Change back to 10ms polling

rp2040/src/hardware.rs

@@ -35,7 +35,8 @@ pub mod usb {
 /// Timing cadence helpers used throughout the firmware.
 pub mod timers {
     pub const USB_REPORT_INTERVAL_MS: u32 = 10;
-    pub const USB_TICK_INTERVAL_US: u32 = 250;
+    pub const USB_TICK_INTERVAL_MS: u32 = 1;
+    pub const SCAN_TICK_INTERVAL_US: u32 = 250;
     pub const STATUS_LED_INTERVAL_MS: u32 = 10;
     pub const IDLE_TIMEOUT_MS: u32 = 5_000;
 }

rp2040/src/main.rs

@@ -60,8 +60,11 @@ fn main() -> ! {
     }
 
     // Timers driving periodic USB polls and status LED updates.
+    let mut scan_tick = timer.count_down();
+    scan_tick.start(timers::SCAN_TICK_INTERVAL_US.micros());
+
     let mut usb_tick = timer.count_down();
-    usb_tick.start(timers::USB_TICK_INTERVAL_US.micros());
+    usb_tick.start(timers::USB_TICK_INTERVAL_MS.millis());
 
     let mut status_tick = timer.count_down();
     status_tick.start(timers::STATUS_LED_INTERVAL_MS.millis());
@@ -82,10 +85,12 @@ fn main() -> ! {
             status_led.apply_summary(summary, status_time_ms);
         }
 
+        if scan_tick.wait().is_ok() {
             let should_scan = {
                 const SUSPENDED_SCAN_PERIOD: u8 = 20;
                 if keyboard_state.usb().suspended {
-                suspended_scan_counter = (suspended_scan_counter + 1) % SUSPENDED_SCAN_PERIOD;
+                    suspended_scan_counter =
+                        (suspended_scan_counter + 1) % SUSPENDED_SCAN_PERIOD;
                     suspended_scan_counter == 0
                 } else {
                     suspended_scan_counter = 0;
@@ -93,7 +98,7 @@ fn main() -> ! {
                 }
             };
 
-        if usb_tick.wait().is_ok() && should_scan {
+            if should_scan {
                 // Scan the key matrix, handle bootloader chord, and produce a report.
                 button_matrix.scan_matrix(&mut delay);
                 let pressed_keys = button_matrix.buttons_pressed();
@@ -133,7 +138,10 @@ fn main() -> ! {
                         }
                     }
                 }
+            }
+        }
 
+        if usb_tick.wait().is_ok() {
             match keyboard.tick() {
                 Err(UsbHidError::WouldBlock) | Ok(_) => {}
                 Err(_) => {

rp2040/src/status.rs

@@ -14,6 +14,7 @@ const COLOR_ORANGE: RGB8 = RGB8 { r: 5, g: 10, b: 0 };
 const COLOR_RED: RGB8 = RGB8 { r: 20, g: 0, b: 0 };
 const COLOR_PURPLE: RGB8 = RGB8 { r: 0, g: 10, b: 10 };
 const BREATH_PERIOD_MS: u32 = 3200;
+const BREATH_PAUSE_MS: u32 = 3000;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum StatusMode {
@@ -105,8 +106,9 @@ where
         let mode = summary_to_mode(summary);
         let elapsed = if self.current_mode != mode {
             self.current_mode = mode;
-            self.mode_started_at = Some(current_time_ms);
-            0
+            let start = mode_start_time(mode, current_time_ms);
+            self.mode_started_at = Some(start);
+            current_time_ms.saturating_sub(start)
         } else {
             let start = self.mode_started_at.unwrap_or(current_time_ms);
             current_time_ms.saturating_sub(start)
@@ -162,6 +164,13 @@ fn mode_color(mode: StatusMode, elapsed_ms: u32) -> RGB8 {
     }
 }
 
+fn mode_start_time(mode: StatusMode, now: u32) -> u32 {
+    match mode {
+        StatusMode::Idle => now.saturating_sub(BREATH_PERIOD_MS / 2),
+        _ => now,
+    }
+}
+
 fn blink(color: RGB8, elapsed_ms: u32, period_ms: u32) -> RGB8 {
     // Toggle between the provided colour and off at the requested period.
     if period_ms == 0 {
@@ -178,22 +187,176 @@ fn breathe(color: RGB8, elapsed_ms: u32, period_ms: u32) -> RGB8 {
     }
 
     let period = period_ms.max(1);
-    let phase = (elapsed_ms % period) as f32 / period as f32;
-    let brightness = if phase < 0.5 {
-        1.0 - (phase * 2.0)
-    } else {
-        (phase - 0.5) * 2.0
-    };
-    let brightness_factor = ((brightness.clamp(0.0, 1.0) * 255.0) + 0.5) as u8;
+    let cycle = period.saturating_add(BREATH_PAUSE_MS);
+    let phase = elapsed_ms % cycle;
+    if phase >= period {
+        return COLOR_OFF;
+    }
 
