Fix PM5 auto-off leaving the board unable to power back on

CHANGELOG.md

@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+- Fixed `PM5 auto-off` - no longer powers the board into a state it can't be woken from (@nemanjan00)
 - Fixed `tools/ePassport` - FILES and LOG panes no longer go blank on long content, and picture files now show the picture (@pkilar)
 - Fixed `hf xerox view` - now rejects a dump file too small to contain the info blocks instead of reading past it (@munzzyy)
 - Changed NG frame layout to align better with 64bytes frames. From 512 -> 624bytes (@iceman1001)

armsrc/appmain.c

@@ -110,9 +110,20 @@ static bool s_autooff_setup = false;
 // unplugged at all (and the hw bwmautooff toggle would be unreachable, since setting it
 // needs a client/USB). So we require having seen USB present at least once this session
 // before an absent reading triggers shutdown.
+#ifndef PM5_AUTOOFF_CONFIRMATIONS
+// Consecutive absent samples required before powering off (x PM5_AUTOOFF_POLL_MS).
+// This is the grace period the comment above has always promised, and it is not only
+// glitch rejection: pulling VBUS puts the BWM charger into Battery Discharge Mode, and
+// BATFET is only turned fully on as part of that transition. Releasing the power latch
+// 250ms in leaves the charger mid-transition and the board will not power on again -
+// waiting lets DISCHG settle first.
+#define PM5_AUTOOFF_CONFIRMATIONS  20      // 20 x 250ms = 5s
+#endif
+
 static void bwm_autooff_check(void) {
     static uint32_t last_tick = 0;
     static bool usb_was_present = false;   // have we seen USB present since boot?
+    static uint8_t absent = 0;             // consecutive USB-absent samples
 
     if (g_autooff_enabled == false) {
         return;
@@ -130,6 +141,7 @@ static void bwm_autooff_check(void) {
     // Gpio_VUSB_Read() == true means USB power present.
     if (Gpio_VUSB_Read()) {
         usb_was_present = true;   // latch: USB has been present this session
+        absent = 0;               // present again -> restart the grace period
         return;
     }
 
@@ -139,6 +151,11 @@ static void bwm_autooff_check(void) {
         return;
     }
 
+    // Require the absence to persist before acting on it.
+    if (++absent < PM5_AUTOOFF_CONFIRMATIONS) {
+        return;
+    }
+
     LEDsoff();
     Gpio_ARM_Power_ON_Low();
     while (1); // wait for hardware power-off (button press powers back on, in hardware)