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diff --git a/book/en/src/migration/migration_v4.md b/book/en/src/migration/migration_v4.md new file mode 100644 index 00000000..ac59d8c9 --- /dev/null +++ b/book/en/src/migration/migration_v4.md @@ -0,0 +1,233 @@ +# Migrating from v0.4.x to v0.5.0 + +This section covers how to upgrade an application written against RTIC v0.4.x to +the version v0.5.0 of the framework. + +## `Cargo.toml` + +First, the version of the `cortex-m-rtic` dependency needs to be updated to +`"0.5.0"`. The `timer-queue` feature needs to be removed. + +``` toml +[dependencies.cortex-m-rtic] +# change this +version = "0.4.3" + +# into this +version = "0.5.0" + +# and remove this Cargo feature +features = ["timer-queue"] +# ^^^^^^^^^^^^^ +``` + +## `Context` argument + +All functions inside the `#[rtic::app]` item need to take as first argument a +`Context` structure. This `Context` type will contain the variables that were +magically injected into the scope of the function by version v0.4.x of the +framework: `resources`, `spawn`, `schedule` -- these variables will become +fields of the `Context` structure. Each function within the `#[rtic::app]` item +gets a different `Context` type. + +``` rust +#[rtic::app(/* .. */)] +const APP: () = { + // change this + #[task(resources = [x], spawn = [a], schedule = [b])] + fn foo() { + resources.x.lock(|x| /* .. */); + spawn.a(message); + schedule.b(baseline); + } + + // into this + #[task(resources = [x], spawn = [a], schedule = [b])] + fn foo(mut cx: foo::Context) { + // ^^^^^^^^^^^^^^^^^^^^ + + cx.resources.x.lock(|x| /* .. */); + // ^^^ + + cx.spawn.a(message); + // ^^^ + + cx.schedule.b(message, baseline); + // ^^^ + } + + // change this + #[init] + fn init() { + // .. + } + + // into this + #[init] + fn init(cx: init::Context) { + // ^^^^^^^^^^^^^^^^^ + // .. + } + + // .. +}; +``` + +## Resources + +The syntax used to declare resources has been changed from `static mut` +variables to a `struct Resources`. + +``` rust +#[rtic::app(/* .. */)] +const APP: () = { + // change this + static mut X: u32 = 0; + static mut Y: u32 = (); // late resource + + // into this + struct Resources { + #[init(0)] // <- initial value + X: u32, // NOTE: we suggest changing the naming style to `snake_case` + + Y: u32, // late resource + } + + // .. +}; +``` + +## Device peripherals + +If your application was accessing the device peripherals in `#[init]` through +the `device` variable then you'll need to add `peripherals = true` to the +`#[rtic::app]` attribute to continue to access the device peripherals through +the `device` field of the `init::Context` structure. + +Change this: + +``` rust +#[rtic::app(/* .. */)] +const APP: () = { + #[init] + fn init() { + device.SOME_PERIPHERAL.write(something); + } + + // .. +}; +``` + +Into this: + +``` rust +#[rtic::app(/* .. */, peripherals = true)] +// ^^^^^^^^^^^^^^^^^^ +const APP: () = { + #[init] + fn init(cx: init::Context) { + // ^^^^^^^^^^^^^^^^^ + cx.device.SOME_PERIPHERAL.write(something); + // ^^^ + } + + // .. +}; +``` + +## `#[interrupt]` and `#[exception]` + +The `#[interrupt]` and `#[exception]` attributes have been removed. To declare +hardware tasks in v0.5.x use the `#[task]` attribute with the `binds` argument. + +Change this: + +``` rust +#[rtic::app(/* .. */)] +const APP: () = { + // hardware tasks + #[exception] + fn SVCall() { /* .. */ } + + #[interrupt] + fn UART0() { /* .. */ } + + // software task + #[task] + fn foo() { /* .. */ } + + // .. +}; +``` + +Into this: + +``` rust +#[rtic::app(/* .. */)] +const APP: () = { + #[task(binds = SVCall)] + // ^^^^^^^^^^^^^^ + fn svcall(cx: svcall::Context) { /* .. */ } + // ^^^^^^ we suggest you use a `snake_case` name here + + #[task(binds = UART0)] + // ^^^^^^^^^^^^^ + fn uart0(cx: uart0::Context) { /* .. */ } + + #[task] + fn foo(cx: foo::Context) { /* .. */ } + + // .. +}; +``` + +## `schedule` + +The `schedule` API no longer requires the `timer-queue` cargo feature, which has +been removed. To use the `schedule` API one must +first define the monotonic timer the runtime will use using the `monotonic` +argument of the `#[rtic::app]` attribute. To continue using the cycle counter +(CYCCNT) as the monotonic timer, and match the behavior of version v0.4.x, add +the `monotonic = rtic::cyccnt::CYCCNT` argument to the `#[rtic::app]` attribute. + +Also, the `Duration` and `Instant` types and the `U32Ext` trait have been moved +into the `rtic::cyccnt` module. This module is only available on ARMv7-M+ +devices. The removal of the `timer-queue` also brings back the `DWT` peripheral +inside the core peripherals struct, this will need to be enabled by the application +inside `init`. + +Change this: + +``` rust +use rtic::{Duration, Instant, U32Ext}; + +#[rtic::app(/* .. */)] +const APP: () = { + #[task(schedule = [b])] + fn a() { + // .. + } +}; +``` + +Into this: + +``` rust +use rtic::cyccnt::{Duration, Instant, U32Ext}; +// ^^^^^^^^ + +#[rtic::app(/* .. */, monotonic = rtic::cyccnt::CYCCNT)] +// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +const APP: () = { + #[init] + fn init(cx: init::Context) { + cx.core.DWT.enable_cycle_counter(); + // optional, configure the DWT run without a debugger connected + cx.core.DCB.enable_trace(); + } + #[task(schedule = [b])] + fn a(cx: a::Context) { + // .. + } +}; +``` |