================================================================
// Embedded HAL traits
//==============================================================================
impl OutputPin for DynPin {
type Error = Error;
#[inline]
fn set_high(&mut self) -> Result<(), Self::Error> {
self._set_high()
}
#[inline]
fn set_low(&mut self) -> Result<(), Self::Error> {
self._set_low()
}
}
#[cfg(feature = "unproven")]
impl InputPin for DynPin {
type Error = Error;
#[inline]
fn is_high(&self) -> Result<bool, Self::Error> {
self._is_high()
}
#[inline]
fn is_low(&self) -> Result<bool, Self::Error> {
self._is_low()
}
}
#[cfg(feature = "unproven")]
impl ToggleableOutputPin for DynPin {
type Error = Error;
#[inline]
fn toggle(&mut self) -> Result<(), Self::Error> {
self._toggle()
}
}
#[cfg(feature = "unproven")]
impl StatefulOutputPin for DynPin {
#[inline]
fn is_set_high(&self) -> Result<bool, Self::Error> {
self._is_set_high()
}
#[inline]
fn is_set_low(&self) -> Result<bool, Self::Error> {
self._is_set_low()
}
}