Fix/battery voltage

lib/EFBoard/EFBoard.cpp

@@ -33,7 +33,6 @@
 
 #include "EFBoard.h"
 
-
 RTC_DATA_ATTR uint32_t bootCount = 0;
 
 volatile int8_t ota_last_progress = -1;
@@ -74,6 +73,7 @@ void EFBoardClass::setup() {
     randomSeed(analogRead(0));
 
     // Check power state
+    this->updatePowerState();
     const EFBoardPowerState pwrstate = this->getPowerState();
     if (pwrstate == EFBoardPowerState::BAT_BROWN_OUT_HARD) {
         LOGF_ERROR("(EFBoard) HARD BROWN OUT DETECTED (V_BAT = %.2f V). Panic!\r\n", this->getBatteryVoltage());
@@ -138,8 +138,15 @@ const char *EFBoardClass::getWakeupReason() {
 }
 
 const float EFBoardClass::getBatteryVoltage() {
-    // voltageBattery = adcValue * voltPerADCStep * voltageDividerRatio
-    return (analogRead(EFBOARD_PIN_VBAT) * (3.3 / 4095.0)) * ((51.1 + 100.0) / 100.0);
+    // Voltage divider resistors: R11 = 51.1k, R12 = 100k
+    constexpr float R1 = 51.1f;
+    constexpr float R2 = 100.0f;
+    constexpr float ADC_MAX_VALUE = 4095.0f;
+    constexpr float ADC_REF_VOLTAGE = 3.5f; // Reference voltage for ADC. Should be 3.3V, but the results are wonky. 3.5 works better
+
+    constexpr float voltage_divider_factor = (R1 + R2) / R2;
+    float battery_voltage = (analogRead(EFBOARD_PIN_VBAT) * (ADC_REF_VOLTAGE / ADC_MAX_VALUE)) * voltage_divider_factor;
+    return battery_voltage;
 }
 
 const bool EFBoardClass::isBatteryPowered() {
@@ -149,7 +156,7 @@ const bool EFBoardClass::isBatteryPowered() {
 const uint8_t EFBoardClass::getBatteryCapacityPercent() {
     /* Used Varta Longlife AA cells discharge curve as a base.
      *
-     * We consider 1.16 V as empty even though the cells are not empty at that
+     * We consider 1.12 V as empty even though the cells are not empty at that
      * point due to the brown out voltage of the DC/DC for the 3.3V rail.
      *
      * Data points used to fit cubic function to:
@@ -160,6 +167,7 @@ const uint8_t EFBoardClass::getBatteryCapacityPercent() {
      *   - 1.20 V =  23 %
      *   - 1.16 V =   0 %
      */
+    // TODO: This is a bit outdated/off
     double vBatCell = this->getBatteryVoltage() / 3.0;
     double percent = (14.9679 * pow(vBatCell, 3) - 68.9823 * pow(vBatCell, 2) + 106.4289 * vBatCell - 54.0063) * 100.0;
     return max(min((int) round(percent), 100), 0);
@@ -169,7 +177,21 @@ const EFBoardPowerState EFBoardClass::updatePowerState() {
     if (!this->isBatteryPowered()) {
         this->power_state = EFBoardPowerState::USB;
     } else {
-        const float vbat = this->getBatteryVoltage();
+        float vbat = this->getBatteryVoltage();
+
+        if (vbat <= EFBOARD_BROWN_OUT_SOFT) {
+            // A low-battery state could be a momentary spike
+            // We take multiple samples to make sure we are really low on battery
+            float sum = 0.0f;
+            constexpr uint8_t samples = 5;
+            for (uint8_t i = 0; i < samples; i++) {
+                sum += this->getBatteryVoltage();
+                delay(1);
+            }
+            vbat = sum / samples;
+            LOGF("BATTERY: Measurement average: %f\r\n", vbat);
+        }
+
         if (vbat <= EFBOARD_BROWN_OUT_HARD || this->power_state == EFBoardPowerState::BAT_BROWN_OUT_HARD) {
             this->power_state = EFBoardPowerState::BAT_BROWN_OUT_HARD;
         } else if (vbat <= EFBOARD_BROWN_OUT_SOFT || this->power_state == EFBoardPowerState::BAT_BROWN_OUT_SOFT) {

lib/EFBoard/EFBoard.h

@@ -34,13 +34,13 @@
 #define EFBOARD_SERIAL_BAUD 115200         //!< Baudrate for the serial device
 
