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//! Pad configuration
use crate::Iomuxc;
use core::ptr;
/// Applies the configuration `config` for the supplied pad
///
/// `configure` lets you specify the pad's drive strength, speed, pull-up or pull-down
/// resistors, and other configurations. See [`Config`](struct.Config.html)
/// for possible configurations.
///
/// # Example
///
/// ```no_run
/// use imxrt_iomuxc::{configure, Config, OpenDrain, PullKeeper};
/// # use imxrt_iomuxc::imxrt1060::gpio_ad_b0::GPIO_AD_B0_03;
///
/// const CONFIG: Config = Config::zero()
/// .set_open_drain(OpenDrain::Enabled)
/// .set_pull_keeper(Some(PullKeeper::Pullup100k));
///
/// let mut pad = unsafe { GPIO_AD_B0_03::new() };
///
/// configure(&mut pad, CONFIG);
/// ```
#[inline(always)]
pub fn configure<I: Iomuxc>(pad: &mut I, config: Config) {
// Safety: same justification as set_sion.
unsafe {
let cfg = ptr::read_volatile(pad.pad());
let cfg = (cfg & !config.mask) | config.value;
ptr::write_volatile(pad.pad(), cfg);
}
}
const HYSTERESIS_SHIFT: u32 = 16;
const HYSTERESIS_MASK: u32 = 1 << HYSTERESIS_SHIFT;
/// The hysteresis (HYS) bit controls whether a pin acts as a Schmitt trigger,
/// which is a comparator remembering its last input state (hysteresis).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
pub enum Hysteresis {
Enabled = 1 << HYSTERESIS_SHIFT,
Disabled = 0 << HYSTERESIS_SHIFT,
}
const PULLUPDOWN_SHIFT: u32 = 14;
const PULLUPDOWN_MASK: u32 = 0b11 << PULLUPDOWN_SHIFT;
/// Controls signals to select pull-up or pull-down internal resistance strength.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
#[deprecated(since = "0.2.0", note = "Use PullKeeper and Config::set_pull_keeper")]
pub enum PullUpDown {
/// 100KOhm pull Down
Pulldown100k = 0b00 << PULLUPDOWN_SHIFT,
/// 47KOhm pull up
Pullup47k = 0b01 << PULLUPDOWN_SHIFT,
/// 100KOhm pull up
Pullup100k = 0b10 << PULLUPDOWN_SHIFT,
/// 22KOhm pull up
Pullup22k = 0b11 << PULLUPDOWN_SHIFT,
}
const PULL_KEEP_SELECT_SHIFT: u32 = 13;
const PULL_KEEP_SELECT_MASK: u32 = 1 << PULL_KEEP_SELECT_SHIFT;
/// Control signal to enable internal pull-up/down resistors or pad keeper functionality.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
#[deprecated(since = "0.2.0", note = "Use PullKeeper and Config::set_pull_keeper")]
pub enum PullKeepSelect {
/// Keep the previous output value when the output driver is disabled.
Keeper = 0 << PULL_KEEP_SELECT_SHIFT,
/// Pull-up or pull-down (determined by [`PullUpDown`](struct.PullUpDown.html) flags).
Pull = 1 << PULL_KEEP_SELECT_SHIFT,
}
const PULLKEEP_SHIFT: u32 = 12;
const PULLKEEP_MASK: u32 = 1 << PULLKEEP_SHIFT;
/// Enable or disable the pull / keeper functionality
///
/// When the pull/keeper is disabled, `PullKeepSelect` and `PullUpDown` have no functionality.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
#[deprecated(since = "0.2.0", note = "Use PullKeeper and Config::set_pull_keeper")]
pub enum PullKeep {
Enabled = 1 << PULLKEEP_SHIFT,
Disabled = 0 << PULLKEEP_SHIFT,
}
/// Derives a pull/keep configuration from
/// the field-specific enums.
///
/// Used to define the public API.
