Load ratios after boot + show pwr defaults with `get` (#2241)

* emon: configure ratios without reboot

* settings: serialize() support

* debug: use vsnprintf from newlib, not from sdk

* settings/experimental: show defaults via `get`

* emon: override base methods, fix defaults

* sensor/emon: expose internal index calculation

- refactor configuration to use the correct index when accessing indexed
  sensor methods. store index value on magnitude, refactor loops to
  accomodate this new functionality
- rename slot(index) -> description(index), since we use 'slot' as
  numeric value

code/espurna/alexa.cpp

@@ -82,7 +82,7 @@ void _alexaBrokerCallback(const String& topic, unsigned char id, unsigned int va
 // -----------------------------------------------------------------------------
 
 bool alexaEnabled() {
-    return getSetting<bool>("alexaEnabled", 1 == ALEXA_ENABLED);
+    return getSetting("alexaEnabled", 1 == ALEXA_ENABLED);
 }
 
 void alexaLoop() {

code/espurna/button.cpp

@@ -42,6 +42,21 @@ debounce_event::types::Mode convert(const String& value) {
     }
 }
 
+template<>
+String serialize(const debounce_event::types::Mode& value) {
+    String result;
+    switch (value) {
+        case debounce_event::types::Mode::Switch:
+            result = "1";
+            break;
+        case debounce_event::types::Mode::Pushbutton:
+        default:
+            result = "0";
+            break;
+    }
+    return result;
+}
+
 template<>
 debounce_event::types::PinValue convert(const String& value) {
     switch (value.toInt()) {
@@ -53,6 +68,21 @@ debounce_event::types::PinValue convert(const String& value) {
     }
 }
 
+template<>
+String serialize(const debounce_event::types::PinValue& value) {
+    String result;
+    switch (value) {
+        case debounce_event::types::PinValue::Low:
+            result = "0";
+            break;
+        case debounce_event::types::PinValue::High:
+        default:
+            result = "1";
+            break;
+    }
+    return result;
+}
+
 template<>
 debounce_event::types::PinMode convert(const String& value) {
     switch (value.toInt()) {
@@ -66,6 +96,24 @@ debounce_event::types::PinMode convert(const String& value) {
     }
 }
 
+template<>
+String serialize(const debounce_event::types::PinMode& mode) {
+    String result;
+    switch (mode) {
+        case debounce_event::types::PinMode::InputPullup:
+            result = "1";
+            break;
+        case debounce_event::types::PinMode::InputPulldown:
+            result = "2";
+            break;
+        case debounce_event::types::PinMode::Input:
+        default:
+            result = "0";
+            break;
+    }
+    return result;
+}
+
 } // namespace settings::internal
 } // namespace settings
 

code/espurna/crash.cpp

@@ -152,7 +152,7 @@ void crashSetup() {
     // Minumum of 16 and align for column formatter in crashDump()
     // Maximum of flash sector size minus reserved space at the beginning
     const uint16_t trace_max = constrain(
-        abs((getSetting<int>("sysTraceMax", SAVE_CRASH_STACK_TRACE_MAX) + 15) & -16),
+        abs((getSetting("sysTraceMax", SAVE_CRASH_STACK_TRACE_MAX) + 15) & -16),
         0, (SPI_FLASH_SEC_SIZE - crashUsedSpace())
     );
 

code/espurna/debug.cpp

@@ -29,6 +29,8 @@ char _udp_syslog_header[40] = {0};
 
 bool _debug_enabled = false;
 
+
+
 // -----------------------------------------------------------------------------
 // printf-like debug methods
 // -----------------------------------------------------------------------------
@@ -41,7 +43,7 @@ void _debugSendInternal(const char * message, bool add_timestamp = DEBUG_ADD_TIM
 void _debugSend(const char * format, va_list args) {
 
     char temp[DEBUG_SEND_STRING_BUFFER_SIZE];
-    int len = ets_vsnprintf(temp, sizeof(temp), format, args);
+    int len = vsnprintf(temp, sizeof(temp), format, args);
 
