From 4410aacafb2141c1c0838598d11581e24aab3b0f Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Fri, 19 Jan 2024 23:13:46 +0100
Subject: [PATCH 01/27] feat: add basic support for nRF51 chips to embassy-nrf

---
 embassy-nrf/Cargo.toml            |   8 ++
 embassy-nrf/src/chips/nrf51.rs    | 168 ++++++++++++++++++++++++++++++
 embassy-nrf/src/gpio.rs           |  12 +++
 embassy-nrf/src/lib.rs            |  19 +++-
 embassy-nrf/src/ppi/ppi.rs        |   1 +
 embassy-nrf/src/rng.rs            |   2 +-
 embassy-nrf/src/time_driver.rs    |   2 +-
 embassy-nrf/src/timer.rs          |  16 ++-
 examples/nrf51/.cargo/config.toml |   9 ++
 examples/nrf51/Cargo.toml         |  20 ++++
 examples/nrf51/build.rs           |  35 +++++++
 examples/nrf51/memory.x           |   5 +
 examples/nrf51/src/bin/blinky.rs  |  21 ++++
 13 files changed, 311 insertions(+), 7 deletions(-)
 create mode 100644 embassy-nrf/src/chips/nrf51.rs
 create mode 100644 examples/nrf51/.cargo/config.toml
 create mode 100644 examples/nrf51/Cargo.toml
 create mode 100644 examples/nrf51/build.rs
 create mode 100644 examples/nrf51/memory.x
 create mode 100644 examples/nrf51/src/bin/blinky.rs

diff --git a/embassy-nrf/Cargo.toml b/embassy-nrf/Cargo.toml
index 10f268b51..529a56c46 100644
--- a/embassy-nrf/Cargo.toml
+++ b/embassy-nrf/Cargo.toml
@@ -15,6 +15,7 @@ src_base_git = "https://github.com/embassy-rs/embassy/blob/$COMMIT/embassy-nrf/s
 
 features = ["time", "defmt", "unstable-pac", "gpiote", "time-driver-rtc1"]
 flavors = [
+    { regex_feature = "nrf51", target = "thumbv6m-none-eabi" },
     { regex_feature = "nrf52.*", target = "thumbv7em-none-eabihf" },
     { regex_feature = "nrf53.*", target = "thumbv8m.main-none-eabihf" },
     { regex_feature = "nrf91.*", target = "thumbv8m.main-none-eabihf" },
@@ -28,6 +29,7 @@ rustdoc-args = ["--cfg", "docsrs"]
 default = ["rt"]
 ## Cortex-M runtime (enabled by default)
 rt = [
+    "nrf51-pac?/rt",
     "nrf52805-pac?/rt",
     "nrf52810-pac?/rt",
     "nrf52811-pac?/rt",
@@ -71,6 +73,8 @@ reset-pin-as-gpio = []
 qspi-multiwrite-flash = []
 
 #! ### Chip selection features
+## nRF51
+nrf51 = ["nrf51-pac", "_nrf51", "portable-atomic/unsafe-assume-single-core"]
 ## nRF52805
 nrf52805 = ["nrf52805-pac", "_nrf52"]
 ## nRF52810
@@ -104,6 +108,7 @@ _nrf5340-net = ["_nrf5340", "nrf5340-net-pac"]
 _nrf5340 = ["_gpio-p1", "_dppi"]
 _nrf9160 = ["nrf9160-pac", "_dppi"]
 _nrf52 = ["_ppi"]
+_nrf51 = ["_ppi"]
 
 _time-driver = ["dep:embassy-time-driver", "embassy-time-driver?/tick-hz-32_768"]
 
@@ -132,6 +137,8 @@ embedded-hal-async = { version = "1.0" }
 embedded-io = { version = "0.6.0" }
 embedded-io-async = { version = "0.6.1" }
 
+portable-atomic = { version = "1", default-features = false, features = ["require-cas"] }
+
 defmt = { version = "0.3", optional = true }
 log = { version = "0.4.14", optional = true }
 cortex-m-rt = ">=0.6.15,<0.8"
@@ -144,6 +151,7 @@ embedded-storage-async = "0.4.0"
 cfg-if = "1.0.0"
 document-features = "0.2.7"
 
+nrf51-pac = { version = "0.12.0", optional = true }
 nrf52805-pac = { version = "0.12.0", optional = true }
 nrf52810-pac = { version = "0.12.0", optional = true }
 nrf52811-pac = { version = "0.12.0", optional = true }
diff --git a/embassy-nrf/src/chips/nrf51.rs b/embassy-nrf/src/chips/nrf51.rs
new file mode 100644
index 000000000..f5db4b847
--- /dev/null
+++ b/embassy-nrf/src/chips/nrf51.rs
@@ -0,0 +1,168 @@
+pub use nrf51_pac as pac;
+
+/// The maximum buffer size that the EasyDMA can send/recv in one operation.
+pub const EASY_DMA_SIZE: usize = (1 << 14) - 1;
+pub const FORCE_COPY_BUFFER_SIZE: usize = 256;
+
+pub const FLASH_SIZE: usize = 128 * 1024;
+
+embassy_hal_internal::peripherals! {
+    // RTC
+    RTC0,
+    RTC1,
+
+    // WDT
+    WDT,
+
+    // NVMC
+    NVMC,
+
+    // RNG
+    RNG,
+
+    // UARTE
+    UART0,
+
+    // SPI/TWI
+    TWI0,
+    SPI0,
+
+    // ADC
+    ADC,
+
+    // TIMER
+    TIMER0,
+    TIMER1,
+    TIMER2,
+
+    // GPIOTE
+    GPIOTE_CH0,
+    GPIOTE_CH1,
+    GPIOTE_CH2,
+    GPIOTE_CH3,
+
+    // PPI
+    PPI_CH0,
+    PPI_CH1,
+    PPI_CH2,
+    PPI_CH3,
+    PPI_CH4,
+    PPI_CH5,
+    PPI_CH6,
+    PPI_CH7,
+    PPI_CH8,
+    PPI_CH9,
+    PPI_CH10,
+    PPI_CH11,
+    PPI_CH12,
+    PPI_CH13,
+    PPI_CH14,
+    PPI_CH15,
+
+    PPI_GROUP0,
+    PPI_GROUP1,
+    PPI_GROUP2,
+    PPI_GROUP3,
+
+    // GPIO port 0
+    P0_00,
+    P0_01,
+    P0_02,
+    P0_03,
+    P0_04,
+    P0_05,
+    P0_06,
+    P0_07,
+    P0_08,
+    P0_09,
+    P0_10,
+    P0_11,
+    P0_12,
+    P0_13,
+    P0_14,
+    P0_15,
+    P0_16,
+    P0_17,
+    P0_18,
+    P0_19,
+    P0_20,
+    P0_21,
+    P0_22,
+    P0_23,
+    P0_24,
+    P0_25,
+    P0_26,
+    P0_27,
+    P0_28,
+    P0_29,
+    P0_30,
+    P0_31,
+
+    // TEMP
+    TEMP,
+}
+
+// impl_timer!(TIMER0, TIMER0, TIMER0);
+// impl_timer!(TIMER1, TIMER1, TIMER1);
+// impl_timer!(TIMER2, TIMER2, TIMER2);
+
+impl_pin!(P0_00, 0, 0);
+impl_pin!(P0_01, 0, 1);
+impl_pin!(P0_02, 0, 2);
+impl_pin!(P0_03, 0, 3);
+impl_pin!(P0_04, 0, 4);
+impl_pin!(P0_05, 0, 5);
+impl_pin!(P0_06, 0, 6);
+impl_pin!(P0_07, 0, 7);
+impl_pin!(P0_08, 0, 8);
+impl_pin!(P0_09, 0, 9);
+impl_pin!(P0_10, 0, 10);
+impl_pin!(P0_11, 0, 11);
+impl_pin!(P0_12, 0, 12);
+impl_pin!(P0_13, 0, 13);
+impl_pin!(P0_14, 0, 14);
+impl_pin!(P0_15, 0, 15);
+impl_pin!(P0_16, 0, 16);
+impl_pin!(P0_17, 0, 17);
+impl_pin!(P0_18, 0, 18);
+impl_pin!(P0_19, 0, 19);
+impl_pin!(P0_20, 0, 20);
+impl_pin!(P0_21, 0, 21);
+impl_pin!(P0_22, 0, 22);
+impl_pin!(P0_23, 0, 23);
+impl_pin!(P0_24, 0, 24);
+impl_pin!(P0_25, 0, 25);
+impl_pin!(P0_26, 0, 26);
+impl_pin!(P0_27, 0, 27);
+impl_pin!(P0_28, 0, 28);
+impl_pin!(P0_29, 0, 29);
+impl_pin!(P0_30, 0, 30);
+impl_pin!(P0_31, 0, 31);
+
+embassy_hal_internal::interrupt_mod!(
+    POWER_CLOCK,
+    RADIO,
+    UART0,
+    SPI0_TWI0,
+    SPI1_TWI1,
+    GPIOTE,
+    ADC,
+    TIMER0,
+    TIMER1,
+    TIMER2,
+    RTC0,
+    TEMP,
+    RNG,
+    ECB,
+    CCM_AAR,
+    WDT,
+    RTC1,
+    QDEC,
+    LPCOMP,
+    SWI0,
+    SWI1,
+    SWI2,
+    SWI3,
+    SWI4,
+    SWI5,
+);
diff --git a/embassy-nrf/src/gpio.rs b/embassy-nrf/src/gpio.rs
index 287811e61..164363460 100644
--- a/embassy-nrf/src/gpio.rs
+++ b/embassy-nrf/src/gpio.rs
@@ -8,8 +8,17 @@ use cfg_if::cfg_if;
 use embassy_hal_internal::{impl_peripheral, into_ref, PeripheralRef};
 
 use self::sealed::Pin as _;
+
+#[cfg(not(feature = "nrf51"))]
 use crate::pac::p0 as gpio;
+#[cfg(not(feature = "nrf51"))]
 use crate::pac::p0::pin_cnf::{DRIVE_A, PULL_A};
+
+#[cfg(feature = "nrf51")]
+use crate::pac::gpio;
+#[cfg(feature = "nrf51")]
+use crate::pac::gpio::pin_cnf::{DRIVE_A, PULL_A};
+
 use crate::{pac, Peripheral};
 