#[allow(deprecated)]
const fn pull_keeper(select: PullKeepSelect, pull: Option<PullUpDown>) -> u32 {
PULLKEEP_MASK
| (select as u32)
| match pull {
None => 0u32,
Some(pull) => pull as u32,
}
}
const PULL_KEEPER_MASK: u32 = PULLKEEP_MASK | PULLUPDOWN_MASK | PULL_KEEP_SELECT_MASK;
/// The pull up, pull down, or keeper configuration.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
#[repr(u32)]
#[allow(deprecated)]
pub enum PullKeeper {
/// 100KOhm pull **down**
Pulldown100k = pull_keeper(PullKeepSelect::Pull, Some(PullUpDown::Pulldown100k)),
/// 22KOhm pull **up**
Pullup22k = pull_keeper(PullKeepSelect::Pull, Some(PullUpDown::Pullup22k)),
/// 47KOhm pull **up**
Pullup47k = pull_keeper(PullKeepSelect::Pull, Some(PullUpDown::Pullup47k)),
/// 100KOhm pull **up**
Pullup100k = pull_keeper(PullKeepSelect::Pull, Some(PullUpDown::Pullup100k)),
/// Use the keeper, instead of a pull up or pull
/// down resistor.
///
/// From the reference manual,
///
/// > A simple latch to hold the input value when OVDD is powered down, or the first inverter
/// > is tri-stated. Input buffer’s keeper is always enabled for all the pads.
Keeper = pull_keeper(PullKeepSelect::Keeper, None),
}
const OPENDRAIN_SHIFT: u32 = 11;
const OPENDRAIN_MASK: u32 = 1 << OPENDRAIN_SHIFT;
/// Open Drain Enable Field
///
/// If enabled, the output driver drives only logic 0. The drain of the
/// internal transistor is open. It means that logic 1 has to be driven by
/// an external component. This option is essential if connection between
/// the pad and an external component is bi-directional. If disabled, then
/// the output driver drives logic 1 and logic 0.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
pub enum OpenDrain {
Enabled = 1 << OPENDRAIN_SHIFT,
Disabled = 0 << OPENDRAIN_SHIFT,
}
const SPEED_SHIFT: u32 = 6;
const SPEED_MASK: u32 = 0b11 << SPEED_SHIFT;
/// Sets electrical characteristics of a pin in a given frequency range
///
/// Speed is a selectable bit field that sets electrical characteristics of
/// a pin in a given frequency range. This field provides additional 2-bit
/// slew rate control. These options can either increase the output driver
/// current in the higher frequency range, or reduce the switching noise in
/// the lower frequency range.
///
/// The operational frequency on GPIO pads is dependent on slew rate (SRE),
/// speed (SPEED), and supply voltage (OVDD).
///
/// See Operating Frequency table in the GPIO block guide in the reference
/// manual for more details.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
pub enum Speed {
Low = 0b00 << SPEED_SHIFT,
Medium = 0b01 << SPEED_SHIFT,
Fast = 0b10 << SPEED_SHIFT,
Max = 0b11 << SPEED_SHIFT,
}
const DRIVE_STRENGTH_SHIFT: u32 = 3;
const DRIVE_STRENGTH_MASK: u32 = 0b111 << DRIVE_STRENGTH_SHIFT;
/// Drive strength
///
/// The drive strength enable (DSE) can be explained as series resistance between an ideal driver’s
/// output and its load. To achieve maximal transferred power, the impedance of the driver has to
/// match the load impedance.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
pub enum DriveStrength {
Disabled = 0b000 << DRIVE_STRENGTH_SHIFT,
/// 150 Ohm @ 3.3V, 260 Ohm@1.8V
R0 = 0b001 << DRIVE_STRENGTH_SHIFT,
/// R0 / 2
R0_2 = 0b010 << DRIVE_STRENGTH_SHIFT,
/// R0 / 3
R0_3 = 0b011 << DRIVE_STRENGTH_SHIFT,
/// R0 / 4
R0_4 = 0b100 << DRIVE_STRENGTH_SHIFT,
R0_5 = 0b101 << DRIVE_STRENGTH_SHIFT,
R0_6 = 0b110 << DRIVE_STRENGTH_SHIFT,
R0_7 = 0b111 << DRIVE_STRENGTH_SHIFT,
}
const SLEW_RATE_SHIFT: u32 = 0;
const SLEW_RATE_MASK: u32 = 1 << SLEW_RATE_SHIFT;
/// Slew Rate
///
/// This controls how fast the pin toggles between the two logic states.
