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-rw-r--r--book/en/archive/by_example/app_task.md23
-rw-r--r--book/en/archive/by_example/monotonic.md64
-rw-r--r--book/en/archive/by_example/tips/from_ram.md45
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diff --git a/book/en/archive/by_example/app_task.md b/book/en/archive/by_example/app_task.md
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+<!-- Should probably be removed -->
+
+# Defining tasks with `#[task]`
+
+Tasks, defined with `#[task]`, are the main mechanism of getting work done in RTIC.
+
+Tasks can
+
+* Be spawned (now or in the future, also by themselves)
+* Receive messages (passing messages between tasks)
+* Be prioritized, allowing preemptive multitasking
+* Optionally bind to a hardware interrupt
+
+RTIC makes a distinction between “software tasks” and “hardware tasks”.
+
+*Hardware tasks* are tasks that are bound to a specific interrupt vector in the MCU while software tasks are not.
+
+This means that if a hardware task is bound to, lets say, a UART RX interrupt, the task will be run every
+time that interrupt triggers, usually when a character is received.
+
+*Software tasks* are explicitly spawned in a task, either immediately or using the Monotonic timer mechanism.
+
+In the coming pages we will explore both tasks and the different options available.
diff --git a/book/en/archive/by_example/monotonic.md b/book/en/archive/by_example/monotonic.md
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+# Monotonic & spawn_{at/after}
+
+The understanding of time is an important concept in embedded systems, and to be able to run tasks
+based on time is essential. The framework provides the static methods
+`task::spawn_after(/* duration */)` and `task::spawn_at(/* specific time instant */)`.
+`spawn_after` is more commonly used, but in cases where it's needed to have spawns happen
+without drift or to a fixed baseline `spawn_at` is available.
+
+The `#[monotonic]` attribute, applied to a type alias definition, exists to support this.
+This type alias must point to a type which implements the [`rtic_monotonic::Monotonic`] trait.
+This is generally some timer which handles the timing of the system.
+One or more monotonics can coexist in the same system, for example a slow timer that wakes the
+system from sleep and another which purpose is for fine grained scheduling while the
+system is awake.
+
+[`rtic_monotonic::Monotonic`]: https://docs.rs/rtic-monotonic
+
+The attribute has one required parameter and two optional parameters, `binds`, `default` and
+`priority` respectively.
+The required parameter, `binds = InterruptName`, associates an interrupt vector to the timer's
+interrupt, while `default = true` enables a shorthand API when spawning and accessing
+time (`monotonics::now()` vs `monotonics::MyMono::now()`), and `priority` sets the priority
+of the interrupt vector.
+
+> The default `priority` is the **maximum priority** of the system.
+> If your system has a high priority task with tight scheduling requirements,
+> it might be desirable to demote the `monotonic` task to a lower priority
+> to reduce scheduling jitter for the high priority task.
+> This however might introduce jitter and delays into scheduling via the `monotonic`,
+> making it a trade-off.
+
+The monotonics are initialized in `#[init]` and returned within the `init::Monotonic( ... )` tuple.
+This activates the monotonics making it possible to use them.
+
+See the following example:
+
+``` rust,noplayground
+{{#include ../../../../examples/schedule.rs}}
+```
+
+``` console
+$ cargo run --target thumbv7m-none-eabi --example schedule
+{{#include ../../../../ci/expected/schedule.run}}
+```
+
+A key requirement of a Monotonic is that it must deal gracefully with
+hardware timer overruns.
+
+## Canceling or rescheduling a scheduled task
+
+Tasks spawned using `task::spawn_after` and `task::spawn_at` returns a `SpawnHandle`,
+which allows canceling or rescheduling of the task scheduled to run in the future.
+
+If `cancel` or `reschedule_at`/`reschedule_after` returns an `Err` it means that the operation was
+too late and that the task is already sent for execution. The following example shows this in action:
+
+``` rust,noplayground
+{{#include ../../../../examples/cancel-reschedule.rs}}
+```
+
+``` console
+$ cargo run --target thumbv7m-none-eabi --example cancel-reschedule
+{{#include ../../../../ci/expected/cancel-reschedule.run}}
+```
diff --git a/book/en/archive/by_example/tips/from_ram.md b/book/en/archive/by_example/tips/from_ram.md
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+# Running tasks from RAM
+
+The main goal of moving the specification of RTIC applications to attributes in RTIC v0.4.0 was to allow inter-operation with other attributes. For example, the `link_section` attribute can be applied to tasks to place them in RAM; this can
+improve performance in some cases.
+
+> **IMPORTANT**: In general, the `link_section`, `export_name` and `no_mangle` attributes are powerful but also easy to misuse. Incorrectly using any of these attributes can cause undefined behavior; you should always prefer to use safe, higher level attributes around them like `cortex-m-rt`'s `interrupt` and `exception` attributes.
+>
+> In the particular case of RAM functions there's no safe abstraction for it in `cortex-m-rt` v0.6.5 but there's an [RFC] for adding a `ramfunc` attribute in a future release.
+
+[RFC]: https://github.com/rust-embedded/cortex-m-rt/pull/100
+
+The example below shows how to place the higher priority task, `bar`, in RAM.
+
+``` rust,noplayground
+{{#include ../../../../../rtic/examples/ramfunc.rs}}
+```
+
+Running this program produces the expected output.
+
+``` console
+$ cargo run --target thumbv7m-none-eabi --example ramfunc
+```
+
+``` console
+{{#include ../../../../../rtic/ci/expected/ramfunc.run}}
+```
+
+One can look at the output of `cargo-nm` to confirm that `bar` ended in RAM
+(`0x2000_0000`), whereas `foo` ended in Flash (`0x0000_0000`).
+
+``` console
+$ cargo nm --example ramfunc --release | grep ' foo::'
+```
+
+``` console
+{{#include ../../../../../rtic/ci/expected/ramfunc.run.grep.foo}}
+```
+
+``` console
+$ cargo nm --example ramfunc --target thumbv7m-none-eabi --release | grep '*bar::'
+```
+
+``` console
+{{#include ../../../../../rtic/ci/expected/ramfunc.run.grep.bar}}
+```