nrf: add PWM

8 files changed, 366 insertions, 0 deletions

diff --git a/embassy-nrf-examples/src/bin/pwm.rs b/embassy-nrf-examples/src/bin/pwm.rs
new file mode 100644
index 000000000..6efcf22d2
--- /dev/null
+++ b/embassy-nrf-examples/src/bin/pwm.rs
@@ -0,0 +1,104 @@
+#![no_std]
+#![no_main]
+#![feature(min_type_alias_impl_trait)]
+#![feature(impl_trait_in_bindings)]
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+use defmt::{panic, *};
+use embassy::executor::Spawner;
+use embassy::time::{Duration, Timer};
+use embassy_nrf::pwm::{Prescaler, Pwm};
+use embassy_nrf::{interrupt, Peripherals};
+
+// for i in range(1024): print(int((math.sin(i/512*math.pi)*0.4+0.5)**2*32767), ', ', end='')
+static DUTY: [u16; 1024] = [
+    8191, 8272, 8353, 8434, 8516, 8598, 8681, 8764, 8847, 8931, 9015, 9099, 9184, 9269, 9354, 9440,
+    9526, 9613, 9700, 9787, 9874, 9962, 10050, 10139, 10227, 10316, 10406, 10495, 10585, 10675,
+    10766, 10857, 10948, 11039, 11131, 11223, 11315, 11407, 11500, 11592, 11685, 11779, 11872,
+    11966, 12060, 12154, 12248, 12343, 12438, 12533, 12628, 12723, 12818, 12914, 13010, 13106,
+    13202, 13298, 13394, 13491, 13587, 13684, 13781, 13878, 13975, 14072, 14169, 14266, 14364,
+    14461, 14558, 14656, 14754, 14851, 14949, 15046, 15144, 15242, 15339, 15437, 15535, 15632,
+    15730, 15828, 15925, 16023, 16120, 16218, 16315, 16412, 16510, 16607, 16704, 16801, 16898,
+    16995, 17091, 17188, 17284, 17380, 17477, 17572, 17668, 17764, 17859, 17955, 18050, 18145,
+    18239, 18334, 18428, 18522, 18616, 18710, 18803, 18896, 18989, 19082, 19174, 19266, 19358,
+    19449, 19540, 19631, 19722, 19812, 19902, 19991, 20081, 20169, 20258, 20346, 20434, 20521,
+    20608, 20695, 20781, 20867, 20952, 21037, 21122, 21206, 21290, 21373, 21456, 21538, 21620,
+    21701, 21782, 21863, 21943, 22022, 22101, 22179, 22257, 22335, 22412, 22488, 22564, 22639,
+    22714, 22788, 22861, 22934, 23007, 23079, 23150, 23220, 23290, 23360, 23429, 23497, 23564,
+    23631, 23698, 23763, 23828, 23892, 23956, 24019, 24081, 24143, 24204, 24264, 24324, 24383,
+    24441, 24499, 24555, 24611, 24667, 24721, 24775, 24828, 24881, 24933, 24983, 25034, 25083,
+    25132, 25180, 25227, 25273, 25319, 25363, 25407, 25451, 25493, 25535, 25575, 25615, 25655,
+    25693, 25731, 25767, 25803, 25838, 25873, 25906, 25939, 25971, 26002, 26032, 26061, 26089,
+    26117, 26144, 26170, 26195, 26219, 26242, 26264, 26286, 26307, 26327, 26346, 26364, 26381,
+    26397, 26413, 26427, 26441, 26454, 26466, 26477, 26487, 26496, 26505, 26512, 26519, 26525,
+    26530, 26534, 26537, 26539, 26540, 26541, 26540, 26539, 26537, 26534, 26530, 26525, 26519,
+    26512, 26505, 26496, 26487, 26477, 26466, 26454, 26441, 26427, 26413, 26397, 26381, 26364,
