add runtime threshold for battery low

Author: sctanf

Kconfig

@@ -34,6 +34,13 @@ config BATTERY_NO_MAPPING
 
 endchoice
 
+config BATTERY_LOW_RUNTIME_THRESHOLD
+    int "Low battery runtime threshold (ms)"
+    default 10800000
+    help
+      Trigger low battery when estimated runtime falls below threshold.
+      If estimated runtime is not available, low battery will trigger under 10% estimated state of charge.
+
 choice
 	prompt "Status LED color mapping"
     default LED_TRI_COLOR
@@ -168,7 +175,7 @@ config USE_ACTIVE_TIMEOUT
     help
         Delay IMU wake up state or user shutdown during activity.
 
-choice 
+choice
     prompt "Activity timeout mode"
     default SLEEP_ON_ACTIVE_TIMEOUT
     depends on USE_ACTIVE_TIMEOUT

src/config.c

@@ -49,6 +49,7 @@ const char *config_settings_names[] = {
 	"imu_timeout_ramp_max",
 	"active_timeout_threshold",
 	"active_timeout_delay",
+	"battery_low_runtime_threshold"
 };
 
 const bool config_0_settings_defaults[16] = {
@@ -133,6 +134,7 @@ const int32_t config_3_settings_defaults[16] = {
 #else
 	900000,
 #endif
+	CONFIG_BATTERY_LOW_RUNTIME_THRESHOLD,
 };
 
 LOG_MODULE_REGISTER(config, LOG_LEVEL_INF);

src/config.h

@@ -63,6 +63,7 @@ enum config_3_settings_id {
 	CONFIG_3_IMU_TIMEOUT_RAMP_MAX,
 	CONFIG_3_ACTIVE_TIMEOUT_THRESHOLD,
 	CONFIG_3_ACTIVE_TIMEOUT_DELAY,
+	CONFIG_3_BATTERY_LOW_RUNTIME_THRESHOLD,
 	CONFIG_3_SETTINGS_END
 };
 

src/system/power.c

@@ -521,9 +521,14 @@ static void power_thread(void)
 		// will update average_pptt, and current_battery_pptt
 		update_battery(battery_pptt);
 
-		if (battery_available && !battery_low && current_battery_pptt < 1000)
+		// use estimated remaining runtime or pptt for battery_low
+		uint64_t runtime = sys_get_battery_remaining_time_estimate();
+		bool runtime_valid = runtime;
+		bool runtime_low = k_ticks_to_us_floor64(runtime) < CONFIG_3_SETTINGS_READ(CONFIG_3_BATTERY_LOW_RUNTIME_THRESHOLD);
+		bool pptt_low = current_battery_pptt < 1000;
+		if (battery_available && !battery_low && (runtime_valid ? runtime_low : pptt_low))
 			battery_low = true;
-		else if (!battery_available || (battery_low && current_battery_pptt > 1000)) // hysteresis alrerady provided
+		else if (!battery_available || (battery_low && (runtime_valid ? !runtime_low : !pptt_low))) // hysteresis already provided
 			battery_low = false;
 
 		sys_update_battery_tracker_voltage(battery_mV, device_plugged);