From 7ca6104e802044b8297db6eb326b882fa77dcae9 Mon Sep 17 00:00:00 2001
From: Thomas Kolb <thomas@tkolb.de>
Date: Fri, 18 Jun 2021 20:25:53 +0200
Subject: [PATCH] charge_control: refactoring, bug fixes

- Moved shared state transition checks to separate function
- Improved behaviour when the battery is full
---
 src/charge_control.c | 89 +++++++++++++++++++++++++++++---------------
 src/config.h         |  8 +++-
 2 files changed, 65 insertions(+), 32 deletions(-)

diff --git a/src/charge_control.c b/src/charge_control.c
index 02473d8..516223a 100644
--- a/src/charge_control.c
+++ b/src/charge_control.c
@@ -57,13 +57,46 @@ static fxp_t sleep_solar_current;
 static fxp_t sleep_solar_excess_voltage;
 
 
-static void control_solar_switch(fxp_t u_bat, fxp_t corridor_high, fxp_t corridor_low)
+static enum ChargeState control_solar_charging(
+		fxp_t corridor_high,
+		fxp_t corridor_low,
+		uint64_t uptime_ms,
+		struct MeasurementResult *meas,
+		enum ChargeState current_state,
+		uint64_t time_in_state)
 {
-	if(u_bat >= corridor_high) {
+	static uint64_t last_switch_change_time = 0;
+	uint64_t solar_switch_onoff_duration = uptime_ms - last_switch_change_time;
+
+	bool last_switch_state = power_switch_solar_status();
+
+	if(meas->u_bat >= corridor_high) {
 		power_switch_solar_off();
-	} else if(u_bat <= corridor_low) {
+	} else if(meas->u_bat <= corridor_low) {
 		power_switch_solar_on();
 	}
+
+	bool current_switch_state = power_switch_solar_status();
+
+	if(last_switch_state != current_switch_state) { // switch changed
+		last_switch_change_time = uptime_ms;
+		solar_switch_onoff_duration = 0;
+	}
+
+	// temperature limit
+	if(meas->temperature > internal_temperature_limit) {
+		return CHARGE_HIGH_TEMPERATURE;
+	}
+
+	// low-current limit (go to sleep at night)
+	if((time_in_state > SLEEP_STATE_DELAY)
+			&& (current_switch_state == true)
+			&& (solar_switch_onoff_duration > SLEEP_SWITCH_DELAY)
+			&& (meas->i_solar < sleep_solar_current)) {
+		return CHARGE_SLEEP;
+	}
+
+	return current_state;
 }
 
 
@@ -86,52 +119,46 @@ static void solar_fsm_update(uint64_t uptime_ms, struct MeasurementResult *meas)
 			break;
 
 		case CHARGE_INITIAL:
-			control_solar_switch(meas->u_bat, u_bat_initial_full, u_bat_initial_low);
-
-			// temperature limit
-			if(meas->temperature > internal_temperature_limit) {
-				charge_state = CHARGE_HIGH_TEMPERATURE;
-				break;
-			}
+			charge_state = control_solar_charging(
+					u_bat_initial_full,
+					u_bat_initial_low,
+					uptime_ms,
+					meas,
+					charge_state,
+					charge_time_in_state);
 
 			// time limit for initial charging
 			if(charge_time_in_state > INITIAL_CHARGE_HOLD_TIME) {
 				charge_state = CHARGE_TRANSITION;
-				break;
 			}
 
-			// low-current limit (go to sleep at night)
-			if(meas->i_solar < sleep_solar_current) {
-				charge_state = CHARGE_SLEEP;
-				break;
-			}
 			break;
 
 		case CHARGE_TRANSITION:
 			// FIXME: dynamically adjust thresholds
-			control_solar_switch(meas->u_bat, u_bat_float_full, u_bat_float_low);
-
-			// temperature limit
-			if(meas->temperature > internal_temperature_limit) {
-				charge_state = CHARGE_HIGH_TEMPERATURE;
-				break;
-			}
+			charge_state = control_solar_charging(
+					u_bat_float_full,
+					u_bat_float_low,
+					uptime_ms,
+					meas,
+					charge_state,
+					charge_time_in_state);
 
 			// time limit for transition to float charging
 			if(charge_time_in_state > INITIAL_TO_FLOAT_TRANSITION_TIME) {
 				charge_state = CHARGE_FLOAT;
 				break;
 			}
-
-			// low-current limit (go to sleep at night)
-			if(meas->i_solar < sleep_solar_current) {
-				charge_state = CHARGE_SLEEP;
-				break;
-			}
 			break;
 
 		case CHARGE_FLOAT:
-			control_solar_switch(meas->u_bat, u_bat_float_full, u_bat_float_low);
+			charge_state = control_solar_charging(
+					u_bat_float_full,
+					u_bat_float_low,
+					uptime_ms,
+					meas,
+					charge_state,
+					charge_time_in_state);
 
 			// temperature limit
 			if(meas->temperature > internal_temperature_limit) {
@@ -195,7 +222,7 @@ static void load_fsm_update(uint64_t uptime_ms, struct MeasurementResult *meas)
 			// calculate charge pump output excess voltage over battery voltage
 			// and compare to the threshold
 			if(fxp_sub(meas->u_sw, meas->u_bat) > min_charge_pump_excess_voltage) {
-				discharge_state = DISCHARGE_VOLTAGE_LOW;
+				discharge_state = DISCHARGE_OK;
 			}
 			break;
 
diff --git a/src/config.h b/src/config.h
index 3a1f477..8ac166b 100644
--- a/src/config.h
+++ b/src/config.h
@@ -24,7 +24,13 @@
 
 /* Minimum charge current required before charging is stopped to save power at
  * the charge pump (in mA). */
-#define SLEEP_SOLAR_CURRENT    5
+#define SLEEP_SOLAR_CURRENT    1
+
+/* Delay between state change and sleep state check (in ms). */
+#define SLEEP_STATE_DELAY      100
+
+/* Delay between charging switch state change and sleep state check(in ms). */
+#define SLEEP_SWITCH_DELAY    1000
 
 /* Maximum allowed microcontroller temperature (in units of 0.1 °C). If this
  * temperature is exceeded, charging is stopped. The load is kept on. Do not