     // strlen(...) + '\0' already in temp buffer, avoid using malloc when possible
     if (len < DEBUG_SEND_STRING_BUFFER_SIZE) {
@@ -54,7 +56,7 @@ void _debugSend(const char * format, va_list args) {
     if (!buffer) {
         return;
     }
-    ets_vsnprintf(buffer, len, format, args);
+    vsnprintf(buffer, len, format, args);
 
     _debugSendInternal(buffer);
     free(buffer);
@@ -282,19 +284,29 @@ void debugSetup() {
 
 }
 
-String _debugLogModeSerialize(DebugLogMode value) {
+namespace settings {
+namespace internal {
+
+template<>
+String serialize(const DebugLogMode& value) {
+    String result;
     switch (value) {
         case DebugLogMode::Disabled:
-            return "0";
+            result = "0";
+            break;
         case DebugLogMode::SkipBoot:
-            return "2";
+            result = "2";
+            break;
         default:
         case DebugLogMode::Enabled:
-            return "1";
+            result = "1";
+            break;
     }
+    return result;
 }
 
-DebugLogMode _debugLogModeDeserialize(const String& value) {
+template<>
+DebugLogMode convert(const String& value) {
     switch (value.toInt()) {
         case 0:
             return DebugLogMode::Disabled;
@@ -306,13 +318,16 @@ DebugLogMode _debugLogModeDeserialize(const String& value) {
     }
 }
 
+}
+}
+
 void debugConfigureBoot() {
     static_assert(
         std::is_same<int, std::underlying_type<DebugLogMode>::type>::value, 
         "should be able to match DebugLogMode with int"
     );
 
-    const auto mode = getSetting<DebugLogMode, _debugLogModeDeserialize>("dbgLogMode", DEBUG_LOG_MODE);
+    const auto mode = getSetting("dbgLogMode", DEBUG_LOG_MODE);
     switch (mode) {
         case DebugLogMode::SkipBoot:
             schedule_function([]() {

code/espurna/influxdb.cpp

@@ -210,7 +210,7 @@ void _idbFlush() {
     if (!wifiConnected()) return;
 
     const auto host = getSetting("idbHost", INFLUXDB_HOST);
-    const auto port = getSetting<uint16_t>("idbPort", INFLUXDB_PORT);
+    const auto port = getSetting("idbPort", static_cast<uint16_t>(INFLUXDB_PORT));
 
     // TODO: should we always store specific pairs like tspk keeps relay / sensor readings?
     //       note that we also send heartbeat data, persistent values should be flagged

code/espurna/main.cpp

@@ -131,7 +131,7 @@ void setup() {
 
     // Return bogus free heap value for broken devices
     // XXX: device is likely to trigger other bugs! tread carefuly
-    wtfHeap(getSetting<int>("wtfHeap", 0));
+    wtfHeap(getSetting("wtfHeap", 0));
 
     // Init Serial, SPIFFS and system check
     systemSetup();

code/espurna/mdns.cpp

@@ -45,7 +45,7 @@ void _mdnsServerStart() {
 void mdnsServerSetup() {
 
     #if WEB_SUPPORT
-        MDNS.addService("http", "tcp", getSetting<uint16_t>("webPort", WEB_PORT));
+        MDNS.addService("http", "tcp", getSetting("webPort", static_cast<uint16_t>(WEB_PORT)));
     #endif
 