+    26346, 26327, 26307, 26286, 26264, 26242, 26219, 26195, 26170, 26144, 26117, 26089, 26061,
+    26032, 26002, 25971, 25939, 25906, 25873, 25838, 25803, 25767, 25731, 25693, 25655, 25615,
+    25575, 25535, 25493, 25451, 25407, 25363, 25319, 25273, 25227, 25180, 25132, 25083, 25034,
+    24983, 24933, 24881, 24828, 24775, 24721, 24667, 24611, 24555, 24499, 24441, 24383, 24324,
+    24264, 24204, 24143, 24081, 24019, 23956, 23892, 23828, 23763, 23698, 23631, 23564, 23497,
+    23429, 23360, 23290, 23220, 23150, 23079, 23007, 22934, 22861, 22788, 22714, 22639, 22564,
+    22488, 22412, 22335, 22257, 22179, 22101, 22022, 21943, 21863, 21782, 21701, 21620, 21538,
+    21456, 21373, 21290, 21206, 21122, 21037, 20952, 20867, 20781, 20695, 20608, 20521, 20434,
+    20346, 20258, 20169, 20081, 19991, 19902, 19812, 19722, 19631, 19540, 19449, 19358, 19266,
+    19174, 19082, 18989, 18896, 18803, 18710, 18616, 18522, 18428, 18334, 18239, 18145, 18050,
+    17955, 17859, 17764, 17668, 17572, 17477, 17380, 17284, 17188, 17091, 16995, 16898, 16801,
+    16704, 16607, 16510, 16412, 16315, 16218, 16120, 16023, 15925, 15828, 15730, 15632, 15535,
+    15437, 15339, 15242, 15144, 15046, 14949, 14851, 14754, 14656, 14558, 14461, 14364, 14266,
+    14169, 14072, 13975, 13878, 13781, 13684, 13587, 13491, 13394, 13298, 13202, 13106, 13010,
+    12914, 12818, 12723, 12628, 12533, 12438, 12343, 12248, 12154, 12060, 11966, 11872, 11779,
+    11685, 11592, 11500, 11407, 11315, 11223, 11131, 11039, 10948, 10857, 10766, 10675, 10585,
+    10495, 10406, 10316, 10227, 10139, 10050, 9962, 9874, 9787, 9700, 9613, 9526, 9440, 9354, 9269,
+    9184, 9099, 9015, 8931, 8847, 8764, 8681, 8598, 8516, 8434, 8353, 8272, 8191, 8111, 8031, 7952,
+    7873, 7794, 7716, 7638, 7561, 7484, 7407, 7331, 7255, 7180, 7105, 7031, 6957, 6883, 6810, 6738,
+    6665, 6594, 6522, 6451, 6381, 6311, 6241, 6172, 6104, 6036, 5968, 5901, 5834, 5767, 5702, 5636,
+    5571, 5507, 5443, 5379, 5316, 5253, 5191, 5130, 5068, 5008, 4947, 4888, 4828, 4769, 4711, 4653,
+    4596, 4539, 4482, 4426, 4371, 4316, 4261, 4207, 4153, 4100, 4047, 3995, 3943, 3892, 3841, 3791,
+    3741, 3691, 3642, 3594, 3546, 3498, 3451, 3404, 3358, 3312, 3267, 3222, 3178, 3134, 3090, 3047,
+    3005, 2962, 2921, 2879, 2839, 2798, 2758, 2719, 2680, 2641, 2603, 2565, 2528, 2491, 2454, 2418,
+    2382, 2347, 2312, 2278, 2244, 2210, 2177, 2144, 2112, 2080, 2048, 2017, 1986, 1956, 1926, 1896,
+    1867, 1838, 1810, 1781, 1754, 1726, 1699, 1673, 1646, 1620, 1595, 1570, 1545, 1520, 1496, 1472,
+    1449, 1426, 1403, 1380, 1358, 1336, 1315, 1294, 1273, 1252, 1232, 1212, 1192, 1173, 1154, 1135,
+    1117, 1099, 1081, 1063, 1046, 1029, 1012, 996, 980, 964, 948, 933, 918, 903, 888, 874, 860,
