Pip: real deep sleep after 3 min idle, woken by power button

Replaces the old light-sleep-with-1.5s-timer-poll approach with proper
ESP32 deep sleep, which drops standby current from ~1 mA to ~10–150 µA.

Idle ramp on Pip is now:
  30 s  → display dims to BRIGHT_DIM
  60 s  → BRIGHT_DARK + Sleeping UI (unchanged)
  3 min → M5.Power.deepSleep(0, true) — wakes only on the power button
          (GPIO35 on M5StickC Plus 2)

Force-sleep (BtnB / BtnA-hold) gets a FORCE_SLEEP_GRACE_MS = 3 s window
during which BtnA still cancels the sleep, then drops into deep sleep
the same way. NVS is saved and the speaker is torn down before the
deepSleep() call so the buzzer doesn't pop on the way down.

Drops LIGHT_SLEEP_MS and DISPLAY_OFF_AFTER_MS from pip_tuning.h.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Marcel Dütscher

src/main_pip.cpp

@@ -10,11 +10,16 @@
 // State machine:
 //   Idle      → display shows treat + hint, ready for input
 //   Throwing  → ~800 ms post-shake animation (treat flies up + fades)
-//   Sleeping  → 30 s idle → Zzz screen (auto-dims separately)
+//   Sleeping  → 60 s idle → Zzz screen
+//
+// Power ramp:
+//   30 s → display dims to BRIGHT_DIM
+//   60 s → BRIGHT_DARK + Sleeping UI
+//   3 min → ESP32 deep sleep, woken by the power button (GPIO35)
 //
 // Inputs:
 //   BtnA  — cycle Apple → Carrot → Bone → Apple
-//   BtnB  — force sleep
+//   BtnB  — force sleep (3 s grace, then deep sleep)
 //   shake — throw the currently selected treat
 //
 // Compiled only in [env:pip] / [env:pip-s3].
@@ -23,7 +28,6 @@
 #include <M5Unified.h>
 #include <Preferences.h>
 #include <math.h>
-#include <esp_sleep.h>
 #include <esp32-hal-cpu.h>
 
 #include "target_caps.h"
@@ -42,6 +46,10 @@ struct PipState {
     pip::UiState   state              = pip::UiState::Idle;
     pip::MenuPage  page               = pip::MenuPage::Empty;
     bool           forceSleep         = false;
+    // Set when forceSleep flips from false to true. Used to gate the
+    // grace period before we actually drop into deep sleep, so an
+    // accidental BtnB press can be cancelled with a BtnA click.
+    uint32_t       forceSleepStartMs  = 0;
     uint32_t       lastInteractionMs  = 0;
     uint32_t       throwStartMs       = 0;
     uint32_t       lastSavedMs        = 0;
@@ -224,22 +232,27 @@ void updateUiState(uint32_t now) {
 // the threshold is crossed during the press.
 void handleButtons(uint32_t now) {
     if (M5.BtnA.wasHold()) {
-        g_pet.forceSleep = true;
+        g_pet.forceSleep        = true;
+        g_pet.forceSleepStartMs = now;
         pip::play(pip::Sound::Sleepy);
         return;
     }
     if (M5.BtnA.wasClicked()) {
         if (g_pet.forceSleep) {
-            // Wake from forced sleep instead of cycling pages.
-            g_pet.forceSleep = false;
+            // Wake from forced sleep instead of cycling pages — only
+            // works while we're still inside the grace window before
+            // deep sleep kicks in.
+            g_pet.forceSleep        = false;
+            g_pet.forceSleepStartMs = 0;
             g_pet.lastInteractionMs = now;
             pip::play(pip::Sound::Wake);
             return;
         }
         cyclePage(now);
     }
     if (M5.BtnB.wasClicked()) {
-        g_pet.forceSleep = true;
+        g_pet.forceSleep        = true;
+        g_pet.forceSleepStartMs = now;
         pip::play(pip::Sound::Sleepy);
     }
 }
@@ -272,30 +285,44 @@ void saveState() {
 }
 