     #if TELNET_SUPPORT

code/espurna/mqtt.cpp

@@ -127,7 +127,7 @@ SecureClientConfig _mqtt_sc_config {
         return getSetting("mqttFP", MQTT_SSL_FINGERPRINT);
     },
     []() -> uint16_t {
-        return getSetting<uint16_t>("mqttScMFLN", MQTT_SECURE_CLIENT_MFLN);
+        return getSetting("mqttScMFLN", MQTT_SECURE_CLIENT_MFLN);
     },
     true
 };
@@ -258,7 +258,7 @@ void _mqttConfigure() {
     // Enable only when server is set
     {
         const String server = getSetting("mqttServer", MQTT_SERVER);
-        const auto port = getSetting<uint16_t>("mqttPort", MQTT_PORT);
+        const auto port = getSetting("mqttPort", static_cast<uint16_t>(MQTT_PORT));
         bool enabled = false;
         if (server.length()) {
             enabled = getSetting("mqttEnabled", 1 == MQTT_ENABLED);

code/espurna/sensor.cpp

@@ -201,7 +201,6 @@ Copyright (C) 2016-2019 by Xose Pérez <xose dot perez at gmail dot com>
 
 //--------------------------------------------------------------------------------
 
-
 struct sensor_magnitude_t {
 
     private:
@@ -215,17 +214,19 @@ struct sensor_magnitude_t {
     }
 
     sensor_magnitude_t();
-    sensor_magnitude_t(unsigned char type, unsigned char local, sensor::Unit units, BaseSensor* sensor);
+    sensor_magnitude_t(unsigned char slot, unsigned char index_local, unsigned char type, sensor::Unit units, BaseSensor* sensor);
 
     BaseSensor * sensor;        // Sensor object
     BaseFilter * filter;        // Filter object
 
-    unsigned char type;         // Type of measurement
-    unsigned char local;        // Local index in its provider
-    unsigned char global;       // Global index in its type
-    unsigned char decimals;     // Number of decimals in textual representation
+    unsigned char slot;         // Sensor slot # taken by the magnitude, used to access the measurement
+    unsigned char type;         // Type of measurement, returned by the BaseSensor::type(slot)
+
+    unsigned char index_local;  // N'th magnitude of it's type, local to the sensor
+    unsigned char index_global; // ... and across all of the active sensors
 
     sensor::Unit units;         // Units of measurement
+    unsigned char decimals;     // Number of decimals in textual representation
 
     double last;                // Last raw value from sensor (unfiltered)
     double reported;            // Last reported value
@@ -375,7 +376,7 @@ void _sensorApiResetEnergy(const sensor_magnitude_t& magnitude, const char* payl
     auto* sensor = static_cast<BaseEmonSensor*>(magnitude.sensor);
     auto energy = _sensorParseEnergy(payload);
 
-    sensor->resetEnergy(magnitude.global, energy);
+    sensor->resetEnergy(magnitude.index_global, energy);
 }
 
 sensor::Energy _sensorEnergyTotal(unsigned char index) {
@@ -413,21 +414,21 @@ void _magnitudeSaveEnergyTotal(sensor_magnitude_t& magnitude, bool persistent) {
     const auto energy = sensor->totalEnergy();
 
     // Always save to RTCMEM
-    if (magnitude.global < (sizeof(Rtcmem->energy) / sizeof(*Rtcmem->energy))) {
-        _sensorRtcmemSaveEnergy(magnitude.global, energy);
+    if (magnitude.index_global < (sizeof(Rtcmem->energy) / sizeof(*Rtcmem->energy))) {
+        _sensorRtcmemSaveEnergy(magnitude.index_global, energy);
     }
 
     // Save to EEPROM every '_sensor_save_every' readings
     // Format is `<kwh>+<ws>`, value without `+` is treated as `<ws>`
     if (persistent && _sensor_save_every) {
-        _sensor_save_count[magnitude.global] =
-            (_sensor_save_count[magnitude.global] + 1) % _sensor_save_every;
+        _sensor_save_count[magnitude.index_global] =
+            (_sensor_save_count[magnitude.index_global] + 1) % _sensor_save_every;
 