+    846, 833, 819, 806, 793, 781, 768, 756, 744, 733, 721, 710, 699, 688, 677, 667, 657, 647, 637,
+    627, 618, 609, 599, 591, 582, 574, 565, 557, 549, 541, 534, 526, 519, 512, 505, 498, 492, 485,
+    479, 473, 467, 461, 455, 450, 444, 439, 434, 429, 424, 419, 415, 410, 406, 402, 398, 394, 390,
+    386, 383, 379, 376, 373, 370, 367, 364, 361, 359, 356, 354, 351, 349, 347, 345, 343, 342, 340,
+    338, 337, 336, 334, 333, 332, 331, 330, 330, 329, 328, 328, 328, 327, 327, 327, 327, 327, 328,
+    328, 328, 329, 330, 330, 331, 332, 333, 334, 336, 337, 338, 340, 342, 343, 345, 347, 349, 351,
+    354, 356, 359, 361, 364, 367, 370, 373, 376, 379, 383, 386, 390, 394, 398, 402, 406, 410, 415,
+    419, 424, 429, 434, 439, 444, 450, 455, 461, 467, 473, 479, 485, 492, 498, 505, 512, 519, 526,
+    534, 541, 549, 557, 565, 574, 582, 591, 599, 609, 618, 627, 637, 647, 657, 667, 677, 688, 699,
+    710, 721, 733, 744, 756, 768, 781, 793, 806, 819, 833, 846, 860, 874, 888, 903, 918, 933, 948,
+    964, 980, 996, 1012, 1029, 1046, 1063, 1081, 1099, 1117, 1135, 1154, 1173, 1192, 1212, 1232,
+    1252, 1273, 1294, 1315, 1336, 1358, 1380, 1403, 1426, 1449, 1472, 1496, 1520, 1545, 1570, 1595,
+    1620, 1646, 1673, 1699, 1726, 1754, 1781, 1810, 1838, 1867, 1896, 1926, 1956, 1986, 2017, 2048,
+    2080, 2112, 2144, 2177, 2210, 2244, 2278, 2312, 2347, 2382, 2418, 2454, 2491, 2528, 2565, 2603,
+    2641, 2680, 2719, 2758, 2798, 2839, 2879, 2921, 2962, 3005, 3047, 3090, 3134, 3178, 3222, 3267,
+    3312, 3358, 3404, 3451, 3498, 3546, 3594, 3642, 3691, 3741, 3791, 3841, 3892, 3943, 3995, 4047,
+    4100, 4153, 4207, 4261, 4316, 4371, 4426, 4482, 4539, 4596, 4653, 4711, 4769, 4828, 4888, 4947,
+    5008, 5068, 5130, 5191, 5253, 5316, 5379, 5443, 5507, 5571, 5636, 5702, 5767, 5834, 5901, 5968,
+    6036, 6104, 6172, 6241, 6311, 6381, 6451, 6522, 6594, 6665, 6738, 6810, 6883, 6957, 7031, 7105,
+    7180, 7255, 7331, 7407, 7484, 7561, 7638, 7716, 7794, 7873, 7952, 8031, 8111,
+];
+
+#[embassy::main]
+async fn main(spawner: Spawner, p: Peripherals) {
+    let pwm = Pwm::new(p.PWM0, p.P0_13, p.P0_14, p.P0_16, p.P0_15);
+    pwm.set_prescaler(Prescaler::Div1);
+    info!("pwm initialized!");
+
+    let mut i = 0;
+    loop {
+        i += 1;
+        pwm.set_duty(0, DUTY[i % 1024]);
+        pwm.set_duty(1, DUTY[(i + 256) % 1024]);
+        pwm.set_duty(2, DUTY[(i + 512) % 1024]);
+        pwm.set_duty(3, DUTY[(i + 768) % 1024]);
+        Timer::after(Duration::from_millis(3)).await;
+    }
+}
diff --git a/embassy-nrf/src/chips/nrf52810.rs b/embassy-nrf/src/chips/nrf52810.rs
index 2e77a2fad..9e9f80090 100644
--- a/embassy-nrf/src/chips/nrf52810.rs
+++ b/embassy-nrf/src/chips/nrf52810.rs
@@ -18,6 +18,9 @@ embassy_extras::peripherals! {
     // SAADC
     SAADC,
 