/// Since rapidly changing states consume more power and generate spikes,
/// it should be enabled only when necessary.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
pub enum SlewRate {
Fast = 1 << SLEW_RATE_SHIFT,
Slow = 0 << SLEW_RATE_SHIFT,
}
/// A configuration capable of compile-time, `const` configuration:
///
/// ```
/// use imxrt_iomuxc::{Config, SlewRate, Hysteresis};
///
/// const UART_TX_CONFIG: Config = Config::zero()
/// .set_slew_rate(SlewRate::Fast)
/// .set_hysteresis(Hysteresis::Enabled);
/// ```
///
/// Use [`configure()`](fn.configure.html) to set configurations to pads.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub struct Config {
value: u32,
mask: u32,
}
impl Config {
/// When we create the zero mask, we set all bits high. But,
/// the highest usable bit in the pad register is bit 16. We
/// can use a higher bit to represent if the config is generated
/// from `zero()`, or if it was generated from `modify()`.
const ZERO_BIT: u32 = 1 << 31;
/// Create a `Config` that will zero any unspecified field
///
/// This may *not* represent any register's reset value. A config that's
/// created using `zero()` will have the effect of writing *all* fields
/// to the register. Those that are not set explicitly set are written as zero.
///
/// ```no_run
/// # use imxrt_iomuxc::{Iomuxc, imxrt1060::gpio_ad_b0::GPIO_AD_B0_13};
/// # let mut gpio_ad_b0_13 = unsafe { GPIO_AD_B0_13::new() };
/// use imxrt_iomuxc::{
/// Config, configure, SlewRate,
/// Hysteresis, PullKeeper, DriveStrength
/// };
///
/// // Set a configuration
/// configure(
/// &mut gpio_ad_b0_13,
/// Config::zero()
/// .set_slew_rate(SlewRate::Fast)
/// .set_drive_strength(DriveStrength::R0_7)
/// );
/// // DriveStrength::R0_7 as u32 | SlewRate::Fast as u32
///
/// // Completely change that configuration
/// configure(
/// &mut gpio_ad_b0_13,
/// Config::zero()
/// .set_hysteresis(Hysteresis::Enabled)
/// .set_pull_keeper(Some(PullKeeper::Pullup22k))
/// );
/// // Hysteresis::Enabled as u32 | PullKeeper::Pullup22k as u32
/// //
/// // Notice that SlewRate and DriveStrength were set to zero.
/// ```
pub const fn zero() -> Self {
Config {
value: 0u32,
mask: 0xFFFF_FFFFu32,
}
}
/// Create a `Config` that will only modify the specified fields
///
/// Any field that is is *not* specified in the configuration will not be touched.
///
/// ```no_run
/// # use imxrt_iomuxc::{Iomuxc, imxrt1060::gpio_ad_b0::GPIO_AD_B0_13};
/// # let mut gpio_ad_b0_13 = unsafe { GPIO_AD_B0_13::new() };
/// use imxrt_iomuxc::{Config, configure, SlewRate, DriveStrength, Hysteresis};
///
/// // Assume a starting value in the register...
/// configure(
/// &mut gpio_ad_b0_13,
/// Config::zero()
/// .set_slew_rate(SlewRate::Fast)
/// .set_drive_strength(DriveStrength::R0_7)
/// );
/// // DriveStrength::R0_7 as u32 | SlewRate::Fast as u32
///
/// // Now change the slew rate, and add hysteresis
/// configure(
/// &mut gpio_ad_b0_13,
/// Config::modify()
/// .set_slew_rate(SlewRate::Slow)
/// .set_hysteresis(Hysteresis::Enabled)
/// );
/// // DriveStrength::R0_7 as u32 | Hysteresis::Enabled as u32
/// //
/// // Notice that the DriveStrength field is preserved.