-        if (0 == _sensor_save_count[magnitude.global]) {
+        if (0 == _sensor_save_count[magnitude.index_global]) {
             const String total = String(energy.kwh.value) + "+" + String(energy.ws.value);
-            setSetting({"eneTotal", magnitude.global}, total);
+            setSetting({"eneTotal", magnitude.index_global}, total);
             #if NTP_SUPPORT
-                if (ntpSynced()) setSetting({"eneTime", magnitude.global}, ntpDateTime());
+                if (ntpSynced()) setSetting({"eneTime", magnitude.index_global}, ntpDateTime());
             #endif
         }
     }
@@ -450,11 +451,12 @@ unsigned char _sensor_report_every = SENSOR_REPORT_EVERY;
 sensor_magnitude_t::sensor_magnitude_t() :
     sensor(nullptr),
     filter(nullptr),
+    slot(0),
     type(0),
-    local(0),
-    global(0),
-    decimals(0),
+    index_local(0),
+    index_global(0),
     units(sensor::Unit::None),
+    decimals(0),
     last(0.0),
     reported(0.0),
     min_change(0.0),
@@ -462,14 +464,15 @@ sensor_magnitude_t::sensor_magnitude_t() :
     correction(0.0)
 {}
 
-sensor_magnitude_t::sensor_magnitude_t(unsigned char type, unsigned char local, sensor::Unit units, BaseSensor* sensor) :
+sensor_magnitude_t::sensor_magnitude_t(unsigned char slot, unsigned char index_local, unsigned char type, sensor::Unit units, BaseSensor* sensor) :
     sensor(sensor),
     filter(nullptr),
+    slot(slot),
     type(type),
-    local(local),
-    global(_counts[type]),
-    decimals(0),
+    index_local(index_local),
+    index_global(_counts[type]),
     units(units),
+    decimals(0),
     last(0.0),
     reported(0.0),
     min_change(0.0),
@@ -784,7 +787,7 @@ sensor::Unit _magnitudeUnitFilter(const sensor_magnitude_t& magnitude, sensor::U
 double _magnitudeProcess(const sensor_magnitude_t& magnitude, double value) {
 
     // Process input (sensor) units and convert to the ones that magnitude specifies as output
-    switch (magnitude.sensor->units(magnitude.local)) {
+    switch (magnitude.sensor->units(magnitude.slot)) {
         case sensor::Unit::Celcius:
             if (magnitude.units == sensor::Unit::Farenheit) {
                 value = (value * 1.8) + 32.0;
@@ -822,8 +825,84 @@ double _magnitudeProcess(const sensor_magnitude_t& magnitude, double value) {
 
 // -----------------------------------------------------------------------------
 
+bool _sensorMatchKeyPrefix(const char * key) {
+    if (strncmp(key, "pwr", 3) == 0) return true;
+    if (strncmp(key, "sns", 3) == 0) return true;
+    if (strncmp(key, "tmp", 3) == 0) return true;
+    if (strncmp(key, "hum", 3) == 0) return true;
+    if (strncmp(key, "ene", 3) == 0) return true;
+    if (strncmp(key, "lux", 3) == 0) return true;
+    return false;
+}
+
+const String _sensorQueryDefault(const String& key) {
+
+    auto get_defaults = [](unsigned char type, BaseSensor* ptr) -> String {
+        if (!ptr) return String();
+        auto* sensor = static_cast<BaseEmonSensor*>(ptr);
+        switch (type) {
+        case MAGNITUDE_CURRENT:
+            return String(sensor->defaultCurrentRatio());
+        case MAGNITUDE_VOLTAGE:
+            return String(sensor->defaultVoltageRatio());
+        case MAGNITUDE_POWER_ACTIVE:
+            return String(sensor->defaultPowerRatio());
+        case MAGNITUDE_ENERGY:
+            return String(sensor->defaultEnergyRatio());
+        default:
+            return String();
+        }
+    };
+
+    auto magnitude_key = [](const sensor_magnitude_t& magnitude) -> settings_key_t {
+        switch (magnitude.type) {
+        case MAGNITUDE_CURRENT:
+            return {"pwrRatioC", magnitude.index_global};
+        case MAGNITUDE_VOLTAGE:
+            return {"pwrRatioV", magnitude.index_global};
+        case MAGNITUDE_POWER_ACTIVE:
+            return {"pwrRatioP", magnitude.index_global};
+        case MAGNITUDE_ENERGY:
+            return {"pwrRatioE", magnitude.index_global};
+        default:
+            return {};
+        }
+    };
+
+    unsigned char type = MAGNITUDE_NONE;
+    BaseSensor* target = nullptr;
+
+    for (auto& magnitude : _magnitudes) {
+        switch (magnitude.type) {
+            case MAGNITUDE_CURRENT:
+            case MAGNITUDE_VOLTAGE:
+            case MAGNITUDE_POWER_ACTIVE:
+            case MAGNITUDE_ENERGY: {
+                auto ratioKey(magnitude_key(magnitude));
+                if (ratioKey.match(key)) {
+                    target = magnitude.sensor;
+                    type = magnitude.type;
+                    goto return_defaults;
+                }
+                break;
+            }
+            default:
+                break;
+        }
+    }
+
+return_defaults:
+
+    return get_defaults(type, target);
+
+}
+
 #if WEB_SUPPORT
 