 /// A GPIO port with up to 32 pins.
@@ -376,6 +385,9 @@ pub(crate) mod sealed {
         fn block(&self) -> &gpio::RegisterBlock {
             unsafe {
                 match self.pin_port() / 32 {
+                    #[cfg(feature = "nrf51")]
+                    0 => &*pac::GPIO::ptr(),
+                    #[cfg(not(feature = "nrf51"))]
                     0 => &*pac::P0::ptr(),
                     #[cfg(feature = "_gpio-p1")]
                     1 => &*pac::P1::ptr(),
diff --git a/embassy-nrf/src/lib.rs b/embassy-nrf/src/lib.rs
index d9c92a76d..923e48ec2 100644
--- a/embassy-nrf/src/lib.rs
+++ b/embassy-nrf/src/lib.rs
@@ -40,6 +40,7 @@ pub(crate) mod util;
 #[cfg(feature = "_time-driver")]
 mod time_driver;
 
+#[cfg(not(feature = "nrf51"))]
 pub mod buffered_uarte;
 pub mod gpio;
 #[cfg(feature = "gpiote")]
@@ -58,7 +59,12 @@ pub mod nvmc;
 ))]
 pub mod pdm;
 pub mod ppi;
-#[cfg(not(any(feature = "nrf52805", feature = "nrf52820", feature = "_nrf5340-net")))]
+#[cfg(not(any(
+    feature = "nrf51",
+    feature = "nrf52805",
+    feature = "nrf52820",
+    feature = "_nrf5340-net"
+)))]
 pub mod pwm;
 #[cfg(not(any(feature = "nrf51", feature = "_nrf9160", feature = "_nrf5340-net")))]
 pub mod qdec;
@@ -66,15 +72,20 @@ pub mod qdec;
 pub mod qspi;
 #[cfg(not(any(feature = "_nrf5340-app", feature = "_nrf9160")))]
 pub mod rng;
-#[cfg(not(any(feature = "nrf52820", feature = "_nrf5340-net")))]
+#[cfg(not(any(feature = "nrf51", feature = "nrf52820", feature = "_nrf5340-net")))]
 pub mod saadc;
+#[cfg(not(feature = "nrf51"))]
 pub mod spim;
+#[cfg(not(feature = "nrf51"))]
 pub mod spis;
 #[cfg(not(any(feature = "_nrf5340", feature = "_nrf9160")))]
 pub mod temp;
 pub mod timer;
+#[cfg(not(feature = "nrf51"))]
 pub mod twim;
+#[cfg(not(feature = "nrf51"))]
 pub mod twis;
+#[cfg(not(feature = "nrf51"))]
 pub mod uarte;
 #[cfg(any(
     feature = "_nrf5340-app",
@@ -87,6 +98,7 @@ pub mod usb;
 pub mod wdt;
 
 // This mod MUST go last, so that it sees all the `impl_foo!` macros
+#[cfg_attr(feature = "nrf51", path = "chips/nrf51.rs")]
 #[cfg_attr(feature = "nrf52805", path = "chips/nrf52805.rs")]
 #[cfg_attr(feature = "nrf52810", path = "chips/nrf52810.rs")]
 #[cfg_attr(feature = "nrf52811", path = "chips/nrf52811.rs")]
@@ -374,6 +386,7 @@ pub fn init(config: config::Config) -> Peripherals {
     let mut needs_reset = false;
 
     // Setup debug protection.
+    #[cfg(not(feature = "nrf51"))]
     match config.debug {
         config::Debug::Allowed => {
             #[cfg(feature = "_nrf52")]
@@ -489,7 +502,7 @@ pub fn init(config: config::Config) -> Peripherals {
     }
 
     // Configure LFCLK.
-    #[cfg(not(any(feature = "_nrf5340", feature = "_nrf9160")))]
+    #[cfg(not(any(feature = "nrf51", feature = "_nrf5340", feature = "_nrf9160")))]
     match config.lfclk_source {
         config::LfclkSource::InternalRC => r.lfclksrc.write(|w| w.src().rc()),
         config::LfclkSource::Synthesized => r.lfclksrc.write(|w| w.src().synth()),
diff --git a/embassy-nrf/src/ppi/ppi.rs b/embassy-nrf/src/ppi/ppi.rs
index 3e9e9fc81..4a12764ad 100644
--- a/embassy-nrf/src/ppi/ppi.rs
+++ b/embassy-nrf/src/ppi/ppi.rs
@@ -84,6 +84,7 @@ impl<'d, C: Channel, const EVENT_COUNT: usize, const TASK_COUNT: usize> Drop for
         let n = self.ch.number();
         r.ch[n].eep.write(|w| unsafe { w.bits(0) });
         r.ch[n].tep.write(|w| unsafe { w.bits(0) });
+        #[cfg(not(feature = "nrf51"))]
         r.fork[n].tep.write(|w| unsafe { w.bits(0) });
     }
 }
diff --git a/embassy-nrf/src/rng.rs b/embassy-nrf/src/rng.rs
index e2803f0d3..7f2e76a55 100644
--- a/embassy-nrf/src/rng.rs
+++ b/embassy-nrf/src/rng.rs
@@ -5,7 +5,7 @@
 use core::future::poll_fn;
 use core::marker::PhantomData;
 use core::ptr;
-use core::sync::atomic::{AtomicPtr, Ordering};
+use portable_atomic::{AtomicPtr, Ordering};
 use core::task::Poll;
 
 use embassy_hal_internal::drop::OnDrop;
diff --git a/embassy-nrf/src/time_driver.rs b/embassy-nrf/src/time_driver.rs
index 042f7c5f7..855d133df 100644
--- a/embassy-nrf/src/time_driver.rs
+++ b/embassy-nrf/src/time_driver.rs
@@ -1,6 +1,6 @@
 use core::cell::Cell;
-use core::sync::atomic::{compiler_fence, AtomicU32, AtomicU8, Ordering};
 use core::{mem, ptr};
+use portable_atomic::{compiler_fence, AtomicU32, AtomicU8, Ordering};
 
 use critical_section::CriticalSection;
 use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
diff --git a/embassy-nrf/src/timer.rs b/embassy-nrf/src/timer.rs
index 3dbfdac42..272fffc0a 100644
--- a/embassy-nrf/src/timer.rs
+++ b/embassy-nrf/src/timer.rs
@@ -122,12 +122,16 @@ impl<'d, T: Instance> Timer<'d, T> {
         // since changing BITMODE while running can cause 'unpredictable behaviour' according to the specification.
         this.stop();
 
+        #[cfg(not(feature = "nrf51"))]
         if is_counter {
             regs.mode.write(|w| w.mode().low_power_counter());
         } else {
             regs.mode.write(|w| w.mode().timer());
         }
 
+        #[cfg(feature = "nrf51")]
+        regs.mode.write(|w| w.mode().timer());
+
         // Make the counter's max value as high as possible.
         // TODO: is there a reason someone would want to set this lower?
         regs.bitmode.write(|w| w.bitmode()._32bit());
@@ -238,7 +242,11 @@ pub struct Cc<'d, T: Instance> {
 impl<'d, T: Instance> Cc<'d, T> {
     /// Get the current value stored in the register.
     pub fn read(&self) -> u32 {
-        T::regs().cc[self.n].read().cc().bits()
+        #[cfg(not(feature = "nrf51"))]
+        return T::regs().cc[self.n].read().cc().bits();
+
+        #[cfg(feature = "nrf51")]
+        return T::regs().cc[self.n].read().bits();
     }
 
     /// Set the value stored in the register.
@@ -246,7 +254,11 @@ impl<'d, T: Instance> Cc<'d, T> {
     /// `event_compare` will fire when the timer's counter reaches this value.
     pub fn write(&self, value: u32) {
         // SAFETY: there are no invalid values for the CC register.
-        T::regs().cc[self.n].write(|w| unsafe { w.cc().bits(value) })
+        #[cfg(not(feature = "nrf51"))]
+        T::regs().cc[self.n].write(|w| unsafe { w.cc().bits(value) });
+
+        #[cfg(feature = "nrf51")]
+        T::regs().cc[self.n].write(|w| unsafe { w.bits(value) });
     }
 
     /// Capture the current value of the timer's counter in this register, and return it.
diff --git a/examples/nrf51/.cargo/config.toml b/examples/nrf51/.cargo/config.toml
new file mode 100644
index 000000000..84f0e1572
--- /dev/null
+++ b/examples/nrf51/.cargo/config.toml
@@ -0,0 +1,9 @@
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+# replace nRF82840_xxAA with your chip as listed in `probe-rs chip list`
+runner = "probe-rs run --chip nRF51822_xxAA"
+
+[build]
+target = "thumbv6m-none-eabi"
+
+[env]
+DEFMT_LOG = "trace"
diff --git a/examples/nrf51/Cargo.toml b/examples/nrf51/Cargo.toml
new file mode 100644
index 000000000..8507c415c
--- /dev/null
+++ b/examples/nrf51/Cargo.toml
@@ -0,0 +1,20 @@
+[package]
+edition = "2021"
+name = "embassy-nrf51-examples"
+version = "0.1.0"
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["task-arena-size-8192", "arch-cortex-m", "executor-thread", "executor-interrupt", "defmt", "integrated-timers"] }
+embassy-time = { version = "0.3.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime"] }
+embassy-nrf = { version = "0.1.0", path = "../../embassy-nrf", features = ["defmt", "nrf51", "time-driver-rtc1", "unstable-pac", "time", "rt"] }
+
+defmt = "0.3"
+defmt-rtt = "0.4"
+
+cortex-m = { version = "0.7.6", features = ["inline-asm", "critical-section-single-core"] }
+cortex-m-rt = "0.7"
+panic-probe = { version = "0.3", features = ["print-defmt"] }
+
+[profile.release]
+debug = 2
diff --git a/examples/nrf51/build.rs b/examples/nrf51/build.rs
new file mode 100644
index 000000000..30691aa97
--- /dev/null
+++ b/examples/nrf51/build.rs
@@ -0,0 +1,35 @@
+//! This build script copies the `memory.x` file from the crate root into
+//! a directory where the linker can always find it at build time.
+//! For many projects this is optional, as the linker always searches the
+//! project root directory -- wherever `Cargo.toml` is. However, if you
+//! are using a workspace or have a more complicated build setup, this
+//! build script becomes required. Additionally, by requesting that
+//! Cargo re-run the build script whenever `memory.x` is changed,
+//! updating `memory.x` ensures a rebuild of the application with the
+//! new memory settings.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+    println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+}
diff --git a/examples/nrf51/memory.x b/examples/nrf51/memory.x
new file mode 100644
index 000000000..ad5f80292
--- /dev/null
+++ b/examples/nrf51/memory.x
@@ -0,0 +1,5 @@
+MEMORY
+{
+  FLASH                    : ORIGIN = 0x00000000, LENGTH = 256K
+  RAM                      : ORIGIN = 0x20000000, LENGTH = 32K
+}
diff --git a/examples/nrf51/src/bin/blinky.rs b/examples/nrf51/src/bin/blinky.rs
new file mode 100644
index 000000000..ff686c6ae
--- /dev/null
+++ b/examples/nrf51/src/bin/blinky.rs
@@ -0,0 +1,21 @@
+#![no_std]
+#![no_main]
+
+use embassy_executor::Spawner;
+use embassy_nrf::gpio::{Level, Output, OutputDrive};
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+
+    let p = embassy_nrf::init(Default::default());
+    let mut led = Output::new(p.P0_21, Level::Low, OutputDrive::Standard);
+
+    loop {
+        led.set_high();
+        Timer::after_millis(300).await;
+        led.set_low();
+        Timer::after_millis(300).await;
+    }
+}