+    // PWM
+    PWM0,
+
     // TIMER
     TIMER0,
     TIMER1,
@@ -115,6 +118,8 @@ impl_spim!(SPI0, SPIM0, SPIM0_SPIS0_SPI0);
 
 impl_twim!(TWI0, TWIM0, TWIM0_TWIS0_TWI0);
 
+impl_pwm!(PWM0, PWM0, PWM0);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52811.rs b/embassy-nrf/src/chips/nrf52811.rs
index b3ad5817a..a9ef0ed19 100644
--- a/embassy-nrf/src/chips/nrf52811.rs
+++ b/embassy-nrf/src/chips/nrf52811.rs
@@ -18,6 +18,9 @@ embassy_extras::peripherals! {
     // SAADC
     SAADC,
 
+    // PWM
+    PWM0,
+
     // TIMER
     TIMER0,
     TIMER1,
@@ -116,6 +119,8 @@ impl_spim!(SPI1, SPIM1, SPIM1_SPIS1_SPI1);
 
 impl_twim!(TWISPI0, TWIM0, TWIM0_TWIS0_TWI0_SPIM0_SPIS0_SPI0);
 
+impl_pwm!(PWM0, PWM0, PWM0);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52832.rs b/embassy-nrf/src/chips/nrf52832.rs
index ed94430e4..4e57f2fa4 100644
--- a/embassy-nrf/src/chips/nrf52832.rs
+++ b/embassy-nrf/src/chips/nrf52832.rs
@@ -21,6 +21,11 @@ embassy_extras::peripherals! {
     // SAADC
     SAADC,
 
+    // PWM
+    PWM0,
+    PWM1,
+    PWM2,
+
     // TIMER
     TIMER0,
     TIMER1,
@@ -123,6 +128,10 @@ impl_spim!(SPI2, SPIM2, SPIM2_SPIS2_SPI2);
 impl_twim!(TWISPI0, TWIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
 impl_twim!(TWISPI1, TWIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
 
+impl_pwm!(PWM0, PWM0, PWM0);
+impl_pwm!(PWM1, PWM1, PWM1);
+impl_pwm!(PWM2, PWM2, PWM2);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52833.rs b/embassy-nrf/src/chips/nrf52833.rs
index 080157d69..30b0ab007 100644
--- a/embassy-nrf/src/chips/nrf52833.rs
+++ b/embassy-nrf/src/chips/nrf52833.rs
@@ -22,6 +22,12 @@ embassy_extras::peripherals! {
     // SAADC
     SAADC,
 
+    // PWM
+    PWM0,
+    PWM1,
+    PWM2,
+    PWM3,
+
     // TIMER
     TIMER0,
     TIMER1,
@@ -144,6 +150,11 @@ impl_spim!(SPI3, SPIM3, SPIM3);
 impl_twim!(TWISPI0, TWIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
 impl_twim!(TWISPI1, TWIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
 
+impl_pwm!(PWM0, PWM0, PWM0);
+impl_pwm!(PWM1, PWM1, PWM1);
+impl_pwm!(PWM2, PWM2, PWM2);
+impl_pwm!(PWM3, PWM3, PWM3);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52840.rs b/embassy-nrf/src/chips/nrf52840.rs
index 06b508d89..0b6c3f68e 100644
--- a/embassy-nrf/src/chips/nrf52840.rs
+++ b/embassy-nrf/src/chips/nrf52840.rs
@@ -25,6 +25,12 @@ embassy_extras::peripherals! {
     // SAADC
     SAADC,
 
+    // PWM
+    PWM0,
+    PWM1,
+    PWM2,
+    PWM3,
+
     // TIMER
     TIMER0,
     TIMER1,
@@ -147,6 +153,11 @@ impl_spim!(SPI3, SPIM3, SPIM3);
 impl_twim!(TWISPI0, TWIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
 impl_twim!(TWISPI1, TWIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
 
