From 9f2fd682e52d5c434c57563afdcb0be91bc0b2f0 Mon Sep 17 00:00:00 2001
From: Msprg <18015488+Msprg@users.noreply.github.com>
Date: Wed, 2 Sep 2026 11:33:32 +0200
Subject: [PATCH] PM5 low-batt shutdown: gate power-off on VUSB pin, not
 charger PG bit

The critical-shutdown path in bwm_lowbatt_check() was reached whenever the
AW32001 System Status "power good" bit was clear. On this hardware that bit reads
"power fail" even while the board is USB-powered under HF load (hw status shows
power fail + ~400 mA discharge on PC USB), so a low pack could trip the latched
power-off - Gpio_ARM_Power_ON_Low() + while(1) - while USB keeps the MCU alive,
leaving it spinning.

Confirm the cable really is out via the dedicated VUSB sense pin (Gpio_VUSB_Read,
the same source WITH_PM5_AUTOOFF uses) before powering off; if USB is present,
clear the streak and keep running. Also print a reason before cut-off, and fix a
brace/formatting glitch on the trigger condition.
---
 armsrc/bwm_charger.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/armsrc/bwm_charger.c b/armsrc/bwm_charger.c
index 160f04e23..7f51438a3 100644
--- a/armsrc/bwm_charger.c
+++ b/armsrc/bwm_charger.c
@@ -471,6 +471,7 @@ void bwm_lowbatt_check(void) {
     static uint32_t last_tick = 0;
 #ifdef WITH_PM5_LOWBATT_SHUTDOWN
     static uint8_t crit = 0;
+    static bool s_vusb_setup = false;
 #endif
 
     if ((last_tick != 0) && (GetTickCountDelta(last_tick) < BWM_LOWBATT_PERIOD_MS)) {
@@ -503,11 +504,23 @@ void bwm_lowbatt_check(void) {
     // uncalibrated gauge - e.g. <3% reported at 3.6 V). Never let SoC alone
     // trigger power-off: require the pack to also be in the low-batt zone.
     if ((mv <= BWM_SHUTDOWN_MV) ||
-            ((soc <= BWM_SHUTDOWN_SOC_PCT) && (mv <= BWM_LOWBATT_MV))) {        if (++crit >= BWM_SHUTDOWN_CONFIRMATIONS) {
-            bwm_beep_low_batt();   // final audible warning before cut-off
-            LEDsoff();
-            Gpio_ARM_Power_ON_Low();
-            while (1);             // wait for hardware power-off
+            ((soc <= BWM_SHUTDOWN_SOC_PCT) && (mv <= BWM_LOWBATT_MV))) {
+        if (++crit >= BWM_SHUTDOWN_CONFIRMATIONS) {
+            // Confirm on the VUSB pin, not the charger PG bit: PG can read
+            // "power fail" on USB under load, so only power off if USB is really out.
+            if (s_vusb_setup == false) {
+                gpio_vusb_setup();
+                s_vusb_setup = true;
+            }
+            if (Gpio_VUSB_Read()) {
+                crit = 0;          // USB present, not a real drain
+            } else {
+                Dbprintf(_RED_("[BWM] critical battery %u mV / %u%% - powering off"), mv, soc);
+                bwm_beep_low_batt();   // last warning before cut-off
+                LEDsoff();
+                Gpio_ARM_Power_ON_Low();
+                while (1);             // wait for power-off
+            }
         }
     } else {
         crit = 0;                  // recovered above the floor -> reset the streak