/// ```
pub const fn modify() -> Self {
Config {
value: 0u32,
mask: 0u32,
}
}
/// Returns `true` if this `Config` was created using [`zero()`](struct.Config.html#method.zero), meaning that it will
/// zero any unspecified fields. If `false`, this config was created using [`modify()`](struct.Config.html#method.modify),
/// which will not touch unspecified fields.
///
/// ```
/// use imxrt_iomuxc::Config;
///
/// assert!(Config::zero().is_zero());
/// assert!(!Config::modify().is_zero());
/// ```
pub const fn is_zero(&self) -> bool {
self.mask & Self::ZERO_BIT != 0
}
/// Set the hysteresis bit
pub const fn set_hysteresis(mut self, hys: Hysteresis) -> Self {
self.value = (self.value & !HYSTERESIS_MASK) | (hys as u32);
self.mask |= HYSTERESIS_MASK;
self
}
/// Set the pull up / pull down / keeper configuration.
///
/// A `None` value disables the pull / keeper function.
pub const fn set_pull_keeper(mut self, pk: Option<PullKeeper>) -> Self {
let pk = match pk {
None => 0u32,
Some(pk) => pk as u32,
};
self.value = (self.value & !PULL_KEEPER_MASK) | pk;
self.mask |= PULL_KEEPER_MASK;
self
}
/// Set the pull-up / pull-down value
#[deprecated(since = "0.2.0", note = "Use PullKeeper and Config::set_pull_keeper")]
#[allow(deprecated)]
pub const fn set_pullupdown(mut self, pud: PullUpDown) -> Self {
self.value = (self.value & !PULLUPDOWN_MASK) | (pud as u32);
self.mask |= PULLUPDOWN_MASK;
self
}
/// Set the the pull-up / pull-down or keeper selection bit
#[deprecated(since = "0.2.0", note = "Use PullKeeper and Config::set_pull_keeper")]
#[allow(deprecated)]
pub const fn set_pull_keep_select(mut self, pke: PullKeepSelect) -> Self {
self.value = (self.value & !PULL_KEEP_SELECT_MASK) | (pke as u32);
self.mask |= PULL_KEEP_SELECT_MASK;
self
}
/// Set the flag that enables the keeper or pull-up / pull-down configuration
#[deprecated(since = "0.2.0", note = "Use PullKeeper and Config::set_pull_keeper")]
#[allow(deprecated)]
pub const fn set_pull_keep(mut self, pk: PullKeep) -> Self {
self.value = (self.value & !PULLKEEP_MASK) | (pk as u32);
self.mask |= PULLKEEP_MASK;
self
}
/// Set the open drain value
pub const fn set_open_drain(mut self, od: OpenDrain) -> Self {
self.value = (self.value & !OPENDRAIN_MASK) | (od as u32);
self.mask |= OPENDRAIN_MASK;
self
}
/// Set the pin speed
pub const fn set_speed(mut self, speed: Speed) -> Self {
self.value = (self.value & !SPEED_MASK) | (speed as u32);
self.mask |= SPEED_MASK;
self
}
/// Set the drive strength
pub const fn set_drive_strength(mut self, dse: DriveStrength) -> Self {
self.value = (self.value & !DRIVE_STRENGTH_MASK) | (dse as u32);
self.mask |= DRIVE_STRENGTH_MASK;
self
}
/// Set the slew rate
pub const fn set_slew_rate(mut self, sre: SlewRate) -> Self {
self.value = (self.value & !SLEW_RATE_MASK) | (sre as u32);
self.mask |= SLEW_RATE_MASK;
self
}
}
/// A workaround to set a pad's open drain configuration.
///
/// This is a best effort until we can use the [`config`] API on
/// the 1170. See the issue tracker for more details.
