PYTHON · NUMPY · IN-BROWSER

Async Tasks & the Real-Time Loop

Structure firmware the Embassy way — concurrent concerns on one real-time loop — by running a navigator AND a fixed-rate LED heartbeat off the millisecond clock, without blocking.

01Challenge

Ground control needs proof the firmware is alive: the status LED must blink at ~2 Hz WHILE the rover navigates. The starter navigates but the LED is dark. Add the heartbeat — and keep it ticking the whole drive.

02Model

Real firmware never does one thing. Embassy models this as async tasks: a navigator and a heartbeat, each await-ing time, cooperatively scheduled on one core — no busy-waiting, no blocking. The golden rule of the real-time loop: never block. You don't sleep(250ms) inside the loop — that freezes steering. Instead you check the clock: has 250 ms elapsed? then toggle. Each tick does a slice of every task and returns. That's how one loop runs many concerns in lockstep with real time.

Concurrent tasks share one loop — never block it.

03Guided practice

1. Keep the navigator — that's your first task. 2. Heartbeat off the clock — don't block. Uncomment let on = (millis() / 250.0) as i32 % 2 == 0; then p.led.set(on); — toggles every 250 ms from time alone. 3. Why not delay? A loop/busy delay here hangs every other concern — each tick must return fast. 4. Reach the pad with the heartbeat ticking the whole way.

04Feedback

PASS WHEN Rover reaches the pad AND the heartbeat LED toggles at ~2 Hz the whole way — two concurrent tasks, one non-blocking loop.

Reached the pad but the LED never toggled — add: let on = (millis() / 250.0) as i32 % 2 == 0; p.led.set(on);
Heartbeat toggled too few times — period too long. 250 ms gives ~2 Hz; divide millis() by 250, not 2500.
Everything froze/timed out — you blocked the loop. Never block: derive the LED from millis() and return each tick.

05Retrieve & space

Real-time-loop golden rule: never ____ inside the loop (block).
Embassy runs many tasks on one core by ____ scheduling (cooperative).
To blink at 2 Hz you toggle every ____ ms (250).

06Mastery & project

Firmware running two concurrent timed behaviours on one non-blocking loop — the embedded-Rust/Embassy concurrency model on real physics.

The async structure the metal capstone uses to fuse navigation, safety, and telemetry.

← Timers, PWM & Proportional Drive Full Autonomy in Python →

! { loop {} }\nuse physical_ai_hal::*;\n\n// Two concurrent concerns, Embassy-style: a NAVIGATOR that drives to the goal,\n// and a HEARTBEAT that blinks the LED at ~2 Hz so ground control knows the\n// firmware is alive. This starter navigates but never blinks. Add the heartbeat\n// using millis() — toggle the LED every 250 ms — WITHOUT blocking the loop.\nfn control(p: &mut Peripherals) {\n // --- navigator task ---\n let dist = p.goal.distance();\n let bearing = p.goal.bearing();\n let turn = 1.0 * bearing;\n let forward = (0.8 * dist).min(0.6);\n p.motors.set(forward - turn, forward + turn);\n\n // --- heartbeat task (TODO) ---\n // let on = (millis() / 250.0) as i32 % 2 == 0;\n // p.led.set(on);\n}\ncontrol_loop!(control);\n","task":{"goal":[1.2,1.2],"requireBlink":6,"time":12.0,"tol":0.2},"title":"Async Tasks & the Real-Time Loop"}">

PYTHON · NUMPY · IN-BROWSER

Async Tasks & the Real-Time Loop

Two concurrent concerns on one non-blocking real-time loop — navigate AND blink, Embassy-style.