 // The Step-Down converter still manages to hold 3.00V with 3,32V input. The ESP needs 3.0V at least
-#define EFBOARD_PIN_VBAT 10                //!< Pin the analog voltage divider for V_BAT is connected to
+#define EFBOARD_PIN_VBAT 10                //!< Pin the analog voltage divider for V_BAT is connected to (ADC1_CH9)
 #define EFBOARD_NUM_BATTERIES 3            //!< Number of battery cells used for V_BAT
 #define EFBOARD_VBAT_MAX (1.60 * EFBOARD_NUM_BATTERIES) //!< Voltage at which battery cells are considered full
-#define EFBOARD_VBAT_MIN (1.12 * EFBOARD_NUM_BATTERIES) //!< Voltage at which battery cells are considered empty
+#define EFBOARD_VBAT_MIN (1.13 * EFBOARD_NUM_BATTERIES) //!< Voltage at which battery cells are considered empty
 
 #define EFBOARD_BROWN_OUT_SOFT EFBOARD_VBAT_MIN //!< V_BAT threshold after which a soft brown out is triggered
-#define EFBOARD_BROWN_OUT_HARD 3.30             //!< V_BAT threshold after which a hard brown out is triggered
+#define EFBOARD_BROWN_OUT_HARD (EFBOARD_BROWN_OUT_SOFT - 0.08) //!< V_BAT threshold after which a hard brown out is triggered
 
 
 /**

src/main.cpp

@@ -39,7 +39,7 @@
 #include "util.h"
 
 // Global objects and states
-constexpr unsigned int INTERVAL_BATTERY_CHECK = 60000;
+constexpr unsigned int INTERVAL_BATTERY_CHECK = 10000;
 // Initializing the board with a brightness above 48 can cause stability issues!
 constexpr uint8_t ABSOLUTE_MAX_BRIGHTNESS = 45;
 FSM fsm(10);
@@ -90,7 +90,7 @@ void _hardBrownOutHandler() {
     );
     EFBoard.disableWifi();
     // Try getting the LEDs into some known state
-    EFLed.setBrightnessPercent(20);
+    EFLed.setBrightnessPercent(30);
     EFLed.clear();
     EFLed.setDragonNose(CRGB::Red);
 
@@ -99,10 +99,10 @@ void _hardBrownOutHandler() {
         // Low brightness blink every few seconds
         EFLed.enablePower();
         EFLed.setDragonNose(CRGB::Red);
-        esp_sleep_enable_timer_wakeup(80 * 1000);  // in ms
+        esp_sleep_enable_timer_wakeup(200 * 1000);  // 200 ms
         EFLed.disablePower();
         // sleep most of the time.
-        esp_sleep_enable_timer_wakeup(4 * 1000000);
+        esp_sleep_enable_timer_wakeup(2 * 1000 * 1000);  // 2s
         esp_light_sleep_start();
         // TODO: Go to deep sleep, but save the reason so when waking up, we can blink and deep sleep again
     }
@@ -134,10 +134,10 @@ void _softBrownOutHandler() {
         for (uint8_t n = 0; n < 30; n++) {
             EFLed.enablePower();
             EFLed.setDragonNose(CRGB::Red);
-            esp_sleep_enable_timer_wakeup(200 * 1000);
+            esp_sleep_enable_timer_wakeup(300 * 1000);
             esp_light_sleep_start();
             EFLed.disablePower();
-            esp_sleep_enable_timer_wakeup(800 * 1000);
+            esp_sleep_enable_timer_wakeup(700 * 1000);
             esp_light_sleep_start();
         }
 