From 2a810a1a6ad5351ef2248133855dc01ba4b7a76b Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Sat, 20 Jan 2024 16:23:12 +0100
Subject: [PATCH 02/27] rustfmt

---
 embassy-nrf/src/rng.rs           | 2 +-
 examples/nrf51/src/bin/blinky.rs | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/embassy-nrf/src/rng.rs b/embassy-nrf/src/rng.rs
index 7f2e76a55..79088b25d 100644
--- a/embassy-nrf/src/rng.rs
+++ b/embassy-nrf/src/rng.rs
@@ -5,8 +5,8 @@
 use core::future::poll_fn;
 use core::marker::PhantomData;
 use core::ptr;
-use portable_atomic::{AtomicPtr, Ordering};
 use core::task::Poll;
+use portable_atomic::{AtomicPtr, Ordering};
 
 use embassy_hal_internal::drop::OnDrop;
 use embassy_hal_internal::{into_ref, PeripheralRef};
diff --git a/examples/nrf51/src/bin/blinky.rs b/examples/nrf51/src/bin/blinky.rs
index ff686c6ae..7c12ffcbc 100644
--- a/examples/nrf51/src/bin/blinky.rs
+++ b/examples/nrf51/src/bin/blinky.rs
@@ -8,7 +8,6 @@ use {defmt_rtt as _, panic_probe as _};
 
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {
-
     let p = embassy_nrf::init(Default::default());
     let mut led = Output::new(p.P0_21, Level::Low, OutputDrive::Standard);
 

From 53ea850d289384ea1810419b980ad73bcd556a04 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Sat, 20 Jan 2024 16:24:02 +0100
Subject: [PATCH 03/27]  rustfmt again

---
 embassy-nrf/src/gpio.rs        | 11 ++++-------
 embassy-nrf/src/rng.rs         |  2 +-
 embassy-nrf/src/time_driver.rs |  2 +-
 3 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/embassy-nrf/src/gpio.rs b/embassy-nrf/src/gpio.rs
index 164363460..b1eb8ae87 100644
--- a/embassy-nrf/src/gpio.rs
+++ b/embassy-nrf/src/gpio.rs
@@ -8,17 +8,14 @@ use cfg_if::cfg_if;
 use embassy_hal_internal::{impl_peripheral, into_ref, PeripheralRef};
 
 use self::sealed::Pin as _;
-
-#[cfg(not(feature = "nrf51"))]
-use crate::pac::p0 as gpio;
-#[cfg(not(feature = "nrf51"))]
-use crate::pac::p0::pin_cnf::{DRIVE_A, PULL_A};
-
 #[cfg(feature = "nrf51")]
 use crate::pac::gpio;
 #[cfg(feature = "nrf51")]
 use crate::pac::gpio::pin_cnf::{DRIVE_A, PULL_A};
-
+#[cfg(not(feature = "nrf51"))]
+use crate::pac::p0 as gpio;
+#[cfg(not(feature = "nrf51"))]
+use crate::pac::p0::pin_cnf::{DRIVE_A, PULL_A};
 use crate::{pac, Peripheral};
 
 /// A GPIO port with up to 32 pins.
diff --git a/embassy-nrf/src/rng.rs b/embassy-nrf/src/rng.rs
index 79088b25d..966097578 100644
--- a/embassy-nrf/src/rng.rs
+++ b/embassy-nrf/src/rng.rs
@@ -6,11 +6,11 @@ use core::future::poll_fn;
 use core::marker::PhantomData;
 use core::ptr;
 use core::task::Poll;
-use portable_atomic::{AtomicPtr, Ordering};
 
 use embassy_hal_internal::drop::OnDrop;
 use embassy_hal_internal::{into_ref, PeripheralRef};
 use embassy_sync::waitqueue::AtomicWaker;
+use portable_atomic::{AtomicPtr, Ordering};
 
 use crate::interrupt::typelevel::Interrupt;
 use crate::{interrupt, Peripheral};
diff --git a/embassy-nrf/src/time_driver.rs b/embassy-nrf/src/time_driver.rs
index 855d133df..0f31c5c9c 100644
--- a/embassy-nrf/src/time_driver.rs
+++ b/embassy-nrf/src/time_driver.rs
@@ -1,11 +1,11 @@
 use core::cell::Cell;
 use core::{mem, ptr};
-use portable_atomic::{compiler_fence, AtomicU32, AtomicU8, Ordering};
 
 use critical_section::CriticalSection;
 use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
 use embassy_sync::blocking_mutex::CriticalSectionMutex as Mutex;
 use embassy_time_driver::{AlarmHandle, Driver};
+use portable_atomic::{compiler_fence, AtomicU32, AtomicU8, Ordering};
 
 use crate::interrupt::InterruptExt;
 use crate::{interrupt, pac};

From 25f82538aed809c17264bab8cddad30004fb60cf Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Sat, 20 Jan 2024 20:56:24 +0100
Subject: [PATCH 04/27] fix doc comment

---
 examples/nrf51/.cargo/config.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/nrf51/.cargo/config.toml b/examples/nrf51/.cargo/config.toml
index 84f0e1572..29d35a9b4 100644
--- a/examples/nrf51/.cargo/config.toml
+++ b/examples/nrf51/.cargo/config.toml
@@ -1,5 +1,5 @@
 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
-# replace nRF82840_xxAA with your chip as listed in `probe-rs chip list`
+# replace nRF51822_xxAA with your chip as listed in `probe-rs chip list`
 runner = "probe-rs run --chip nRF51822_xxAA"
 
 [build]

From 6126183db852fbf4187d4a5516cc8bd6d3697443 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Tue, 23 Jan 2024 23:16:06 +0100
Subject: [PATCH 05/27] fix: remove portable-atomic from rng

---
 embassy-nrf/src/rng.rs | 127 ++++++++++++++++++++++-------------------
 1 file changed, 67 insertions(+), 60 deletions(-)

diff --git a/embassy-nrf/src/rng.rs b/embassy-nrf/src/rng.rs
index 966097578..6145dd14f 100644
--- a/embassy-nrf/src/rng.rs
+++ b/embassy-nrf/src/rng.rs
@@ -9,8 +9,6 @@ use core::task::Poll;
 
 use embassy_hal_internal::drop::OnDrop;
 use embassy_hal_internal::{into_ref, PeripheralRef};
-use embassy_sync::waitqueue::AtomicWaker;
-use portable_atomic::{AtomicPtr, Ordering};
 
 use crate::interrupt::typelevel::Interrupt;
 use crate::{interrupt, Peripheral};
@@ -22,7 +20,6 @@ pub struct InterruptHandler<T: Instance> {
 
 impl<T: Instance> interrupt::typelevel::Handler<T::Interrupt> for InterruptHandler<T> {
     unsafe fn on_interrupt() {
-        let s = T::state();
         let r = T::regs();
 
         // Clear the event.
@@ -30,46 +27,26 @@ impl<T: Instance> interrupt::typelevel::Handler<T::Interrupt> for InterruptHandl
 
         // Mutate the slice within a critical section,
         // so that the future isn't dropped in between us loading the pointer and actually dereferencing it.
-        let (ptr, end) = critical_section::with(|_| {
-            let ptr = s.ptr.load(Ordering::Relaxed);
+        critical_section::with(|cs| {
+            let mut state = T::state().borrow_mut(cs);
             // We need to make sure we haven't already filled the whole slice,
             // in case the interrupt fired again before the executor got back to the future.
-            let end = s.end.load(Ordering::Relaxed);
-            if !ptr.is_null() && ptr != end {
+            if !state.ptr.is_null() && state.ptr != state.end {
                 // If the future was dropped, the pointer would have been set to null,
                 // so we're still good to mutate the slice.
                 // The safety contract of `Rng::new` means that the future can't have been dropped
                 // without calling its destructor.
                 unsafe {
-                    *ptr = r.value.read().value().bits();
+                    *state.ptr = r.value.read().value().bits();
+                    state.ptr = state.ptr.add(1);
                 }
+
+                if state.ptr == state.end {
+                    state.waker.wake();
+                }
+
             }
-            (ptr, end)
         });
-
-        if ptr.is_null() || ptr == end {
-            // If the future was dropped, there's nothing to do.
-            // If `ptr == end`, we were called by mistake, so return.
-            return;
-        }
-
-        let new_ptr = unsafe { ptr.add(1) };
-        match s
-            .ptr
-            .compare_exchange(ptr, new_ptr, Ordering::Relaxed, Ordering::Relaxed)
-        {
-            Ok(_) => {
-                let end = s.end.load(Ordering::Relaxed);
-                // It doesn't matter if `end` was changed under our feet, because then this will just be false.
-                if new_ptr == end {
-                    s.waker.wake();
-                }
-            }
-            Err(_) => {
-                // If the future was dropped or finished, there's no point trying to wake it.
-                // It will have already stopped the RNG, so there's no need to do that either.
-            }
-        }
     }
 }
 
@@ -136,13 +113,15 @@ impl<'d, T: Instance> Rng<'d, T> {
             return; // Nothing to fill
         }
 
-        let s = T::state();
 
         let range = dest.as_mut_ptr_range();
         // Even if we've preempted the interrupt, it can't preempt us again,
         // so we don't need to worry about the order we write these in.
-        s.ptr.store(range.start, Ordering::Relaxed);
-        s.end.store(range.end, Ordering::Relaxed);
+        critical_section::with(|cs| {
+            let mut state = T::state().borrow_mut(cs);
+            state.ptr = range.start;
+            state.end = range.end;
+        });
 
         self.enable_irq();
         self.start();
@@ -151,24 +130,24 @@ impl<'d, T: Instance> Rng<'d, T> {
             self.stop();
             self.disable_irq();
 
-            // The interrupt is now disabled and can't preempt us anymore, so the order doesn't matter here.
-            s.ptr.store(ptr::null_mut(), Ordering::Relaxed);
-            s.end.store(ptr::null_mut(), Ordering::Relaxed);
+            critical_section::with(|cs| {
+                let mut state = T::state().borrow_mut(cs);
+                state.ptr = ptr::null_mut();
+                state.end = ptr::null_mut();
+            });
         });
 
         poll_fn(|cx| {
-            s.waker.register(cx.waker());
-
-            // The interrupt will never modify `end`, so load it first and then get the most up-to-date `ptr`.
-            let end = s.end.load(Ordering::Relaxed);
-            let ptr = s.ptr.load(Ordering::Relaxed);
-
-            if ptr == end {
-                // We're done.
-                Poll::Ready(())
-            } else {
-                Poll::Pending
-            }
+            critical_section::with(|cs| {
+                let mut s = T::state().borrow_mut(cs);
+                s.waker.register(cx.waker());
+                if s.ptr == s.end {
+                    // We're done.
+                    Poll::Ready(())
+                } else {
+                    Poll::Pending
+                }
+            })
         })
         .await;
 