 // ── Display power (mobile strategy) ────────────────────────────────────────
+//
+// Two-step idle ramp:
+//   30 s → BRIGHT_DIM
+//   60 s → BRIGHT_DARK + Sleeping UI (set by updateUiState)
+//   3 min → ESP32 deep sleep, woken by the power button
+//
+// Force-sleep (BtnB / BtnA-hold) skips the ramp: it shows the Zzz UI for
+// FORCE_SLEEP_GRACE_MS so an accidental press can be undone with BtnA,
+// then drops into deep sleep too.
 uint8_t g_brightness = pip::BRIGHT_NORMAL;
 uint8_t g_curBrightness = 0xFF;
-bool    g_displayAsleep = false;
+
+void enterDeepSleep() {
+    Serial.println(F("[pip] entering deep sleep"));
+    saveState();
+    M5.Speaker.end();
+    // M5.Power.deepSleep(0, true) handles M5.Display.sleep(), enables
+    // ext0/ext1 wakeup on the board's _wakeupPin (GPIO35 = power button
+    // on StickC Plus 2), then calls esp_deep_sleep_start(). 0 = no timer
+    // wakeup; the device only comes back via the power button.
+    M5.Power.deepSleep(0, true);
+}
 
 void applyDisplayPower(uint32_t now) {
     uint32_t idle = now - g_pet.lastInteractionMs;
-    uint8_t  target;
-    bool     wantSleep = false;
-    if      (idle >= pip::DISPLAY_OFF_AFTER_MS) { target = 0;                 wantSleep = true; }
-    else if (idle >= pip::DARK_AFTER_MS)        { target = pip::BRIGHT_DARK;  }
-    else if (idle >= pip::DIM_AFTER_MS)         { target = pip::BRIGHT_DIM;   }
-    else                                         { target = g_brightness;     }
-
-    if (wantSleep && !g_displayAsleep) {
-        M5.Display.setBrightness(0);
-        M5.Display.sleep();
-        g_displayAsleep = true;
-        g_curBrightness = 0;
-        return;
-    }
-    if (!wantSleep && g_displayAsleep) {
-        M5.Display.wakeup();
-        g_displayAsleep = false;
+
+    bool forceSleepRipe = g_pet.forceSleep
+        && (now - g_pet.forceSleepStartMs) >= pip::FORCE_SLEEP_GRACE_MS;
+    if (idle >= pip::DEEP_SLEEP_AFTER_MS || forceSleepRipe) {
+        enterDeepSleep();
+        // unreachable
     }
+
+    uint8_t target;
+    if      (idle >= pip::DARK_AFTER_MS) target = pip::BRIGHT_DARK;
+    else if (idle >= pip::DIM_AFTER_MS)  target = pip::BRIGHT_DIM;
+    else                                 target = g_brightness;
+
     if (target != g_curBrightness) {
         M5.Display.setBrightness(target);
         g_curBrightness = target;
@@ -500,20 +527,8 @@ void loop() {
         saveState();
     }
 
-    // Display power (auto-dim).
+    // Display power (auto-dim, then deep sleep).
     applyDisplayPower(now);
-    if (g_displayAsleep) {
-        // Tear down the speaker before light-sleep: the buzzer's LEDC
-        // channel pops audibly when it stops/restarts at sleep entry/exit
-        // every ~1.5 s, which manifests as a slow "click click" while Pip
-        // is supposed to be silent. Re-init on wake; the cost is well
-        // under the per-cycle wake overhead and silence wins.
-        M5.Speaker.end();
-        esp_sleep_enable_timer_wakeup((uint64_t)pip::LIGHT_SLEEP_MS * 1000ULL);
-        esp_light_sleep_start();
-        M5.Speaker.begin();
-        return;
-    }
 
     // Render.
     pip::PipView v{};

src/pip/pip_tuning.h

@@ -38,14 +38,16 @@ constexpr uint32_t BTN_HOLD_SLEEP_MS     = 600;
 // Mobile power strategy.
 constexpr uint32_t DIM_AFTER_MS          = 30000;   // 30 s → half brightness
 constexpr uint32_t DARK_AFTER_MS         = 60000;   // 60 s → 5 % brightness
-constexpr uint32_t DISPLAY_OFF_AFTER_MS  = 300000;  // 5 min → display off
+constexpr uint32_t DEEP_SLEEP_AFTER_MS   = 180000;  // 3 min → ESP32 deep sleep
 constexpr uint8_t  BRIGHT_NORMAL         = 150;
 constexpr uint8_t  BRIGHT_DIM            =  60;
 constexpr uint8_t  BRIGHT_DARK           =  12;
 
-// Light-sleep period while the display is off. Wake every X ms for an
-// IMU check ("pet taken out of pocket" → display back on).
-constexpr uint32_t LIGHT_SLEEP_MS        = 1500;
+// Grace period after a force-sleep button press before we actually enter
+// deep sleep. Long enough that the user can cancel via BtnA if they hit
+// BtnB by accident, short enough that "I want to save power now" still
+// feels responsive.
+constexpr uint32_t FORCE_SLEEP_GRACE_MS  = 3000;
 
 // Battery threshold at boot. Below this percent we don't go into full
 // operation — show "Low Battery" briefly and deep-sleep, otherwise the