-    scale_color(color, brightness_factor)
+    let half = (period / 2).max(1);
+    let ramp = if phase < half {
+        ((phase * 255) / half) as u8
+    } else {
+        (((period - phase) * 255) / half) as u8
+    };
+
+    scale_color(color, ramp)
 }
 
 fn scale_color(color: RGB8, factor: u8) -> RGB8 {
-    // Linearly scale each colour component by the provided brightness factor.
+    // Scale components while maintaining colour balance at low brightness.
+    if factor == 0 {
+        return COLOR_OFF;
+    }
+
+    let components = [color.r, color.g, color.b];
+    let mut scaled = [0u8; 3];
+    let mut remainders = [0u16; 3];
+    let mut total_floor: u16 = 0;
+    let mut total_base: u16 = 0;
+    let factor_u16 = factor as u16;
+
+    for (index, &component) in components.iter().enumerate() {
+        total_base += component as u16;
+        if component == 0 {
+            continue;
+        }
+
+        let value = component as u32 * factor as u32;
+        let div = (value / 255) as u16;
+        let rem = (value % 255) as u16;
+
+        scaled[index] = div as u8;
+        remainders[index] = rem;
+        total_floor += div;
+    }
+
+    if total_base == 0 {
+        return COLOR_OFF;
+    }
+
+    let mut target_total = ((total_base as u32 * factor_u16 as u32) + 127) / 255;
+    if target_total > total_base as u32 {
+        target_total = total_base as u32;
+    }
+
+    let mut extra = target_total.saturating_sub(total_floor as u32) as u16;
+
+    while extra > 0 {
+        let mut best_index: Option<usize> = None;
+        let mut best_remainder = 0u16;
+
+        for idx in 0..components.len() {
+            if components[idx] == 0 {
+                continue;
+            }
+            if remainders[idx] == 0 {
+                continue;
+            }
+            if scaled[idx] as u16 >= components[idx] as u16 {
+                continue;
+            }
+
+            if remainders[idx] > best_remainder {
+                best_remainder = remainders[idx];
+                best_index = Some(idx);
+            }
+        }
+
+        let Some(idx) = best_index else {
+            break;
+        };
+
+        scaled[idx] += 1;
+        remainders[idx] = 0;
+        extra -= 1;
+    }
+
+    if extra > 0 {
+        for idx in 0..components.len() {
+            if extra == 0 {
+                break;
+            }
+            if components[idx] == 0 {
+                continue;
+            }
+            if scaled[idx] as u16 >= components[idx] as u16 {
+                continue;
+            }
+
+            scaled[idx] += 1;
+            extra -= 1;
+        }
+    }
+
     RGB8 {
-        r: (u16::from(color.r) * u16::from(factor) / 255) as u8,
-        g: (u16::from(color.g) * u16::from(factor) / 255) as u8,
-        b: (u16::from(color.b) * u16::from(factor) / 255) as u8,
+        r: scaled[0],
+        g: scaled[1],
+        b: scaled[2],
+    }
+}
+
+#[cfg(all(test, feature = "std"))]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn breathing_pause_turns_led_off() {
+        // The breathing pause should hold the LED dark between cycles.
+        let pause = breathe(COLOR_GREEN, BREATH_PERIOD_MS + BREATH_PAUSE_MS / 2, BREATH_PERIOD_MS);
+        assert_eq!(pause, COLOR_OFF);
+
+        let restart = breathe(
+            COLOR_GREEN,
+            BREATH_PERIOD_MS + BREATH_PAUSE_MS + BREATH_PERIOD_MS / 4,
+            BREATH_PERIOD_MS,
+        );
+        assert!(restart.g > 0);
+    }
+
+    #[test]
+    fn breathing_waveform_is_symmetric() {
+        // Breathing should ramp up from dark, peak at the midpoint, and return to dark.
+        let start = breathe(COLOR_GREEN, 0, BREATH_PERIOD_MS);
+        let quarter = breathe(COLOR_GREEN, BREATH_PERIOD_MS / 4, BREATH_PERIOD_MS);
+        let half = breathe(COLOR_GREEN, BREATH_PERIOD_MS / 2, BREATH_PERIOD_MS);
+        let end = breathe(COLOR_GREEN, BREATH_PERIOD_MS, BREATH_PERIOD_MS);
+
+        assert_eq!(start.g, 0);
+        assert!(quarter.g > start.g);
+        assert_eq!(half, COLOR_GREEN);
+        assert_eq!(end.g, 0);
+    }
+
+    #[test]
+    fn scale_preserves_color_mix() {
+        // Scaling at low brightness must keep the same colour ratios.
+        let base = COLOR_ORANGE;
+        let dimmed = scale_color(base, 50);
+        assert!(dimmed.r > 0);
+        assert!(dimmed.g > 0);
+        assert_eq!(dimmed.b, 0);
+        assert!(dimmed.r <= base.r);
+        assert!(dimmed.g <= base.g);
+        assert_eq!(
+            dimmed.r as u16 * base.g as u16,
+            dimmed.g as u16 * base.r as u16
+        );
+    }
+
+    #[test]
+    fn zero_factor_switches_off() {
+        // A zero factor should always blank the LED regardless of colour.
+        let off = scale_color(COLOR_BLUE, 0);
+        assert_eq!(off, COLOR_OFF);
+    }
+
+    #[test]
+    fn idle_mode_backdates_start_time() {
+        // Idle mode should start mid-breath so the LED resumes smoothly.
+        let now = 10_000;
+        let expected = now.saturating_sub(BREATH_PERIOD_MS / 2);
+        assert_eq!(mode_start_time(StatusMode::Idle, now), expected);
+        assert_eq!(mode_start_time(StatusMode::Active, now), now);
     }
 }