+impl_pwm!(PWM0, PWM0, PWM0);
+impl_pwm!(PWM1, PWM1, PWM1);
+impl_pwm!(PWM2, PWM2, PWM2);
+impl_pwm!(PWM3, PWM3, PWM3);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/lib.rs b/embassy-nrf/src/lib.rs
index 6ab9cbb27..1c496be19 100644
--- a/embassy-nrf/src/lib.rs
+++ b/embassy-nrf/src/lib.rs
@@ -29,6 +29,8 @@ pub mod buffered_uarte;
 pub mod gpio;
 pub mod gpiote;
 pub mod ppi;
+#[cfg(not(any(feature = "nrf52805", feature = "nrf52820")))]
+pub mod pwm;
 #[cfg(feature = "nrf52840")]
 pub mod qspi;
 pub mod rtc;
diff --git a/embassy-nrf/src/pwm.rs b/embassy-nrf/src/pwm.rs
new file mode 100644
index 000000000..b79c4bc37
--- /dev/null
+++ b/embassy-nrf/src/pwm.rs
@@ -0,0 +1,219 @@
+#![macro_use]
+
+use core::cell::UnsafeCell;
+use core::marker::PhantomData;
+use core::sync::atomic::{compiler_fence, Ordering};
+use embassy::util::Unborrow;
+use embassy_extras::unborrow;
+
+use crate::fmt::{assert, panic, unreachable, *};
+use crate::gpio::sealed::Pin as _;
+use crate::gpio::OptionalPin as GpioOptionalPin;
+use crate::interrupt::Interrupt;
+use crate::pac;
+
+#[derive(Debug, Eq, PartialEq, Clone, Copy)]
+pub enum Prescaler {
+    Div1,
+    Div2,
+    Div4,
+    Div8,
+    Div16,
+    Div32,
+    Div64,
+    Div128,
+}
+
+/// Interface to the UARTE peripheral
+pub struct Pwm<'d, T: Instance> {
+    peri: T,
+    phantom: PhantomData<&'d mut T>,
+}
+
+impl<'d, T: Instance> Pwm<'d, T> {
+    /// Creates the interface to a UARTE instance.
+    /// Sets the baud rate, parity and assigns the pins to the UARTE peripheral.
+    ///
+    /// # Safety
+    ///
+    /// The returned API is safe unless you use `mem::forget` (or similar safe mechanisms)
+    /// on stack allocated buffers which which have been passed to [`send()`](Pwm::send)
+    /// or [`receive`](Pwm::receive).
+    #[allow(unused_unsafe)]
+    pub fn new(
+        pwm: impl Unborrow<Target = T> + 'd,
+        ch0: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
+        ch1: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
+        ch2: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
+        ch3: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
+    ) -> Self {
+        unborrow!(pwm, ch0, ch1, ch2, ch3);
+
+        let r = T::regs();
+        let s = T::state();
+
+        if let Some(pin) = ch0.pin_mut() {
+            pin.set_high();
+            pin.conf().write(|w| w.dir().output());
+        }
+        if let Some(pin) = ch1.pin_mut() {
+            pin.set_high();
+            pin.conf().write(|w| w.dir().output());
+        }
+        if let Some(pin) = ch2.pin_mut() {
+            pin.set_high();
+            pin.conf().write(|w| w.dir().output());
+        }
+        if let Some(pin) = ch3.pin_mut() {
+            pin.set_high();
+            pin.conf().write(|w| w.dir().output());
+        }
+        r.psel.out[0].write(|w| unsafe { w.bits(ch0.psel_bits()) });
+        r.psel.out[1].write(|w| unsafe { w.bits(ch1.psel_bits()) });
+        r.psel.out[2].write(|w| unsafe { w.bits(ch2.psel_bits()) });
+        r.psel.out[3].write(|w| unsafe { w.bits(ch3.psel_bits()) });
+
+        // Disable all interrupts
+        r.intenclr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
+
+        // Enable
+        r.enable.write(|w| w.enable().enabled());
+
+        r.seq0
+            .ptr
+            .write(|w| unsafe { w.bits(&s.duty as *const _ as u32) });
+        r.seq0.cnt.write(|w| unsafe { w.bits(4) });
+        r.seq0.refresh.write(|w| unsafe { w.bits(32) });
+        r.seq0.enddelay.write(|w| unsafe { w.bits(0) });
+
+        r.decoder.write(|w| {
+            w.load().individual();
+            w.mode().refresh_count()
