korg-kaoss-dj: Send MIDI reset messages on attach/detach

Cargo.toml

@@ -22,7 +22,7 @@ futures = "0.3.28"
 is_sorted = "0.1.1"
 log = "0.4.20"
 strum = { version = "0.25.0", features = ["derive"] }
-thiserror = "1.0.47"
+thiserror = "1.0.48"
 
 # Optional dependencies
 discro = { version = "0.15.0", optional = true }

src/devices/korg_kaoss_dj/output.rs

@@ -203,7 +203,9 @@ fn on_attach<C: MidiOutputConnection>(midi_output_connection: &mut C) -> OutputR
     const MIDI_STATUS_SYSEX: &[u8] = &[
         0xf0, 0x42, 0x40, 0x00, 0x01, 0x28, 0x00, 0x1f, 0x70, 0x01, 0xf7,
     ];
-    midi_output_connection.send_midi_output(MIDI_STATUS_SYSEX)?;
+    // First send a MIDI system reset message
+    midi_output_connection.send_midi_system_reset()?;
+    // Turn on all knob LEDs
     for led in MainLed::iter() {
         let output = if led.is_knob() {
             LedOutput::On
@@ -222,10 +224,15 @@ fn on_attach<C: MidiOutputConnection>(midi_output_connection: &mut C) -> OutputR
             send_led_output(midi_output_connection, Led::Deck(deck, led), output)?;
         }
     }
+    // Finally query the initial position of all knobs and faders
+    midi_output_connection.send_midi_output(MIDI_STATUS_SYSEX)?;
     Ok(())
 }
 
 fn on_detach<C: MidiOutputConnection>(midi_output_connection: &mut C) -> OutputResult<()> {
+    // First send a MIDI system reset message
+    midi_output_connection.send_midi_system_reset()?;
+    // Turn off all LEDs
     for led in MainLed::iter() {
         send_led_output(midi_output_connection, led.into(), LedOutput::Off)?;
     }

src/midi/mod.rs

@@ -14,6 +14,8 @@ use crate::{
 #[cfg(feature = "midir")]
 pub(crate) mod midir;
 
+const MIDI_OUTPUT_SYSTEM_RESET: &[u8] = &[0xff];
+
 /// MIDI-related, extended [`DeviceDescriptor`]
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct MidiDeviceDescriptor {
@@ -124,6 +126,10 @@ where
 
 pub trait MidiOutputConnection {
     fn send_midi_output(&mut self, output: &[u8]) -> OutputResult<()>;
+
+    fn send_midi_system_reset(&mut self) -> OutputResult<()> {
+        self.send_midi_output(MIDI_OUTPUT_SYSTEM_RESET)
+    }
 }
 
 pub type BoxedMidiOutputConnection = Box<dyn MidiOutputConnection + Send + 'static>;

src/output/blinking_led_task.rs

@@ -16,6 +16,7 @@ pub fn blinking_led_task(
         let mut ticker = BlinkingLedTicker::default();
         let mut interval = tokio::time::interval(period);
         loop {
+            // The first tick arrives immediately
             interval.tick().await;
             let output = ticker.tick();
             publisher.write(output);