+bool _sensorWebSocketOnKeyCheck(const char* key, JsonVariant&) {
+    return _sensorMatchKeyPrefix(key);
+}
+
 // Used by modules to generate magnitude_id<->module_id mapping for the WebUI
 
 void sensorWebSocketMagnitudes(JsonObject& root, const String& prefix) {
@@ -848,16 +927,6 @@ void sensorWebSocketMagnitudes(JsonObject& root, const String& prefix) {
     }
 }
 
-bool _sensorWebSocketOnKeyCheck(const char * key, JsonVariant& value) {
-    if (strncmp(key, "pwr", 3) == 0) return true;
-    if (strncmp(key, "sns", 3) == 0) return true;
-    if (strncmp(key, "tmp", 3) == 0) return true;
-    if (strncmp(key, "hum", 3) == 0) return true;
-    if (strncmp(key, "ene", 3) == 0) return true;
-    if (strncmp(key, "lux", 3) == 0) return true;
-    return false;
-}
-
 void _sensorWebSocketOnVisible(JsonObject& root) {
 
     root["snsVisible"] = 1;
@@ -888,14 +957,11 @@ void _sensorWebSocketMagnitudesConfig(JsonObject& root) {
         if (magnitude.type == MAGNITUDE_EVENT) continue;
         ++size;
 
-        index.add<uint8_t>(magnitude.global);
+        // Note: we use int instead of bool to ever so slightly compress json output
+        index.add<uint8_t>(magnitude.index_global);
         type.add<uint8_t>(magnitude.type);
         units.add(_magnitudeUnits(magnitude));
-
-        {
-            String sensor_desc = magnitude.sensor->slot(magnitude.local);
-            description.add(sensor_desc);
-        }
+        description.add(magnitude.sensor->description(magnitude.slot));
 
     }
 
@@ -928,7 +994,7 @@ void _sensorWebSocketSendData(JsonObject& root) {
         #if NTP_SUPPORT
             if ((_sensor_save_every > 0) && (magnitude.type == MAGNITUDE_ENERGY)) {
                 String string = F("Last saved: ");
-                string += getSetting({"eneTime", magnitude.global}, F("(unknown)"));
+                string += getSetting({"eneTime", magnitude.index_global}, F("(unknown)"));
                 info.add(string);
             } else {
                 info.add((uint8_t)0);
@@ -1029,7 +1095,7 @@ void _sensorAPISetup() {
         auto& magnitude = _magnitudes.at(magnitude_id);
 