@@ -194,9 +173,11 @@ impl<'d, T: Instance> Rng<'d, T> {
 impl<'d, T: Instance> Drop for Rng<'d, T> {
     fn drop(&mut self) {
         self.stop();
-        let s = T::state();
-        s.ptr.store(ptr::null_mut(), Ordering::Relaxed);
-        s.end.store(ptr::null_mut(), Ordering::Relaxed);
+        critical_section::with(|cs| {
+            let mut state = T::state().borrow_mut(cs);
+            state.ptr = ptr::null_mut();
+            state.end = ptr::null_mut();
+        });
     }
 }
 
@@ -227,21 +208,47 @@ impl<'d, T: Instance> rand_core::RngCore for Rng<'d, T> {
 impl<'d, T: Instance> rand_core::CryptoRng for Rng<'d, T> {}
 
 pub(crate) mod sealed {
+    use core::cell::{Ref, RefMut, RefCell};
+
+    use critical_section::Mutex;
+    use critical_section::CriticalSection;
+    use embassy_sync::waitqueue::WakerRegistration;
+
     use super::*;
 
     /// Peripheral static state
     pub struct State {
-        pub ptr: AtomicPtr<u8>,
-        pub end: AtomicPtr<u8>,
-        pub waker: AtomicWaker,
+        inner: Mutex<RefCell<InnerState>>,
+    }
+
+    pub struct InnerState {
+        pub ptr: *mut u8,
+        pub end: *mut u8,
+        pub waker: WakerRegistration,
     }
 
     impl State {
         pub const fn new() -> Self {
             Self {
-                ptr: AtomicPtr::new(ptr::null_mut()),
-                end: AtomicPtr::new(ptr::null_mut()),
-                waker: AtomicWaker::new(),
+                inner: Mutex::new(RefCell::new(InnerState::new())),
+            }
+        }
+
+        pub fn borrow<'cs>(&'cs self, cs: CriticalSection<'cs>) -> Ref<'cs, InnerState> {
+            self.inner.borrow(cs).borrow()
+        }
+
+        pub fn borrow_mut<'cs>(&'cs self, cs: CriticalSection<'cs>) -> RefMut<'cs, InnerState> {
+            self.inner.borrow(cs).borrow_mut()
+        }
+    }
+
+    impl InnerState {
+        pub const fn new() -> Self {
+            Self {
+                ptr: ptr::null_mut(),
+                end: ptr::null_mut(),
+                waker: WakerRegistration::new(),
             }
         }
     }

From 00d66cce1db71511b1a872a837c2d5dd0c22a598 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Wed, 24 Jan 2024 19:27:55 +0100
Subject: [PATCH 06/27] modify time driver to not require portable-atomic

---
 embassy-nrf/src/time_driver.rs | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/embassy-nrf/src/time_driver.rs b/embassy-nrf/src/time_driver.rs
index 0f31c5c9c..b41169c01 100644
--- a/embassy-nrf/src/time_driver.rs
+++ b/embassy-nrf/src/time_driver.rs
@@ -1,11 +1,11 @@
 use core::cell::Cell;
 use core::{mem, ptr};
 
+use core::sync::atomic::{compiler_fence, AtomicU32, AtomicU8, Ordering};
 use critical_section::CriticalSection;
 use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
 use embassy_sync::blocking_mutex::CriticalSectionMutex as Mutex;
 use embassy_time_driver::{AlarmHandle, Driver};
-use portable_atomic::{compiler_fence, AtomicU32, AtomicU8, Ordering};
 
 use crate::interrupt::InterruptExt;
 use crate::{interrupt, pac};
@@ -171,7 +171,8 @@ impl RtcDriver {
     fn next_period(&self) {
         critical_section::with(|cs| {
             let r = rtc();
-            let period = self.period.fetch_add(1, Ordering::Relaxed) + 1;
+            let period = self.period.load(Ordering::Relaxed) + 1;
+            self.period.store(period, Ordering::Relaxed);
             let t = (period as u64) << 23;
 
             for n in 0..ALARM_COUNT {
@@ -219,18 +220,15 @@ impl Driver for RtcDriver {
     }
 
     unsafe fn allocate_alarm(&self) -> Option<AlarmHandle> {
-        let id = self.alarm_count.fetch_update(Ordering::AcqRel, Ordering::Acquire, |x| {
-            if x < ALARM_COUNT as u8 {
-                Some(x + 1)
+        critical_section::with(|_| {
+            let id = self.alarm_count.load(Ordering::Relaxed);
+            if id < ALARM_COUNT as u8 {
+                self.alarm_count.store(id + 1, Ordering::Relaxed);
+                Some(AlarmHandle::new(id))
             } else {
                 None
             }
-        });
-
-        match id {
-            Ok(id) => Some(AlarmHandle::new(id)),
-            Err(_) => None,
-        }
+        })
     }
 
     fn set_alarm_callback(&self, alarm: AlarmHandle, callback: fn(*mut ()), ctx: *mut ()) {

From 3ac52b2c4857048d56d943ed24c6d72847e60f0a Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Wed, 24 Jan 2024 19:28:05 +0100
Subject: [PATCH 07/27] remove portable-atomic dependency

---
 embassy-nrf/Cargo.toml | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/embassy-nrf/Cargo.toml b/embassy-nrf/Cargo.toml
index 529a56c46..a682e1227 100644
--- a/embassy-nrf/Cargo.toml
+++ b/embassy-nrf/Cargo.toml
@@ -74,7 +74,7 @@ qspi-multiwrite-flash = []
 
 #! ### Chip selection features
 ## nRF51
-nrf51 = ["nrf51-pac", "_nrf51", "portable-atomic/unsafe-assume-single-core"]
+nrf51 = ["nrf51-pac", "_nrf51"]
 ## nRF52805
 nrf52805 = ["nrf52805-pac", "_nrf52"]
 ## nRF52810
@@ -137,8 +137,6 @@ embedded-hal-async = { version = "1.0" }
 embedded-io = { version = "0.6.0" }
 embedded-io-async = { version = "0.6.1" }
 
-portable-atomic = { version = "1", default-features = false, features = ["require-cas"] }
-
 defmt = { version = "0.3", optional = true }
 log = { version = "0.4.14", optional = true }
 cortex-m-rt = ">=0.6.15,<0.8"

From 7d961a7f447a56a458a556b747710ec3375950d7 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Wed, 24 Jan 2024 19:28:28 +0100
Subject: [PATCH 08/27] cargo fmt

---
 embassy-nrf/src/rng.rs | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/embassy-nrf/src/rng.rs b/embassy-nrf/src/rng.rs
index 6145dd14f..a65ad5518 100644
--- a/embassy-nrf/src/rng.rs
+++ b/embassy-nrf/src/rng.rs
@@ -44,7 +44,6 @@ impl<T: Instance> interrupt::typelevel::Handler<T::Interrupt> for InterruptHandl
                 if state.ptr == state.end {
                     state.waker.wake();
                 }
-
             }
         });
     }
@@ -113,7 +112,6 @@ impl<'d, T: Instance> Rng<'d, T> {
             return; // Nothing to fill
         }
 
-
         let range = dest.as_mut_ptr_range();
         // Even if we've preempted the interrupt, it can't preempt us again,
         // so we don't need to worry about the order we write these in.
@@ -208,10 +206,10 @@ impl<'d, T: Instance> rand_core::RngCore for Rng<'d, T> {
 impl<'d, T: Instance> rand_core::CryptoRng for Rng<'d, T> {}
 
 pub(crate) mod sealed {
-    use core::cell::{Ref, RefMut, RefCell};
+    use core::cell::{Ref, RefCell, RefMut};
 
-    use critical_section::Mutex;
     use critical_section::CriticalSection;
+    use critical_section::Mutex;
     use embassy_sync::waitqueue::WakerRegistration;
 
     use super::*;

From 85d7779668ce14abbde4cd8fb1ea9395df529206 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Wed, 24 Jan 2024 19:30:46 +0100
Subject: [PATCH 09/27] rename nrf52 HIL test

---
 ci.sh                                                     | 2 +-
 tests/{nrf => nrf52840}/.cargo/config.toml                | 0
 tests/{nrf => nrf52840}/Cargo.toml                        | 0
 tests/{nrf => nrf52840}/build.rs                          | 0
 tests/{nrf => nrf52840}/memory.x                          | 0
 tests/{nrf => nrf52840}/src/bin/buffered_uart.rs          | 0
 tests/{nrf => nrf52840}/src/bin/buffered_uart_full.rs     | 0
 tests/{nrf => nrf52840}/src/bin/buffered_uart_spam.rs     | 0
 tests/{nrf => nrf52840}/src/bin/ethernet_enc28j60_perf.rs | 0
 tests/{nrf => nrf52840}/src/bin/timer.rs                  | 0
 tests/{nrf => nrf52840}/src/bin/wifi_esp_hosted_perf.rs   | 0
 11 files changed, 1 insertion(+), 1 deletion(-)
 rename tests/{nrf => nrf52840}/.cargo/config.toml (100%)
 rename tests/{nrf => nrf52840}/Cargo.toml (100%)
 rename tests/{nrf => nrf52840}/build.rs (100%)
 rename tests/{nrf => nrf52840}/memory.x (100%)
 rename tests/{nrf => nrf52840}/src/bin/buffered_uart.rs (100%)
 rename tests/{nrf => nrf52840}/src/bin/buffered_uart_full.rs (100%)
 rename tests/{nrf => nrf52840}/src/bin/buffered_uart_spam.rs (100%)
 rename tests/{nrf => nrf52840}/src/bin/ethernet_enc28j60_perf.rs (100%)
 rename tests/{nrf => nrf52840}/src/bin/timer.rs (100%)
 rename tests/{nrf => nrf52840}/src/bin/wifi_esp_hosted_perf.rs (100%)