@@ -150,6 +150,30 @@ void _softBrownOutHandler() {
     }
 }
 
+void batteryCheck() {
+    EFBoardPowerState previousState = pwrstate;
+    pwrstate = EFBoard.updatePowerState();
+    if (previousState != pwrstate) {
+        LOGF_DEBUG("Updated power state: %s\r\n", toString(pwrstate));
+    }
+
+    // Log battery level if battery powered
+    if (EFBoard.isBatteryPowered()) {
+        LOGF_INFO(
+            "Battery voltage: %.2f V (%d %%)\r\n",
+            EFBoard.getBatteryVoltage(),
+            EFBoard.getBatteryCapacityPercent()
+        );
+    }
+
+    // Handle brown out
+    if (pwrstate == EFBoardPowerState::BAT_BROWN_OUT_HARD) {
+        _hardBrownOutHandler();
+    } else if (pwrstate == EFBoardPowerState::BAT_BROWN_OUT_SOFT) {
+        _softBrownOutHandler();
+    }
+}
+
 /**
  * @brief Calculates a wave animation. Used by bootupAnimation()
  */
@@ -164,7 +188,7 @@ float wave_function(float x, float start, float end, float amplitude) {
 /**
  * @brief Displays a fancy bootup animation
  */
-void bootupAnimation() {
+void boopupAnimation() {
     CRGB data[EFLED_TOTAL_NUM];
     fill_solid(data, EFLED_TOTAL_NUM, CRGB::Black);
     EFLed.setAll(data);
@@ -177,6 +201,10 @@ void bootupAnimation() {
 
     for (uint16_t n = 0; n < 30; n++) {
         uint16_t n_scaled = n * 7;
+        if (n % 10) {
+            // Low batteries might crash the boopup animation
+            batteryCheck();
+        }
         for (uint8_t i = 0; i < EFLED_TOTAL_NUM; i++) {
             int16_t dx = EFLedClass::getLEDPosition(i).x - pwrX;
             int16_t dy = EFLedClass::getLEDPosition(i).y - pwrY;
@@ -195,6 +223,7 @@ void bootupAnimation() {
     EFLed.clear();
     delay(400);
 
+    batteryCheck();
     // dragon awakens ;-)
     EFLed.setDragonEye(CRGB(10,0, 0));
     delay(60);
@@ -222,7 +251,7 @@ void setup() {
     EFBoard.setup();
     EFLed.init(ABSOLUTE_MAX_BRIGHTNESS);
     EFLed.setBrightnessPercent(40);  // We do not have access to the settings yet, default to 40
-    bootupAnimation();
+    boopupAnimation();
 
     // Touchy stuff
     EFTouch.init();
@@ -236,7 +265,7 @@ void setup() {
     EFTouch.attachInterruptOnLongpress(EFTouchZone::Nose, isr_noseLongpress);
     EFTouch.attachInterruptOnShortpress(EFTouchZone::All, isr_allShortpress);
     EFTouch.attachInterruptOnLongpress(EFTouchZone::All, isr_allLongpress);
-    
+
     // Get FSM going
     fsm.resume();
 }
@@ -313,25 +342,7 @@ void loop() {
 
     // Task: Battery checks
     if (task_battery < millis()) {
-        pwrstate = EFBoard.updatePowerState();
-        LOGF_DEBUG("Updated power state: %s\r\n", toString(pwrstate));
-
-        // Log battery level if battery powered
-        if (EFBoard.isBatteryPowered()) {
-            LOGF_INFO(
-                "Battery voltage: %.2f V (%d %%)\r\n",
-                EFBoard.getBatteryVoltage(),
-                EFBoard.getBatteryCapacityPercent()
-            );
-        }
-
-        // Handle brown out
-        if (pwrstate == EFBoardPowerState::BAT_BROWN_OUT_HARD) {
-            _hardBrownOutHandler();
-        } else if (pwrstate == EFBoardPowerState::BAT_BROWN_OUT_SOFT) {
-            _softBrownOutHandler();
-        }
-
+        batteryCheck();
         task_battery = millis() + INTERVAL_BATTERY_CHECK;
     }
 }