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Diffstat (limited to 'book/en/src/by-example/software_tasks.md')
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1 files changed, 19 insertions, 15 deletions
diff --git a/book/en/src/by-example/software_tasks.md b/book/en/src/by-example/software_tasks.md index 5c03f91..8ee185b 100644 --- a/book/en/src/by-example/software_tasks.md +++ b/book/en/src/by-example/software_tasks.md @@ -2,29 +2,33 @@ The RTIC concept of a software task shares a lot with that of [hardware tasks](./hardware_tasks.md) with the core difference that a software task is not explicitly bound to a specific -interrupt vector, but rather a “dispatcher” interrupt vector running -at the same priority as the software task. +interrupt vector, but rather bound to a “dispatcher” interrupt vector running +at the intended priority of the software task (see below). -Thus, software tasks are tasks which are not directly assigned to a specific interrupt vector. +Thus, software tasks are tasks which are not *directly* bound to an interrupt vector. -The `#[task]` attribute used on a function declare it as a software tasks. -Observe the absence of a `binds = InterruptName` argument to the attribute. -The static method `task_name::spawn()` spawns (starts) a software task and -given that there are no higher priority tasks running the task will start executing directly. +The `#[task]` attributes used on a function determine if it is +software tasks, specifically the absence of a `binds = InterruptName` +argument to the attribute definition. -All software tasks at the same priority level shares an interrupt handler acting as a dispatcher. -What differentiates software and hardware tasks are the dispatcher versus bound interrupt vector. +The static method `task_name::spawn()` spawns (schedules) a software +task by registering it with a specific dispatcher. If there are no +higher priority tasks available to the scheduler (which serves a set +of dispatchers), the task will start executing directly. -The interrupt vectors used as dispatchers can not be used by hardware tasks. +All software tasks at the same priority level share an interrupt handler bound to their dispatcher. +What differentiates software and hardware tasks is the usage of either a dispatcher or a bound interrupt vector. -A list of “free” (not in use by hardware tasks) and usable interrupts allows the framework -to dispatch software tasks. +The interrupt vectors used as dispatchers cannot be used by hardware tasks. -This list of dispatchers, `dispatchers = [FreeInterrupt1, FreeInterrupt2, ...]` is an +Availability of a set of “free” (not in use by hardware tasks) and usable interrupt vectors allows the framework +to dispatch software tasks via dedicated interrupt handlers. + +This set of dispatchers, `dispatchers = [FreeInterrupt1, FreeInterrupt2, ...]` is an argument to the `#[app]` attribute. -Each interrupt vector acting as dispatcher gets assigned to one priority level meaning that -the list of dispatchers need to cover all priority levels used by software tasks. +Each interrupt vector acting as dispatcher gets assigned to a unique priority level meaning that +the list of dispatchers needs to cover all priority levels used by software tasks. Example: The `dispatchers =` argument needs to have at least 3 entries for an application using three different priorities for software tasks. |