diff --git a/ci.sh b/ci.sh
index 3322c60d1..cf12f95fd 100755
--- a/ci.sh
+++ b/ci.sh
@@ -211,7 +211,7 @@ cargo batch  \
     --- build --release --manifest-path tests/stm32/Cargo.toml --target thumbv7em-none-eabi --features stm32l496zg --out-dir out/tests/stm32l496zg \
     --- build --release --manifest-path tests/stm32/Cargo.toml --target thumbv7em-none-eabi --features stm32wl55jc --out-dir out/tests/stm32wl55jc \
     --- build --release --manifest-path tests/rp/Cargo.toml --target thumbv6m-none-eabi --out-dir out/tests/rpi-pico \
-    --- build --release --manifest-path tests/nrf/Cargo.toml --target thumbv7em-none-eabi --out-dir out/tests/nrf52840-dk \
+    --- build --release --manifest-path tests/nrf52840/Cargo.toml --target thumbv7em-none-eabi --out-dir out/tests/nrf52840-dk \
     --- build --release --manifest-path tests/riscv32/Cargo.toml --target riscv32imac-unknown-none-elf \
     $BUILD_EXTRA
 
diff --git a/tests/nrf/.cargo/config.toml b/tests/nrf52840/.cargo/config.toml
similarity index 100%
rename from tests/nrf/.cargo/config.toml
rename to tests/nrf52840/.cargo/config.toml
diff --git a/tests/nrf/Cargo.toml b/tests/nrf52840/Cargo.toml
similarity index 100%
rename from tests/nrf/Cargo.toml
rename to tests/nrf52840/Cargo.toml
diff --git a/tests/nrf/build.rs b/tests/nrf52840/build.rs
similarity index 100%
rename from tests/nrf/build.rs
rename to tests/nrf52840/build.rs
diff --git a/tests/nrf/memory.x b/tests/nrf52840/memory.x
similarity index 100%
rename from tests/nrf/memory.x
rename to tests/nrf52840/memory.x
diff --git a/tests/nrf/src/bin/buffered_uart.rs b/tests/nrf52840/src/bin/buffered_uart.rs
similarity index 100%
rename from tests/nrf/src/bin/buffered_uart.rs
rename to tests/nrf52840/src/bin/buffered_uart.rs
diff --git a/tests/nrf/src/bin/buffered_uart_full.rs b/tests/nrf52840/src/bin/buffered_uart_full.rs
similarity index 100%
rename from tests/nrf/src/bin/buffered_uart_full.rs
rename to tests/nrf52840/src/bin/buffered_uart_full.rs
diff --git a/tests/nrf/src/bin/buffered_uart_spam.rs b/tests/nrf52840/src/bin/buffered_uart_spam.rs
similarity index 100%
rename from tests/nrf/src/bin/buffered_uart_spam.rs
rename to tests/nrf52840/src/bin/buffered_uart_spam.rs
diff --git a/tests/nrf/src/bin/ethernet_enc28j60_perf.rs b/tests/nrf52840/src/bin/ethernet_enc28j60_perf.rs
similarity index 100%
rename from tests/nrf/src/bin/ethernet_enc28j60_perf.rs
rename to tests/nrf52840/src/bin/ethernet_enc28j60_perf.rs
diff --git a/tests/nrf/src/bin/timer.rs b/tests/nrf52840/src/bin/timer.rs
similarity index 100%
rename from tests/nrf/src/bin/timer.rs
rename to tests/nrf52840/src/bin/timer.rs
diff --git a/tests/nrf/src/bin/wifi_esp_hosted_perf.rs b/tests/nrf52840/src/bin/wifi_esp_hosted_perf.rs
similarity index 100%
rename from tests/nrf/src/bin/wifi_esp_hosted_perf.rs
rename to tests/nrf52840/src/bin/wifi_esp_hosted_perf.rs

From db0f4a0b91cc89aef58a6345743fb51ffe1be3a4 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Wed, 24 Jan 2024 20:19:34 +0100
Subject: [PATCH 10/27] cleanup

---
 embassy-nrf/src/chips/nrf51.rs | 8 +++++---
 embassy-nrf/src/ppi/mod.rs     | 1 +
 embassy-nrf/src/ppi/ppi.rs     | 4 ++--
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/embassy-nrf/src/chips/nrf51.rs b/embassy-nrf/src/chips/nrf51.rs
index f5db4b847..e7147ac93 100644
--- a/embassy-nrf/src/chips/nrf51.rs
+++ b/embassy-nrf/src/chips/nrf51.rs
@@ -102,9 +102,11 @@ embassy_hal_internal::peripherals! {
     TEMP,
 }
 
-// impl_timer!(TIMER0, TIMER0, TIMER0);
-// impl_timer!(TIMER1, TIMER1, TIMER1);
-// impl_timer!(TIMER2, TIMER2, TIMER2);
+impl_timer!(TIMER0, TIMER0, TIMER0);
+impl_timer!(TIMER1, TIMER1, TIMER1);
+impl_timer!(TIMER2, TIMER2, TIMER2);
+
+impl_rng!(RNG, RNG, RNG);
 
 impl_pin!(P0_00, 0, 0);
 impl_pin!(P0_01, 0, 1);
diff --git a/embassy-nrf/src/ppi/mod.rs b/embassy-nrf/src/ppi/mod.rs
index 5b4a64388..f5764b8b7 100644
--- a/embassy-nrf/src/ppi/mod.rs
+++ b/embassy-nrf/src/ppi/mod.rs
@@ -284,6 +284,7 @@ impl ConfigurableChannel for AnyConfigurableChannel {
     }
 }
 
+#[cfg(not(feature = "nrf51"))]
 macro_rules! impl_ppi_channel {
     ($type:ident, $number:expr) => {
         impl crate::ppi::sealed::Channel for peripherals::$type {}
diff --git a/embassy-nrf/src/ppi/ppi.rs b/embassy-nrf/src/ppi/ppi.rs
index 4a12764ad..8ff52ece3 100644
--- a/embassy-nrf/src/ppi/ppi.rs
+++ b/embassy-nrf/src/ppi/ppi.rs
@@ -1,6 +1,6 @@
 use embassy_hal_internal::into_ref;
 
-use super::{Channel, ConfigurableChannel, Event, Ppi, StaticChannel, Task};
+use super::{Channel, ConfigurableChannel, Event, Ppi, Task};
 use crate::{pac, Peripheral};
 
 impl<'d> Task<'d> {
@@ -19,7 +19,7 @@ pub(crate) fn regs() -> &'static pac::ppi::RegisterBlock {
 }
 
 #[cfg(not(feature = "nrf51"))] // Not for nrf51 because of the fork task
-impl<'d, C: StaticChannel> Ppi<'d, C, 0, 1> {
+impl<'d, C: super::StaticChannel> Ppi<'d, C, 0, 1> {
     /// Configure PPI channel to trigger `task`.
     pub fn new_zero_to_one(ch: impl Peripheral<P = C> + 'd, task: Task) -> Self {
         into_ref!(ch);

From 1989c229f99b1177133af51d514ba44a5b02fe6f Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 08:38:01 +0100
Subject: [PATCH 11/27] fix: make inner state send as it's protected critical
 section

---
 embassy-nrf/src/rng.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/embassy-nrf/src/rng.rs b/embassy-nrf/src/rng.rs
index a65ad5518..667637bfa 100644
--- a/embassy-nrf/src/rng.rs
+++ b/embassy-nrf/src/rng.rs
@@ -225,6 +225,8 @@ pub(crate) mod sealed {
         pub waker: WakerRegistration,
     }
 
+    unsafe impl Send for InnerState {}
+
     impl State {
         pub const fn new() -> Self {
             Self {

From 3739cc069914861d891a21734b3da9418bd01e9f Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 08:38:28 +0100
Subject: [PATCH 12/27] fix warnings

---
 embassy-nrf/src/chips/nrf51.rs | 1 -
 embassy-nrf/src/gpio.rs        | 1 +
 embassy-nrf/src/lib.rs         | 4 ++++
 embassy-nrf/src/timer.rs       | 4 ++--
 embassy-nrf/src/util.rs        | 1 +
 5 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/embassy-nrf/src/chips/nrf51.rs b/embassy-nrf/src/chips/nrf51.rs
index e7147ac93..016352fb8 100644
--- a/embassy-nrf/src/chips/nrf51.rs
+++ b/embassy-nrf/src/chips/nrf51.rs
@@ -2,7 +2,6 @@ pub use nrf51_pac as pac;
 
 /// The maximum buffer size that the EasyDMA can send/recv in one operation.
 pub const EASY_DMA_SIZE: usize = (1 << 14) - 1;
-pub const FORCE_COPY_BUFFER_SIZE: usize = 256;
 
 pub const FLASH_SIZE: usize = 128 * 1024;
 
diff --git a/embassy-nrf/src/gpio.rs b/embassy-nrf/src/gpio.rs
index b1eb8ae87..b2f987109 100644
--- a/embassy-nrf/src/gpio.rs
+++ b/embassy-nrf/src/gpio.rs
@@ -487,6 +487,7 @@ impl<'a, P: Pin> PselBits for Option<PeripheralRef<'a, P>> {
     }
 }
 
+#[allow(dead_code)]
 pub(crate) fn deconfigure_pin(psel_bits: u32) {
     if psel_bits & 0x8000_0000 != 0 {
         return;
diff --git a/embassy-nrf/src/lib.rs b/embassy-nrf/src/lib.rs
index 923e48ec2..358a7cc27 100644
--- a/embassy-nrf/src/lib.rs
+++ b/embassy-nrf/src/lib.rs
@@ -336,6 +336,7 @@ mod consts {
     pub const APPROTECT_DISABLED: u32 = 0x0000_005a;
 }
 
+#[cfg(not(feature = "nrf51"))]
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 enum WriteResult {
@@ -347,10 +348,12 @@ enum WriteResult {
     Failed,
 }
 
+#[cfg(not(feature = "nrf51"))]
 unsafe fn uicr_write(address: *mut u32, value: u32) -> WriteResult {
     uicr_write_masked(address, value, 0xFFFF_FFFF)
 }
 
+#[cfg(not(feature = "nrf51"))]
 unsafe fn uicr_write_masked(address: *mut u32, value: u32, mask: u32) -> WriteResult {
     let curr_val = address.read_volatile();
     if curr_val & mask == value & mask {
@@ -383,6 +386,7 @@ pub fn init(config: config::Config) -> Peripherals {
     // before doing anything important.
     let peripherals = Peripherals::take();
 
+    #[allow(unused_mut)]
     let mut needs_reset = false;
 
     // Setup debug protection.
diff --git a/embassy-nrf/src/timer.rs b/embassy-nrf/src/timer.rs
index 272fffc0a..3c35baee5 100644
--- a/embassy-nrf/src/timer.rs
+++ b/embassy-nrf/src/timer.rs
@@ -111,7 +111,7 @@ impl<'d, T: Instance> Timer<'d, T> {
         Self::new_inner(timer, true)
     }
 
-    fn new_inner(timer: impl Peripheral<P = T> + 'd, is_counter: bool) -> Self {
+    fn new_inner(timer: impl Peripheral<P = T> + 'd, _is_counter: bool) -> Self {
         into_ref!(timer);
 
         let regs = T::regs();
@@ -123,7 +123,7 @@ impl<'d, T: Instance> Timer<'d, T> {
         this.stop();
 
