From f909f26ea79944265a294c0ffc280924d8615ed4 Mon Sep 17 00:00:00 2001
From: Thomas Kolb <thomas@tkolb.de>
Date: Sat, 3 Sep 2016 16:57:33 +0200
Subject: [PATCH] Implemented load management

---
 src/main.c | 48 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 45 insertions(+), 3 deletions(-)

diff --git a/src/main.c b/src/main.c
index ab60937..149488a 100644
--- a/src/main.c
+++ b/src/main.c
@@ -24,6 +24,7 @@
 #define TIM_CH_BOOTSTRAP TIM_OC2
 
 #define MAX_SLEEP_TIME 3600
+#define MAX_SLEEP_TIME_LOW_VOLTAGE 300
 
 enum OperState {
 	Bootstrap,
@@ -67,7 +68,6 @@ static void init_gpio(void)
 
 	// GPIO for load activation
 	gpio_mode_setup(GPIOA, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO15);
-	gpio_set(GPIOA, GPIO15);
 }
 
 static void init_clock(void)
@@ -493,6 +493,16 @@ static void mpp_run(
 	}
 }
 
+static void load_on(void)
+{
+	gpio_set(GPIOA, GPIO15);
+}
+
+static void load_off(void)
+{
+	gpio_clear(GPIOA, GPIO15);
+}
+
 int main(void)
 {
 	uint32_t cpuload = 0;
@@ -501,6 +511,7 @@ int main(void)
 	char msg[128];
 	char number[FXP_STR_MAXLEN];
 	uint8_t sentSomething = 0;
+	uint8_t loadInitialized = 0;
 
 	int32_t pwm = 0;
 
@@ -539,6 +550,15 @@ int main(void)
 	// input voltage must exceed output voltage by this value to leave idle mode
 	fxp_t WAKEUP_OFFSET_VOLTAGE = fxp_from_float(1.0f);
 
+	// switch off load below LOAD_OFF_THRESHOLD to protect the battery; when the
+	// battery recovers above LOAD_ON_THRESHOLD the load is switched on again.
+	//
+	// If the battery voltage is below LOAD_LOW_VOLTAGE_THRESHOLD, the battery
+	// voltage is monitored more closely during idle mode.
+	fxp_t LOAD_ON_THRESHOLD = fxp_from_float(13.000f);
+	fxp_t LOAD_OFF_THRESHOLD = fxp_from_float(11.200f);
+	fxp_t LOAD_LOW_VOLTAGE_THRESHOLD = fxp_from_float(11.600f);
+
 	// Calculated values
 	//fxp_t VIN_SCALE = fxp_from_float(3.3f * (100 + 12.4f) / 12.4f / 4095.0f);
 	//fxp_t VOUT_SCALE = fxp_from_float(3.3f * (100 + 12.0f) / 12.0f / 4095.0f);
@@ -639,6 +659,22 @@ int main(void)
 
 		power_state.power_avg = fxp_mult(power_state.vout_avg, power_state.current_avg);
 
+		// load management
+		if(timebase_ms >= 100) {
+			if(!loadInitialized && power_state.vout_avg > LOAD_OFF_THRESHOLD) {
+				load_on();
+				loadInitialized = 1;
+			}
+
+			if(loadInitialized) {
+				if(power_state.vout_avg < LOAD_OFF_THRESHOLD) {
+					load_off();
+				} else if(power_state.vout_avg > LOAD_ON_THRESHOLD) {
+					load_on();
+				} /* else current state is kept */
+			}
+		}
+
 		// Main FSM
 		if(timebase_ms >= 1000) {
 			switch(operState) {
@@ -832,8 +868,14 @@ int main(void)
 						time_in_state = 9900; // run the voltage test again
 
 						sleep_time *= 2;
-						if(sleep_time > MAX_SLEEP_TIME) {
-							sleep_time = MAX_SLEEP_TIME;
+						if(power_state.vout_avg > LOAD_LOW_VOLTAGE_THRESHOLD) {
+							if(sleep_time > MAX_SLEEP_TIME) {
+								sleep_time = MAX_SLEEP_TIME;
+							}
+						} else {
+							if(sleep_time > MAX_SLEEP_TIME_LOW_VOLTAGE) {
+								sleep_time = MAX_SLEEP_TIME_LOW_VOLTAGE;
+							}
 						}
 
 						force_display_update_time = timebase_ms + 10;