[battery,bus] stay in cold out hibernate when the bus voltage is less than 2.5V

firmware/inc/hw_config/low-power-solar.h

@@ -148,7 +148,15 @@
  */
 #define RECHARGABLE_BATTERY	1
 #define CHG_ENABLE_PIN		PIN_PA27
-#define RECHARGABLE_MIN_V	(2.6)
+#define RECHARGABLE_MIN_V	(2.7)
+
+/**
+ * Power Bus
+ * bus is currently called solar
+ */
+/* bus is low when <2.5V, which corresponds to ~2.7V battery voltage */
+/* usually evaluated with minimal load on the battery  */
+#define IS_BUS_LOW(dp)		(get_solar() < 2.5)
 
 /**
  * Cold out

firmware/src/main.c

@@ -343,7 +343,11 @@ int main(void)
       start_adc_sequence();
       while (is_adc_sequence_done() == 0); /* wait for adc */
 
-
+#ifdef IS_BUS_LOW
+      if (IS_BUS_LOW()) {
+        set_cycle_time(1);      /* set cycle time for cold out */
+      } else {
+#endif
         if (in_cold_out == 1) {
           external_temperature = thermistor_ratio_to_temperature(get_thermistor()); /* read */
           if ((external_temperature < COLD_OUT_TEMPERATURE) && /* check temperature */
@@ -359,9 +363,11 @@ int main(void)
           run_sequencer(n++, cycle_time_s);   /* run */
         }
 
-      /* Hibernate timing */
+        set_cycle_time(in_cold_out); /* set cycle time as required */
-      set_cycle_time(in_cold_out);
 
+#ifdef IS_BUS_LOW
+      }
+#endif
 
 
       system_set_sleepmode(SYSTEM_SLEEPMODE_STANDBY); /* Lowest power */