         #[cfg(not(feature = "nrf51"))]
-        if is_counter {
+        if _is_counter {
             regs.mode.write(|w| w.mode().low_power_counter());
         } else {
             regs.mode.write(|w| w.mode().timer());
diff --git a/embassy-nrf/src/util.rs b/embassy-nrf/src/util.rs
index cd0f59490..b408c517b 100644
--- a/embassy-nrf/src/util.rs
+++ b/embassy-nrf/src/util.rs
@@ -1,3 +1,4 @@
+#![allow(dead_code)]
 use core::mem;
 
 const SRAM_LOWER: usize = 0x2000_0000;

From 1263d28595d7f92e348c866764e6e6275b08967f Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 08:39:25 +0100
Subject: [PATCH 13/27] nightly fmt

---
 embassy-nrf/src/rng.rs         | 3 +--
 embassy-nrf/src/time_driver.rs | 2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/embassy-nrf/src/rng.rs b/embassy-nrf/src/rng.rs
index 667637bfa..40b73231b 100644
--- a/embassy-nrf/src/rng.rs
+++ b/embassy-nrf/src/rng.rs
@@ -208,8 +208,7 @@ impl<'d, T: Instance> rand_core::CryptoRng for Rng<'d, T> {}
 pub(crate) mod sealed {
     use core::cell::{Ref, RefCell, RefMut};
 
-    use critical_section::CriticalSection;
-    use critical_section::Mutex;
+    use critical_section::{CriticalSection, Mutex};
     use embassy_sync::waitqueue::WakerRegistration;
 
     use super::*;
diff --git a/embassy-nrf/src/time_driver.rs b/embassy-nrf/src/time_driver.rs
index b41169c01..3407c9504 100644
--- a/embassy-nrf/src/time_driver.rs
+++ b/embassy-nrf/src/time_driver.rs
@@ -1,7 +1,7 @@
 use core::cell::Cell;
+use core::sync::atomic::{compiler_fence, AtomicU32, AtomicU8, Ordering};
 use core::{mem, ptr};
 
-use core::sync::atomic::{compiler_fence, AtomicU32, AtomicU8, Ordering};
 use critical_section::CriticalSection;
 use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
 use embassy_sync::blocking_mutex::CriticalSectionMutex as Mutex;

From 9418f0f9e53ceddfcaefe90a7fd3ad308f440758 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 14:05:45 +0100
Subject: [PATCH 14/27] add HIL test to CI

---
 ci.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ci.sh b/ci.sh
index cf12f95fd..1299dc2c9 100755
--- a/ci.sh
+++ b/ci.sh
@@ -212,6 +212,7 @@ cargo batch  \
     --- build --release --manifest-path tests/stm32/Cargo.toml --target thumbv7em-none-eabi --features stm32wl55jc --out-dir out/tests/stm32wl55jc \
     --- build --release --manifest-path tests/rp/Cargo.toml --target thumbv6m-none-eabi --out-dir out/tests/rpi-pico \
     --- build --release --manifest-path tests/nrf52840/Cargo.toml --target thumbv7em-none-eabi --out-dir out/tests/nrf52840-dk \
+    --- build --release --manifest-path tests/nrf51822/Cargo.toml --target thumbv6m-none-eabi --out-dir out/tests/nrf51-dk \
     --- build --release --manifest-path tests/riscv32/Cargo.toml --target riscv32imac-unknown-none-elf \
     $BUILD_EXTRA
 

From 7e6bc64331ad2fad71791ac4e0eb76667212f475 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 14:23:57 +0100
Subject: [PATCH 15/27] fix: add missing hil test project

---
 tests/nrf51822/.cargo/config.toml |  9 +++++++++
 tests/nrf51822/Cargo.toml         | 22 ++++++++++++++++++++++
 tests/nrf51822/build.rs           | 17 +++++++++++++++++
 tests/nrf51822/memory.x           |  5 +++++
 tests/nrf51822/src/bin/gpio.rs    | 28 ++++++++++++++++++++++++++++
 tests/nrf51822/src/bin/timer.rs   | 25 +++++++++++++++++++++++++
 6 files changed, 106 insertions(+)
 create mode 100644 tests/nrf51822/.cargo/config.toml
 create mode 100644 tests/nrf51822/Cargo.toml
 create mode 100644 tests/nrf51822/build.rs
 create mode 100644 tests/nrf51822/memory.x
 create mode 100644 tests/nrf51822/src/bin/gpio.rs
 create mode 100644 tests/nrf51822/src/bin/timer.rs

diff --git a/tests/nrf51822/.cargo/config.toml b/tests/nrf51822/.cargo/config.toml
new file mode 100644
index 000000000..3d0c71092
--- /dev/null
+++ b/tests/nrf51822/.cargo/config.toml
@@ -0,0 +1,9 @@
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+#runner = "teleprobe local run --chip nRF51822_xxAA --elf"
+runner = "teleprobe client run"
+
+[build]
+target = "thumbv6m-none-eabi"
+
+[env]
+DEFMT_LOG = "trace,embassy_hal_internal=debug"
diff --git a/tests/nrf51822/Cargo.toml b/tests/nrf51822/Cargo.toml
new file mode 100644
index 000000000..468fa03fa
--- /dev/null
+++ b/tests/nrf51822/Cargo.toml
@@ -0,0 +1,22 @@
+[package]
+edition = "2021"
+name = "embassy-nrf51822-tests"
+version = "0.1.0"
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+teleprobe-meta = "1"
+
+embassy-sync = { version = "0.5.0", path = "../../embassy-sync", features = ["defmt", ] }
+embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["arch-cortex-m", "executor-thread", "defmt", "task-arena-size-8192", "integrated-timers"] }
+embassy-time = { version = "0.3.0", path = "../../embassy-time", features = ["defmt",  "defmt-timestamp-uptime"] }
+embassy-nrf = { version = "0.1.0", path = "../../embassy-nrf", features = ["defmt",  "nrf51", "time-driver-rtc1", "unstable-pac"] }
+embedded-io-async = { version = "0.6.1", features = ["defmt-03"] }
+embedded-hal-async = { version = "1.0" }
+
+defmt = "0.3"
+defmt-rtt = "0.4"
+
+cortex-m = { version = "0.7.6", features = ["critical-section-single-core"] }
+cortex-m-rt = "0.7.0"
+panic-probe = { version = "0.3", features = ["print-defmt"] }
diff --git a/tests/nrf51822/build.rs b/tests/nrf51822/build.rs
new file mode 100644
index 000000000..71c82a70f
--- /dev/null
+++ b/tests/nrf51822/build.rs
@@ -0,0 +1,17 @@
+use std::error::Error;
+use std::path::PathBuf;
+use std::{env, fs};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let out = PathBuf::from(env::var("OUT_DIR").unwrap());
+    fs::write(out.join("link_ram.x"), include_bytes!("../link_ram_cortex_m.x")).unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+    println!("cargo:rerun-if-changed=link_ram.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink_ram.x");
+    println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+    println!("cargo:rustc-link-arg-bins=-Tteleprobe.x");
+
+    Ok(())
+}
diff --git a/tests/nrf51822/memory.x b/tests/nrf51822/memory.x
new file mode 100644
index 000000000..c140005ce
--- /dev/null
+++ b/tests/nrf51822/memory.x
@@ -0,0 +1,5 @@
+MEMORY
+{
+  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
+  RAM : ORIGIN = 0x20000000, LENGTH = 32K
+}
diff --git a/tests/nrf51822/src/bin/gpio.rs b/tests/nrf51822/src/bin/gpio.rs
new file mode 100644
index 000000000..6c6bc0839
--- /dev/null
+++ b/tests/nrf51822/src/bin/gpio.rs
@@ -0,0 +1,28 @@
+#![no_std]
+#![no_main]
+teleprobe_meta::target!(b"nrf51-dk");
+
+use defmt::{assert, info};
+use embassy_executor::Spawner;
+use embassy_nrf::gpio::{Input, Level, Output, OutputDrive, Pull};
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_nrf::init(Default::default());
+
+    let input = Input::new(p.P0_13, Pull::None);
+    let mut output = Output::new(p.P0_14, Level::Low, OutputDrive::Standard);
+
+    output.set_low();
+    Timer::after_millis(1).await;
+    assert!(input.is_low());
+
+    output.set_high();
+    Timer::after_millis(1).await;
+    assert!(input.is_high());
+
+    info!("Test OK");
+    cortex_m::asm::bkpt();
+}
diff --git a/tests/nrf51822/src/bin/timer.rs b/tests/nrf51822/src/bin/timer.rs
new file mode 100644
index 000000000..2a147e7ba
--- /dev/null
+++ b/tests/nrf51822/src/bin/timer.rs
@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+teleprobe_meta::target!(b"nrf52840-dk");
+
+use defmt::{assert, info};
+use embassy_executor::Spawner;
+use embassy_time::{Instant, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let _p = embassy_nrf::init(Default::default());
+    info!("Hello World!");
+
+    let start = Instant::now();
+    Timer::after_millis(100).await;
+    let end = Instant::now();
+    let ms = (end - start).as_millis();
+    info!("slept for {} ms", ms);
+    assert!(ms >= 99);
+    assert!(ms < 110);
+
+    info!("Test OK");
+    cortex_m::asm::bkpt();
+}

From d19c67023d45ac7482bc05f1cea994abd97d0a2d Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 14:36:51 +0100
Subject: [PATCH 16/27] fix: teleprobe target

---
 tests/nrf51822/src/bin/timer.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/nrf51822/src/bin/timer.rs b/tests/nrf51822/src/bin/timer.rs
index 2a147e7ba..93f4c2b1c 100644
--- a/tests/nrf51822/src/bin/timer.rs
+++ b/tests/nrf51822/src/bin/timer.rs
@@ -1,6 +1,6 @@
 #![no_std]
 #![no_main]
-teleprobe_meta::target!(b"nrf52840-dk");
+teleprobe_meta::target!(b"nrf51-dk");
 
 use defmt::{assert, info};
 use embassy_executor::Spawner;

From 309dda057d05cd0c197ffe2befa271e9cad314b7 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 14:39:09 +0100
Subject: [PATCH 17/27] add nrf51 builds to ci