+        });
+        r.mode.write(|w| w.updown().up());
+        r.prescaler.write(|w| w.prescaler().div_1());
+        r.countertop
+            .write(|w| unsafe { w.countertop().bits(32767) });
+        r.loop_.write(|w| w.cnt().disabled());
+
+        Self {
+            peri: pwm,
+            phantom: PhantomData,
+        }
+    }
+
+    /// Sets duty cycle (15 bit) for a PWM channel.
+    pub fn set_duty(&self, channel: usize, duty: u16) {
+        let s = T::state();
+        unsafe { (*s.duty.get())[channel] = duty & 0x7FFF };
+
+        compiler_fence(Ordering::SeqCst);
+        T::regs().tasks_seqstart[0].write(|w| unsafe { w.bits(1) });
+    }
+
+    /// Sets the PWM clock prescaler.
+    #[inline(always)]
+    pub fn set_prescaler(&self, div: Prescaler) {
+        T::regs().prescaler.write(|w| w.prescaler().bits(div as u8));
+    }
+
+    /// Sets the PWM clock prescaler.
+    #[inline(always)]
+    pub fn prescaler(&self) -> Prescaler {
+        match T::regs().prescaler.read().prescaler().bits() {
+            0 => Prescaler::Div1,
+            1 => Prescaler::Div2,
+            2 => Prescaler::Div4,
+            3 => Prescaler::Div8,
+            4 => Prescaler::Div16,
+            5 => Prescaler::Div32,
+            6 => Prescaler::Div64,
+            7 => Prescaler::Div128,
+            _ => unreachable!(),
+        }
+    }
+
+    /// Sets the maximum duty cycle value.
+    #[inline(always)]
+    pub fn set_max_duty(&self, duty: u16) {
+        T::regs()
+            .countertop
+            .write(|w| unsafe { w.countertop().bits(duty.min(32767u16)) });
+    }
+
+    /// Returns the maximum duty cycle value.
+    #[inline(always)]
+    pub fn max_duty(&self) -> u16 {
+        T::regs().countertop.read().countertop().bits()
+    }
+
+    /// Sets the PWM output frequency.
+    #[inline(always)]
+    pub fn set_period(&self, freq: u32) {
+        let clk = 16_000_000u32 >> (self.prescaler() as u8);
+        let duty = clk / freq;
+        self.set_max_duty(duty.min(32767) as u16);
+    }
+
+    /// Returns the PWM output frequency.
+    #[inline(always)]
+    pub fn period(&self) -> u32 {
+        let clk = 16_000_000u32 >> (self.prescaler() as u8);
+        let max_duty = self.max_duty() as u32;
+        clk / max_duty
+    }
+}
+
+impl<'a, T: Instance> Drop for Pwm<'a, T> {
+    fn drop(&mut self) {
+        let r = T::regs();
+        r.enable.write(|w| w.enable().disabled());
+
+        info!("pwm drop: done");
+
+        // TODO: disable pins
+    }
+}
+
+pub(crate) mod sealed {
+    use super::*;
+
+    pub struct State {
+        pub duty: UnsafeCell<[u16; 4]>,
+    }
+    unsafe impl Sync for State {}
+
+    impl State {
+        pub const fn new() -> Self {
+            Self {
+                duty: UnsafeCell::new([0; 4]),
+            }
+        }
+    }
+
+    pub trait Instance {
+        fn regs() -> &'static pac::pwm0::RegisterBlock;
+        fn state() -> &'static State;
+    }
+}
+
+pub trait Instance: sealed::Instance + 'static {
+    type Interrupt: Interrupt;
+}
+
+macro_rules! impl_pwm {
+    ($type:ident, $pac_type:ident, $irq:ident) => {
+        impl crate::pwm::sealed::Instance for peripherals::$type {
+            fn regs() -> &'static pac::pwm0::RegisterBlock {
+                unsafe { &*pac::$pac_type::ptr() }
+            }
+            fn state() -> &'static crate::pwm::sealed::State {
+                static STATE: crate::pwm::sealed::State = crate::pwm::sealed::State::new();
+                &STATE
+            }
+        }
+        impl crate::pwm::Instance for peripherals::$type {
+            type Interrupt = crate::interrupt::$irq;
+        }
+    };
+}