Start async tasks at lowest priority

rtic-macros/src/syntax/parse.rs

@@ -289,11 +289,13 @@ fn task_args(tokens: TokenStream2) -> parse::Result<Either<HardwareTaskArgs, Sof
             // Handle comma: ,
             let _: Token![,] = content.parse()?;
         }
-        let priority = priority.unwrap_or(1);
         let shared_resources = shared_resources.unwrap_or_default();
         let local_resources = local_resources.unwrap_or_default();
 
         Ok(if let Some(binds) = binds {
+            // Hardware tasks can't run at anything lower than 1
+            let priority = priority.unwrap_or(1);
+
             if priority == 0 {
                 return Err(parse::Error::new(
                     prio_span.unwrap(),
@@ -308,6 +310,9 @@ fn task_args(tokens: TokenStream2) -> parse::Result<Either<HardwareTaskArgs, Sof
                 local_resources,
             })
         } else {
+            // Software tasks start at idle priority
+            let priority = priority.unwrap_or(0);
+
             Either::Right(SoftwareTaskArgs {
                 priority,
                 shared_resources,

rtic/CHANGELOG.md

@@ -13,6 +13,8 @@ For each category, *Added*, *Changed*, *Fixed* add new entries at the top!
 
 ### Changed
 
+- Make async task priorities start at 0, instead of 1, to always start at the lowest priority
+
 ## [v1.1.4] - 2023-02-26
 
 ### Added

rtic/examples/async-task.rs

@@ -53,13 +53,13 @@ mod app {
         hprintln!("hello from hw");
     }
 
-    #[task(shared = [a])]
+    #[task(shared = [a], priority = 1)]
     async fn async_task(cx: async_task::Context) {
         let async_task::SharedResources { a: _, .. } = cx.shared;
         hprintln!("hello from async");
     }
 
-    #[task]
+    #[task(priority = 1)]
     async fn async_task_args(_cx: async_task_args::Context, a: u32, b: i32) {
         hprintln!("hello from async with args a: {}, b: {}", a, b);
     }

rtic/examples/common.rs

@@ -62,7 +62,7 @@ mod app {
     }
 
     // `local_to_foo` can only be accessed from this context
-    #[task(local = [local_to_foo])]
+    #[task(local = [local_to_foo], priority = 1)]
     async fn foo(cx: foo::Context) {
         let local_to_foo = cx.local.local_to_foo;
         *local_to_foo += 1;
@@ -74,7 +74,7 @@ mod app {
     }
 
     // `local_to_bar` can only be accessed from this context
-    #[task(local = [local_to_bar])]
+    #[task(local = [local_to_bar], priority = 1)]
     async fn bar(cx: bar::Context) {
         let local_to_bar = cx.local.local_to_bar;
         *local_to_bar += 1;

rtic/examples/destructure.rs

@@ -38,7 +38,7 @@ mod app {
     }
 
     // Direct destructure
-    #[task(shared = [&a, &b, &c])]
+    #[task(shared = [&a, &b, &c], priority = 1)]
     async fn foo(cx: foo::Context) {
         let a = cx.shared.a;
         let b = cx.shared.b;
@@ -48,7 +48,7 @@ mod app {
     }
 
     // De-structure-ing syntax
-    #[task(shared = [&a, &b, &c])]
+    #[task(shared = [&a, &b, &c], priority = 1)]
     async fn bar(cx: bar::Context) {
         let bar::SharedResources { a, b, c, .. } = cx.shared;
 

rtic/examples/locals.rs

@@ -62,7 +62,7 @@ mod app {
     }
 
     // `local_to_foo` can only be accessed from this context
-    #[task(local = [local_to_foo])]
+    #[task(local = [local_to_foo], priority = 1)]
     async fn foo(cx: foo::Context) {
         let local_to_foo = cx.local.local_to_foo;
         *local_to_foo += 1;
@@ -74,7 +74,7 @@ mod app {
     }
 
     // `local_to_bar` can only be accessed from this context
-    #[task(local = [local_to_bar])]
+    #[task(local = [local_to_bar], priority = 1)]
     async fn bar(cx: bar::Context) {
         let local_to_bar = cx.local.local_to_bar;
         *local_to_bar += 1;

rtic/examples/not-sync.rs

@@ -54,13 +54,13 @@ mod app {
         loop {}
     }
 
-    #[task(shared = [&shared])]
+    #[task(shared = [&shared], priority = 1)]
     async fn foo(c: foo::Context) {
         let shared: &NotSync = c.shared.shared;
         hprintln!("foo a {}", shared.data);
     }
 
-    #[task(shared = [&shared])]
+    #[task(shared = [&shared], priority = 1)]
     async fn bar(c: bar::Context) {
         let shared: &NotSync = c.shared.shared;
         hprintln!("bar a {}", shared.data);

rtic/examples/static.rs

@@ -51,7 +51,7 @@ mod app {
         }
     }
 
-    #[task(local = [p, state: u32 = 0])]
+    #[task(local = [p, state: u32 = 0], priority = 1)]
     async fn foo(c: foo::Context) {
         *c.local.state += 1;