---
 ci.sh | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/ci.sh b/ci.sh
index 1299dc2c9..d29a686af 100755
--- a/ci.sh
+++ b/ci.sh
@@ -67,6 +67,9 @@ cargo batch  \
     --- build --release --manifest-path embassy-nrf/Cargo.toml --target thumbv7em-none-eabi --features nrf52840,gpiote,defmt,time \
     --- build --release --manifest-path embassy-nrf/Cargo.toml --target thumbv7em-none-eabi --features nrf52840,gpiote,defmt,time-driver-rtc1 \
     --- build --release --manifest-path embassy-nrf/Cargo.toml --target thumbv7em-none-eabi --features nrf52840,gpiote,defmt,time,time-driver-rtc1 \
+    --- build --release --manifest-path embassy-nrf/Cargo.toml --target thumbv6m-none-eabi --features nrf51,defmt,time,time-driver-rtc1 \
+    --- build --release --manifest-path embassy-nrf/Cargo.toml --target thumbv6m-none-eabi --features nrf51,defmt,time \
+    --- build --release --manifest-path embassy-nrf/Cargo.toml --target thumbv6m-none-eabi --features nrf51,time \
     --- build --release --manifest-path embassy-rp/Cargo.toml --target thumbv6m-none-eabi --features time-driver,defmt \
     --- build --release --manifest-path embassy-rp/Cargo.toml --target thumbv6m-none-eabi --features time-driver,log \
     --- build --release --manifest-path embassy-rp/Cargo.toml --target thumbv6m-none-eabi --features time-driver,intrinsics \
@@ -148,6 +151,7 @@ cargo batch  \
     --- build --release --manifest-path examples/nrf52840/Cargo.toml --target thumbv7em-none-eabi --out-dir out/examples/nrf52840 \
     --- build --release --manifest-path examples/nrf5340/Cargo.toml --target thumbv8m.main-none-eabihf --out-dir out/examples/nrf5340 \
     --- build --release --manifest-path examples/nrf9160/Cargo.toml --target thumbv8m.main-none-eabihf --out-dir out/examples/nrf9160 \
+    --- build --release --manifest-path examples/nrf51/Cargo.toml --target thumbv6m-none-eabi --out-dir out/examples/nrf51 \
     --- build --release --manifest-path examples/rp/Cargo.toml --target thumbv6m-none-eabi --out-dir out/examples/rp \
     --- build --release --manifest-path examples/stm32f0/Cargo.toml --target thumbv6m-none-eabi --out-dir out/examples/stm32f0 \
     --- build --release --manifest-path examples/stm32f1/Cargo.toml --target thumbv7m-none-eabi --out-dir out/examples/stm32f1 \

From f117213b6ee80c224e781d7bf4e750df49c345a6 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 21:47:49 +0100
Subject: [PATCH 18/27] fix: use nrf51-dk chip variant

---
 ci.sh                                           | 2 +-
 examples/nrf51/.cargo/config.toml               | 4 ++--
 tests/{nrf51822 => nrf51422}/.cargo/config.toml | 2 +-
 tests/{nrf51822 => nrf51422}/Cargo.toml         | 2 +-
 tests/{nrf51822 => nrf51422}/build.rs           | 0
 tests/{nrf51822 => nrf51422}/memory.x           | 0
 tests/{nrf51822 => nrf51422}/src/bin/gpio.rs    | 0
 tests/{nrf51822 => nrf51422}/src/bin/timer.rs   | 0
 8 files changed, 5 insertions(+), 5 deletions(-)
 rename tests/{nrf51822 => nrf51422}/.cargo/config.toml (75%)
 rename tests/{nrf51822 => nrf51422}/Cargo.toml (96%)
 rename tests/{nrf51822 => nrf51422}/build.rs (100%)
 rename tests/{nrf51822 => nrf51422}/memory.x (100%)
 rename tests/{nrf51822 => nrf51422}/src/bin/gpio.rs (100%)
 rename tests/{nrf51822 => nrf51422}/src/bin/timer.rs (100%)

diff --git a/ci.sh b/ci.sh
index d29a686af..6a5e6e3f5 100755
--- a/ci.sh
+++ b/ci.sh
@@ -216,7 +216,7 @@ cargo batch  \
     --- build --release --manifest-path tests/stm32/Cargo.toml --target thumbv7em-none-eabi --features stm32wl55jc --out-dir out/tests/stm32wl55jc \
     --- build --release --manifest-path tests/rp/Cargo.toml --target thumbv6m-none-eabi --out-dir out/tests/rpi-pico \
     --- build --release --manifest-path tests/nrf52840/Cargo.toml --target thumbv7em-none-eabi --out-dir out/tests/nrf52840-dk \
-    --- build --release --manifest-path tests/nrf51822/Cargo.toml --target thumbv6m-none-eabi --out-dir out/tests/nrf51-dk \
+    --- build --release --manifest-path tests/nrf51422/Cargo.toml --target thumbv6m-none-eabi --out-dir out/tests/nrf51-dk \
     --- build --release --manifest-path tests/riscv32/Cargo.toml --target riscv32imac-unknown-none-elf \
     $BUILD_EXTRA
 
diff --git a/examples/nrf51/.cargo/config.toml b/examples/nrf51/.cargo/config.toml
index 29d35a9b4..1671f5db1 100644
--- a/examples/nrf51/.cargo/config.toml
+++ b/examples/nrf51/.cargo/config.toml
@@ -1,6 +1,6 @@
 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
-# replace nRF51822_xxAA with your chip as listed in `probe-rs chip list`
-runner = "probe-rs run --chip nRF51822_xxAA"
+# replace nRF51422_xxAA with your chip as listed in `probe-rs chip list`
+runner = "probe-rs run --chip nRF51422_xxAA"
 
 [build]
 target = "thumbv6m-none-eabi"
diff --git a/tests/nrf51822/.cargo/config.toml b/tests/nrf51422/.cargo/config.toml
similarity index 75%
rename from tests/nrf51822/.cargo/config.toml
rename to tests/nrf51422/.cargo/config.toml
index 3d0c71092..634805633 100644
--- a/tests/nrf51822/.cargo/config.toml
+++ b/tests/nrf51422/.cargo/config.toml
@@ -1,5 +1,5 @@
 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
-#runner = "teleprobe local run --chip nRF51822_xxAA --elf"
+#runner = "teleprobe local run --chip nRF51422_xxAA --elf"
 runner = "teleprobe client run"
 
 [build]
diff --git a/tests/nrf51822/Cargo.toml b/tests/nrf51422/Cargo.toml
similarity index 96%
rename from tests/nrf51822/Cargo.toml
rename to tests/nrf51422/Cargo.toml
index 468fa03fa..d95f122b0 100644
--- a/tests/nrf51822/Cargo.toml
+++ b/tests/nrf51422/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 edition = "2021"
-name = "embassy-nrf51822-tests"
+name = "embassy-nrf51-tests"
 version = "0.1.0"
 license = "MIT OR Apache-2.0"
 
diff --git a/tests/nrf51822/build.rs b/tests/nrf51422/build.rs
similarity index 100%
rename from tests/nrf51822/build.rs
rename to tests/nrf51422/build.rs
diff --git a/tests/nrf51822/memory.x b/tests/nrf51422/memory.x
similarity index 100%
rename from tests/nrf51822/memory.x
rename to tests/nrf51422/memory.x
diff --git a/tests/nrf51822/src/bin/gpio.rs b/tests/nrf51422/src/bin/gpio.rs
similarity index 100%
rename from tests/nrf51822/src/bin/gpio.rs
rename to tests/nrf51422/src/bin/gpio.rs
diff --git a/tests/nrf51822/src/bin/timer.rs b/tests/nrf51422/src/bin/timer.rs
similarity index 100%
rename from tests/nrf51822/src/bin/timer.rs
rename to tests/nrf51422/src/bin/timer.rs

From b16eca3f21f947dcd4b3fe279bd4f577679428bc Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 21:50:03 +0100
Subject: [PATCH 19/27] adjust memory settings for lower end variant

---
 examples/nrf51/memory.x | 4 ++--
 tests/nrf51422/memory.x | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/examples/nrf51/memory.x b/examples/nrf51/memory.x
index ad5f80292..98b3c792f 100644
--- a/examples/nrf51/memory.x
+++ b/examples/nrf51/memory.x
@@ -1,5 +1,5 @@
 MEMORY
 {
-  FLASH                    : ORIGIN = 0x00000000, LENGTH = 256K
-  RAM                      : ORIGIN = 0x20000000, LENGTH = 32K
+  FLASH                    : ORIGIN = 0x00000000, LENGTH = 128K
+  RAM                      : ORIGIN = 0x20000000, LENGTH = 16K
 }
diff --git a/tests/nrf51422/memory.x b/tests/nrf51422/memory.x
index c140005ce..a5881e66f 100644
--- a/tests/nrf51422/memory.x
+++ b/tests/nrf51422/memory.x
@@ -1,5 +1,5 @@
 MEMORY
 {
-  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
-  RAM : ORIGIN = 0x20000000, LENGTH = 32K
+  FLASH : ORIGIN = 0x00000000, LENGTH = 128K
+  RAM : ORIGIN = 0x20000000, LENGTH = 16K
 }

From 43553381cda95b75d9de1460d5ea6add6e739134 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Thu, 25 Jan 2024 21:51:23 +0100
Subject: [PATCH 20/27] lower arena for nrf51

---
 examples/nrf51/Cargo.toml | 2 +-
 tests/nrf51422/Cargo.toml | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/examples/nrf51/Cargo.toml b/examples/nrf51/Cargo.toml
index 8507c415c..d1e919a33 100644
--- a/examples/nrf51/Cargo.toml
+++ b/examples/nrf51/Cargo.toml
@@ -5,7 +5,7 @@ version = "0.1.0"
 license = "MIT OR Apache-2.0"
 
 [dependencies]
-embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["task-arena-size-8192", "arch-cortex-m", "executor-thread", "executor-interrupt", "defmt", "integrated-timers"] }
+embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["task-arena-size-4096", "arch-cortex-m", "executor-thread", "executor-interrupt", "defmt", "integrated-timers"] }
 embassy-time = { version = "0.3.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime"] }
 embassy-nrf = { version = "0.1.0", path = "../../embassy-nrf", features = ["defmt", "nrf51", "time-driver-rtc1", "unstable-pac", "time", "rt"] }
 
diff --git a/tests/nrf51422/Cargo.toml b/tests/nrf51422/Cargo.toml
index d95f122b0..246b71117 100644
--- a/tests/nrf51422/Cargo.toml
+++ b/tests/nrf51422/Cargo.toml
@@ -8,7 +8,7 @@ license = "MIT OR Apache-2.0"
 teleprobe-meta = "1"
 
 embassy-sync = { version = "0.5.0", path = "../../embassy-sync", features = ["defmt", ] }
-embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["arch-cortex-m", "executor-thread", "defmt", "task-arena-size-8192", "integrated-timers"] }
+embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["arch-cortex-m", "executor-thread", "defmt", "task-arena-size-4096", "integrated-timers"] }
 embassy-time = { version = "0.3.0", path = "../../embassy-time", features = ["defmt",  "defmt-timestamp-uptime"] }
 embassy-nrf = { version = "0.1.0", path = "../../embassy-nrf", features = ["defmt",  "nrf51", "time-driver-rtc1", "unstable-pac"] }
 embedded-io-async = { version = "0.6.1", features = ["defmt-03"] }