         String topic = magnitudeTopic(magnitude.type);
-        if (SENSOR_USE_INDEX || (sensor_magnitude_t::counts(magnitude.type) > 1)) topic = topic + "/" + String(magnitude.global);
+        if (SENSOR_USE_INDEX || (sensor_magnitude_t::counts(magnitude.type) > 1)) topic = topic + "/" + String(magnitude.index_global);
 
         api_get_callback_f get_cb = [&magnitude](char * buffer, size_t len) {
             double value = _sensor_realtime ? magnitude.last : magnitude.reported;
@@ -1065,7 +1131,7 @@ void _sensorMqttCallback(unsigned int type, const char* topic, char* payload) {
 
             for (auto& magnitude : _magnitudes) {
                 if (MAGNITUDE_ENERGY != magnitude.type) continue;
-                if (index != magnitude.global) continue;
+                if (index != magnitude.index_global) continue;
                 _sensorApiResetEnergy(magnitude, payload);
                 break;
             }
@@ -1099,8 +1165,8 @@ void _sensorInitCommands() {
             dtostrf(magnitude.reported, 1, magnitude.decimals, reported);
             DEBUG_MSG_P(PSTR("[SENSOR] %2u * %s/%u @ %s (last:%s, reported:%s)\n"),
                 index,
-                magnitudeTopic(magnitude.type).c_str(), magnitude.global,
-                magnitude.sensor->slot(magnitude.local).c_str(),
+                magnitudeTopic(magnitude.type).c_str(), magnitude.index_global,
+                magnitude.sensor->description(magnitude.slot).c_str(),
                 last, reported
             );
         }
@@ -1207,7 +1273,7 @@ void _sensorLoad() {
     #if BMX280_SUPPORT
     {
         // Support up to two sensors with full auto-discovery.
-        const unsigned char number = constrain(getSetting<int>("bmx280Number", BMX280_NUMBER), 1, 2);
+        const unsigned char number = constrain(getSetting("bmx280Number", BMX280_NUMBER), 1, 2);
 
         // For second sensor, if BMX280_ADDRESS is 0x00 then auto-discover
         // otherwise choose the other unnamed sensor address
@@ -1742,7 +1808,7 @@ void _sensorReport(unsigned char index, double value) {
     dtostrf(value, 1, magnitude.decimals, buffer);
 
     #if BROKER_SUPPORT
-        SensorReportBroker::Publish(magnitudeTopic(magnitude.type), magnitude.global, value, buffer);
+        SensorReportBroker::Publish(magnitudeTopic(magnitude.type), magnitude.index_global, value, buffer);
     #endif
 
     #if MQTT_SUPPORT
@@ -1753,9 +1819,9 @@ void _sensorReport(unsigned char index, double value) {
             char topic[32];
             snprintf(topic, sizeof(topic), "%s/%s", SENSOR_ADDRESS_TOPIC, magnitudeTopic(magnitude.type).c_str());
             if (SENSOR_USE_INDEX || (sensor_magnitude_t::counts(magnitude.type) > 1)) {
-                mqttSend(topic, magnitude.global, magnitude.sensor->address(magnitude.local).c_str());
+                mqttSend(topic, magnitude.index_global, magnitude.sensor->address(magnitude.slot).c_str());
             } else {
-                mqttSend(topic, magnitude.sensor->address(magnitude.local).c_str());
+                mqttSend(topic, magnitude.sensor->address(magnitude.slot).c_str());
             }
         #endif // SENSOR_PUBLISH_ADDRESSES
 
@@ -1788,7 +1854,6 @@ void _sensorCallback(unsigned char i, unsigned char type, double value) {
 void _sensorInit() {
 
     _sensors_ready = true;
-    _sensor_save_every = 0;
 
     for (unsigned char i=0; i<_sensors.size(); i++) {
 
@@ -1808,14 +1873,19 @@ void _sensorInit() {
         for (unsigned char magnitude_index = 0; magnitude_index < _sensors[i]->count(); ++magnitude_index) {
 
             const auto magnitude_type = _sensors[i]->type(magnitude_index);
+            const auto magnitude_local = _sensors[i]->local(magnitude_type);
             _magnitudes.emplace_back(
-                magnitude_type,               // specific type of the magnitude
-                magnitude_index,              // index local to the sensor
-                sensor::Unit::None,           // set up later, in configuration
-                _sensors[i]                   // bind the sensor to allow us to reference it later
+                magnitude_index,     // id of the magnitude, unique to the sensor
+                magnitude_local,     // index_local, # of the magnitude
+                magnitude_type,      // specific type of the magnitude
+                sensor::Unit::None,  // set up later, in configuration
+                _sensors[i]          // bind the sensor to allow us to reference it later
             );
 