/// https://github.com/imxrt-rs/imxrt-iomuxc/issues/28
pub(crate) fn set_open_drain<I: Iomuxc>(_pad: &mut I) {
#[cfg(any(feature = "imxrt1010", feature = "imxrt1020", feature = "imxrt1060"))]
configure(_pad, Config::modify().set_open_drain(OpenDrain::Enabled));
}
#[cfg(test)]
mod tests {
use super::*;
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Pad(u32);
const PAD_ALL_HIGH: Pad = Pad(0x0001_FFFFu32);
/// The high bits represent the valid fields in pad registers.
const PAD_BITMASK: u32 = 0b1_1111_1000_1111_1001u32;
impl crate::private::Sealed for Pad {}
unsafe impl Iomuxc for Pad {
fn mux(&mut self) -> *mut u32 {
panic!("Nothing calls mux() in these tests");
}
fn pad(&mut self) -> *mut u32 {
&mut self.0 as *mut _
}
}
#[test]
fn zero() {
let mut pad = PAD_ALL_HIGH;
configure(&mut pad, Config::zero());
assert_eq!(pad.0, 0);
}
#[test]
fn zero_set_all() {
let mut pad = PAD_ALL_HIGH;
const CONFIG: Config = Config::zero()
.set_hysteresis(Hysteresis::Enabled)
.set_pull_keeper(Some(PullKeeper::Pullup22k))
.set_open_drain(OpenDrain::Enabled)
.set_speed(Speed::Max)
.set_drive_strength(DriveStrength::R0_7)
.set_slew_rate(SlewRate::Fast);
configure(&mut pad, CONFIG);
assert_eq!(pad.0, PAD_BITMASK);
}
#[test]
fn modify_clear_all() {
let mut pad = Pad(PAD_BITMASK);
const CONFIG: Config = Config::modify()
.set_hysteresis(Hysteresis::Disabled)
.set_pull_keeper(None)
.set_open_drain(OpenDrain::Disabled)
.set_speed(Speed::Low)
.set_drive_strength(DriveStrength::Disabled)
.set_slew_rate(SlewRate::Slow);
configure(&mut pad, CONFIG);
assert_eq!(pad.0, 0);
}
#[test]
fn pull_keeper_none() {
let mut pad = Pad(0);
configure(&mut pad, Config::zero().set_pull_keeper(None));
assert_eq!(pad.0, 0);
}
#[test]
fn pull_keeper_keeper() {
let mut pad = Pad(0);
configure(
&mut pad,
Config::zero().set_pull_keeper(Some(PullKeeper::Keeper)),
);
assert_eq!(pad.0, 1 << 12);
}
#[test]
fn pull_keeper_pullupdown() {
struct ConfigToField {
config: PullKeeper,
value: u32,
}
const TESTS: [ConfigToField; 4] = [
ConfigToField {
config: PullKeeper::Pulldown100k,
value: 0 << 14,
},
ConfigToField {
config: PullKeeper::Pullup100k,
value: 2 << 14,
},
ConfigToField {
config: PullKeeper::Pullup22k,
value: 3 << 14,
},
ConfigToField {
config: PullKeeper::Pullup47k,
value: 1 << 14,
},
];
for test in TESTS {
let mut pad = Pad(0);
configure(&mut pad, Config::zero().set_pull_keeper(Some(test.config)));
assert_eq!(pad.0, 1 << 12 | 1 << 13 | test.value);
}
}
#[test]
fn set_open_drain() {
let mut pad = Pad(0);
super::set_open_drain(&mut pad);
assert_eq!(pad.0, 1 << 11);
let mut pad = Pad(0xFFFF_F7FF);
super::set_open_drain(&mut pad);
assert_eq!(pad.0, 0xFFFFFFFF);
}
}
/// ```rust
/// use imxrt_iomuxc::{Config, PullKeeper};
///
/// const CONFIG: Config = Config::zero().set_pull_keeper(Some(PullKeeper::Keeper));
#[cfg(doctest)]
struct PullKeeperConstant;