From 2f347ece9149551bd9db1068179f74500641a33e Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Fri, 26 Jan 2024 08:00:50 +0100
Subject: [PATCH 21/27] add simplest test

---
 tests/nrf51422/src/bin/test.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 tests/nrf51422/src/bin/test.rs

diff --git a/tests/nrf51422/src/bin/test.rs b/tests/nrf51422/src/bin/test.rs
new file mode 100644
index 000000000..591bfbccc
--- /dev/null
+++ b/tests/nrf51422/src/bin/test.rs
@@ -0,0 +1,15 @@
+#![no_std]
+#![no_main]
+teleprobe_meta::target!(b"nrf51-dk");
+
+use defmt::{assert, info};
+use embassy_executor::Spawner;
+use embassy_time::{Instant, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let _p = embassy_nrf::init(Default::default());
+    info!("Test OK");
+    cortex_m::asm::bkpt();
+}

From 7c21178e378c888963150b879fc9d51684872f9e Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Fri, 26 Jan 2024 08:14:11 +0100
Subject: [PATCH 22/27] fix warnings

---
 tests/nrf51422/src/bin/test.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tests/nrf51422/src/bin/test.rs b/tests/nrf51422/src/bin/test.rs
index 591bfbccc..d3ffe26e3 100644
--- a/tests/nrf51422/src/bin/test.rs
+++ b/tests/nrf51422/src/bin/test.rs
@@ -2,9 +2,8 @@
 #![no_main]
 teleprobe_meta::target!(b"nrf51-dk");
 
-use defmt::{assert, info};
+use defmt::info;
 use embassy_executor::Spawner;
-use embassy_time::{Instant, Timer};
 use {defmt_rtt as _, panic_probe as _};
 
 #[embassy_executor::main]

From 4d8043cade887ecdc8a42e0b9bd9d3b5bcee1dbb Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Fri, 26 Jan 2024 08:39:50 +0100
Subject: [PATCH 23/27] assert only at least time slept

Cannot deterministically guarantee the upper bound
---
 tests/nrf51422/src/bin/timer.rs | 1 -
 tests/nrf52840/src/bin/timer.rs | 1 -
 2 files changed, 2 deletions(-)

diff --git a/tests/nrf51422/src/bin/timer.rs b/tests/nrf51422/src/bin/timer.rs
index 93f4c2b1c..cf9ea41a8 100644
--- a/tests/nrf51422/src/bin/timer.rs
+++ b/tests/nrf51422/src/bin/timer.rs
@@ -18,7 +18,6 @@ async fn main(_spawner: Spawner) {
     let ms = (end - start).as_millis();
     info!("slept for {} ms", ms);
     assert!(ms >= 99);
-    assert!(ms < 110);
 
     info!("Test OK");
     cortex_m::asm::bkpt();
diff --git a/tests/nrf52840/src/bin/timer.rs b/tests/nrf52840/src/bin/timer.rs
index 2a147e7ba..117947a94 100644
--- a/tests/nrf52840/src/bin/timer.rs
+++ b/tests/nrf52840/src/bin/timer.rs
@@ -18,7 +18,6 @@ async fn main(_spawner: Spawner) {
     let ms = (end - start).as_millis();
     info!("slept for {} ms", ms);
     assert!(ms >= 99);
-    assert!(ms < 110);
 
     info!("Test OK");
     cortex_m::asm::bkpt();

From ee90ee185c150085ee59c873e016b6f88f646b56 Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Fri, 26 Jan 2024 08:58:23 +0100
Subject: [PATCH 24/27] fix: link nrf51 tests from flash for now

---
 tests/nrf51422/Cargo.toml | 4 ++--
 tests/nrf51422/build.rs   | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tests/nrf51422/Cargo.toml b/tests/nrf51422/Cargo.toml
index 246b71117..2cab20ac0 100644
--- a/tests/nrf51422/Cargo.toml
+++ b/tests/nrf51422/Cargo.toml
@@ -8,9 +8,9 @@ license = "MIT OR Apache-2.0"
 teleprobe-meta = "1"
 
 embassy-sync = { version = "0.5.0", path = "../../embassy-sync", features = ["defmt", ] }
-embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["arch-cortex-m", "executor-thread", "defmt", "task-arena-size-4096", "integrated-timers"] }
+embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["arch-cortex-m", "executor-thread", "defmt", "task-arena-size-128", "integrated-timers"] }
 embassy-time = { version = "0.3.0", path = "../../embassy-time", features = ["defmt",  "defmt-timestamp-uptime"] }
-embassy-nrf = { version = "0.1.0", path = "../../embassy-nrf", features = ["defmt",  "nrf51", "time-driver-rtc1", "unstable-pac"] }
+embassy-nrf = { version = "0.1.0", path = "../../embassy-nrf", features = ["defmt",  "nrf51", "time-driver-rtc1", "unstable-pac", "time"] }
 embedded-io-async = { version = "0.6.1", features = ["defmt-03"] }
 embedded-hal-async = { version = "1.0" }
 
diff --git a/tests/nrf51422/build.rs b/tests/nrf51422/build.rs
index 71c82a70f..13ebbe4ee 100644
--- a/tests/nrf51422/build.rs
+++ b/tests/nrf51422/build.rs
@@ -4,12 +4,12 @@ use std::{env, fs};
 
 fn main() -> Result<(), Box<dyn Error>> {
     let out = PathBuf::from(env::var("OUT_DIR").unwrap());
-    fs::write(out.join("link_ram.x"), include_bytes!("../link_ram_cortex_m.x")).unwrap();
+    fs::write(out.join("memory.x"), include_bytes!("memory.x")).unwrap();
     println!("cargo:rustc-link-search={}", out.display());
-    println!("cargo:rerun-if-changed=link_ram.x");
+    println!("cargo:rerun-if-changed=memory.x");
 
     println!("cargo:rustc-link-arg-bins=--nmagic");
-    println!("cargo:rustc-link-arg-bins=-Tlink_ram.x");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
     println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
     println!("cargo:rustc-link-arg-bins=-Tteleprobe.x");
 

From 0bd9a2f09434c5c67088bce79597c581a900adeb Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Fri, 26 Jan 2024 09:03:08 +0100
Subject: [PATCH 25/27] fix gpio test and remove dummy

---
 tests/nrf51422/src/bin/gpio.rs |  4 ++--
 tests/nrf51422/src/bin/test.rs | 14 --------------
 2 files changed, 2 insertions(+), 16 deletions(-)
 delete mode 100644 tests/nrf51422/src/bin/test.rs

diff --git a/tests/nrf51422/src/bin/gpio.rs b/tests/nrf51422/src/bin/gpio.rs
index 6c6bc0839..0e5712273 100644
--- a/tests/nrf51422/src/bin/gpio.rs
+++ b/tests/nrf51422/src/bin/gpio.rs
@@ -16,11 +16,11 @@ async fn main(_spawner: Spawner) {
     let mut output = Output::new(p.P0_14, Level::Low, OutputDrive::Standard);
 
     output.set_low();
-    Timer::after_millis(1).await;
+    Timer::after_millis(10).await;
     assert!(input.is_low());
 
     output.set_high();
-    Timer::after_millis(1).await;
+    Timer::after_millis(10).await;
     assert!(input.is_high());
 
     info!("Test OK");
diff --git a/tests/nrf51422/src/bin/test.rs b/tests/nrf51422/src/bin/test.rs
deleted file mode 100644
index d3ffe26e3..000000000
--- a/tests/nrf51422/src/bin/test.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-#![no_std]
-#![no_main]
-teleprobe_meta::target!(b"nrf51-dk");
-
-use defmt::info;
-use embassy_executor::Spawner;
-use {defmt_rtt as _, panic_probe as _};
-
-#[embassy_executor::main]
-async fn main(_spawner: Spawner) {
-    let _p = embassy_nrf::init(Default::default());
-    info!("Test OK");
-    cortex_m::asm::bkpt();
-}

From bea3c5495a37481c85bcfce8d55f94049e4b89fd Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Fri, 26 Jan 2024 09:05:58 +0100
Subject: [PATCH 26/27] use pull-up to ensure we assert the correct change

---
 tests/nrf51422/src/bin/gpio.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/nrf51422/src/bin/gpio.rs b/tests/nrf51422/src/bin/gpio.rs
index 0e5712273..6d5a87d0a 100644
--- a/tests/nrf51422/src/bin/gpio.rs
+++ b/tests/nrf51422/src/bin/gpio.rs
@@ -12,7 +12,7 @@ use {defmt_rtt as _, panic_probe as _};
 async fn main(_spawner: Spawner) {
     let p = embassy_nrf::init(Default::default());
 
-    let input = Input::new(p.P0_13, Pull::None);
+    let input = Input::new(p.P0_13, Pull::Up);
     let mut output = Output::new(p.P0_14, Level::Low, OutputDrive::Standard);
 
     output.set_low();

From 531645e5d4650c87df5c0a3e2603a43ee9049f7b Mon Sep 17 00:00:00 2001
From: Ulf Lilleengen <ulf.lilleengen@gmail.com>
Date: Fri, 26 Jan 2024 09:11:17 +0100
Subject: [PATCH 27/27] docs: mention nrf51

---
 embassy-nrf/README.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/embassy-nrf/README.md b/embassy-nrf/README.md
index 50662749d..3df5f1fa5 100644
--- a/embassy-nrf/README.md
+++ b/embassy-nrf/README.md
@@ -14,11 +14,12 @@ For a complete list of available peripherals and features, see the [embassy-nrf
 
 The `embassy-nrf` HAL supports most variants of the nRF family:
 
+* nRF51 ([examples](https://github.com/embassy-rs/embassy/tree/main/examples/nrf51))
 * nRF52 ([examples](https://github.com/embassy-rs/embassy/tree/main/examples/nrf52840))
 * nRF53 ([examples](https://github.com/embassy-rs/embassy/tree/main/examples/nrf5340))
 * nRF91 ([examples](https://github.com/embassy-rs/embassy/tree/main/examples/nrf9160))
 
-Most peripherals are supported. To check what's available, make sure to pick the MCU you're targeting in the top menu in the [documentation](https://docs.embassy.dev/embassy-nrf).
+Most peripherals are supported, but can vary between chip families. To check what's available, make sure to pick the MCU you're targeting in the top menu in the [documentation](https://docs.embassy.dev/embassy-nrf).
 
 For MCUs with TrustZone support, both Secure (S) and Non-Secure (NS) modes are supported. Running in Secure mode
 allows running Rust code without a SPM or TF-M binary, saving flash space and simplifying development.