-            if (MAGNITUDE_ENERGY == magnitude_type) {
+            if (_sensorIsEmon(_sensors[i]) && (MAGNITUDE_ENERGY == magnitude_type)) {
+                const auto index_global = _magnitudes.back().index_global;
+                auto* sensor = static_cast<BaseEmonSensor*>(_sensors[i]);
+                sensor->resetEnergy(magnitude_local, _sensorEnergyTotal(index_global));
                 _sensor_save_count.push_back(0);
             }
 
@@ -1846,36 +1916,6 @@ void _sensorInit() {
             break;
         }
 
-        // TODO: compatibility proxy, fetch global key before indexed
-        auto get_ratio = [](const char* key, unsigned char index, double default_value) -> double {
-            return getSetting({key, index}, getSetting(key, default_value));
-        };
-
-        if (_sensorIsEmon(_sensors[i])) {
-
-            auto* sensor = static_cast<BaseEmonSensor*>(_sensors[i]);
-
-            for (size_t index = 0; index < sensor->countDevices(); ++index) {
-                sensor->resetEnergy(index, _sensorEnergyTotal(index));
-                sensor->setCurrentRatio(
-                    index, get_ratio("pwrRatioC", index, sensor->getCurrentRatio(index))
-                );
-                sensor->setVoltageRatio(
-                    index, get_ratio("pwrRatioV", index, sensor->getVoltageRatio(index))
-                );
-                sensor->setPowerRatio(
-                    index, get_ratio("pwrRatioP", index, sensor->getPowerRatio(index))
-                );
-                sensor->setEnergyRatio(
-                    index, get_ratio("pwrRatioE", index, sensor->getEnergyRatio(index))
-                );
-                sensor->setVoltage(
-                    index, get_ratio("pwrVoltage", index, sensor->getVoltage(index))
-                );
-            }
-
-        }
-
     }
 
 }
@@ -1893,6 +1933,11 @@ sensor::Unit convert(const String& string) {
     return sensor::Unit::None;
 }
 
+template <>
+String serialize(const sensor::Unit& unit) {
+    return String(static_cast<int>(unit));
+}
+
 } // ns settings::internal
 } // ns settings
 
@@ -1913,7 +1958,7 @@ void _sensorConfigure() {
     const auto hum_min_delta = getSetting("humMinDelta", HUMIDITY_MIN_CHANGE);
     const auto ene_max_delta = getSetting("eneMaxDelta", ENERGY_MAX_CHANGE);
 
-    // Specific sensor settings
+    // Apply settings based on sensor type
     for (unsigned char index = 0; index < _sensors.size(); ++index) {
 
         #if MICS2710_SUPPORT || MICS5525_SUPPORT
@@ -1974,8 +2019,6 @@ void _sensorConfigure() {
                 sensor->resetRatios();
             }
 
-            sensor->setEnergyRatio(getSetting("pwrRatioE", sensor->getEnergyRatio()));
-
         } // is emon?
 
