working everything properly well

mqtt_display/src/display/api.rs

@@ -0,0 +1,81 @@
+// src/display/api.rs
+//! Public API for the display feature.
+//!
+//! Other parts of the system use this module to send commands to the display.
+//! The actual rendering happens in `task.rs`.
+
+use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+use embassy_sync::channel::{Channel, Receiver, TrySendError};
+use heapless::String as HString;
+
+use crate::contracts::{DisplayCommand, ImuReading};
+
+/// Queue size for display commands.
+/// Moderate size to handle bursts without dropping.
+const QUEUE_SIZE: usize = 8;
+
+/// Channel for sending commands to the display task.
+pub(crate) static DISPLAY_CHANNEL: Channel<CriticalSectionRawMutex, DisplayCommand, QUEUE_SIZE> =
+    Channel::new();
+
+/// Send a command to the display.
+///
+/// This is async and will wait if the queue is full.
+/// For fire-and-forget, use `try_send`.
+///
+/// # Example
+/// ```ignore
+/// display::api::send(DisplayCommand::SetStatus("Hello".try_into().unwrap())).await;
+/// ```
+pub async fn send(cmd: DisplayCommand) {
+    DISPLAY_CHANNEL.send(cmd).await;
+}
+
+/// Try to send a command without waiting.
+///
+/// Returns `Err(cmd)` if the queue is full.
+pub fn try_send(cmd: DisplayCommand) -> Result<(), DisplayCommand> {
+    DISPLAY_CHANNEL.try_send(cmd).map_err(|e| match e {
+        TrySendError::Full(command) => command,
+    })
+}
+
+/// Get a receiver for display commands (internal use).
+///
+/// Used by the display task to receive commands.
+pub(crate) fn receiver() -> Receiver<'static, CriticalSectionRawMutex, DisplayCommand, QUEUE_SIZE> {
+    DISPLAY_CHANNEL.receiver()
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// Convenience functions for common commands
+// ─────────────────────────────────────────────────────────────────────────────
+
+/// Send IMU data to the display.
+pub async fn show_imu(reading: ImuReading) {
+    send(DisplayCommand::SetImu(reading)).await;
+}
+
+/// Set the status line.
+pub async fn set_status(text: &str) {
+    let mut s = HString::<32>::new();
+    let _ = s.push_str(&text[..text.len().min(32)]);
+    send(DisplayCommand::SetStatus(s)).await;
+}
+
+/// Show an error message.
+pub async fn show_error(text: &str) {
+    let mut s = HString::<64>::new();
+    let _ = s.push_str(&text[..text.len().min(64)]);
+    send(DisplayCommand::ShowError(s)).await;
+}
+
+/// Update MQTT status indicator.
+pub async fn set_mqtt_status(connected: bool, msg_count: u32) {
+    send(DisplayCommand::SetMqttStatus { connected, msg_count }).await;
+}
+
+/// Clear the display.
+pub async fn clear() {
+    send(DisplayCommand::Clear).await;
+}