     }
@@ -1997,34 +2040,73 @@ void _sensorConfigure() {
 
             auto& magnitude = _magnitudes.at(index);
 
+            // process emon-specific settings first. ensure that settings use global index and we access sensor with the local one
+            if (_sensorIsEmon(magnitude.sensor)) {
+                // TODO: compatibility proxy, fetch global key before indexed
+                auto get_ratio = [](const char* key, unsigned char index, double default_value) -> double {
+                    return getSetting({key, index}, getSetting(key, default_value));
+                };
+
+                auto* sensor = static_cast<BaseEmonSensor*>(magnitude.sensor);
+
+                switch (magnitude.type) {
+                case MAGNITUDE_CURRENT:
+                    sensor->setCurrentRatio(
+                        magnitude.index_local, get_ratio("pwrRatioC", magnitude.index_global, sensor->defaultCurrentRatio())
+                    );
+                    break;
+                case MAGNITUDE_POWER_ACTIVE:
+                    sensor->setPowerRatio(
+                        magnitude.index_local, get_ratio("pwrRatioP", magnitude.index_global, sensor->defaultPowerRatio())
+                    );
+                    break;
+                case MAGNITUDE_VOLTAGE:
+                    sensor->setVoltageRatio(
+                        magnitude.index_local, get_ratio("pwrRatioV", magnitude.index_global, sensor->defaultVoltageRatio())
+                    );
+                    sensor->setVoltage(
+                        magnitude.index_local, get_ratio("pwrVoltage", magnitude.index_global, sensor->defaultVoltage())
+                    );
+                    break;
+                case MAGNITUDE_ENERGY:
+                    sensor->setEnergyRatio(
+                        magnitude.index_local, get_ratio("pwrRatioE", magnitude.index_global, sensor->defaultEnergyRatio())
+                    );
+                    break;
+                default:
+                    break;
+                }
+            }
+
+            // adjust type-specific units (TODO: try to adjust settings to use type prefixes?)
             switch (magnitude.type) {
                 case MAGNITUDE_TEMPERATURE:
                     magnitude.units = _magnitudeUnitFilter(
                         magnitude,
-                        getSetting({"tmpUnits", magnitude.global}, tmpUnits)
+                        getSetting({"tmpUnits", magnitude.index_global}, tmpUnits)
                     );
-                    magnitude.correction = getSetting({"tmpCorrection", magnitude.global}, tmpCorrection);
+                    magnitude.correction = getSetting({"tmpCorrection", magnitude.index_global}, tmpCorrection);
                     break;
                 case MAGNITUDE_HUMIDITY:
-                    magnitude.correction = getSetting({"humCorrection", magnitude.global}, humCorrection);
+                    magnitude.correction = getSetting({"humCorrection", magnitude.index_global}, humCorrection);
                     break;
                 case MAGNITUDE_POWER_ACTIVE:
                     magnitude.units = _magnitudeUnitFilter(
                         magnitude,
-                        getSetting({"pwrUnits", magnitude.global}, pwrUnits)
+                        getSetting({"pwrUnits", magnitude.index_global}, pwrUnits)
                     );
                     break;
                 case MAGNITUDE_ENERGY:
                     magnitude.units = _magnitudeUnitFilter(
                         magnitude,
-                        getSetting({"eneUnits", magnitude.global}, eneUnits)
+                        getSetting({"eneUnits", magnitude.index_global}, eneUnits)
                     );
                     break;
                 case MAGNITUDE_LUX:
-                    magnitude.correction = getSetting({"luxCorrection", magnitude.global}, luxCorrection);
+                    magnitude.correction = getSetting({"luxCorrection", magnitude.index_global}, luxCorrection);
                     break;
                 default:
-                    magnitude.units = magnitude.sensor->units(magnitude.local);
+                    magnitude.units = magnitude.sensor->units(magnitude.slot);
                     break;
             }
 
@@ -2037,6 +2119,7 @@ void _sensorConfigure() {
 
             // adjust min & max change delta value to trigger report
             // TODO: find a proper way to extend this to min/max of any magnitude
+            // TODO: we can't use index_global b/c we don't specify type in the setting
             {
                 auto min_default = 0.0;
                 auto max_default = 0.0;
@@ -2061,7 +2144,7 @@ void _sensorConfigure() {
 
             // in case we don't save energy periodically, purge existing value in ram & settings
             if ((MAGNITUDE_ENERGY == magnitude.type) && (0 == _sensor_save_every)) {
-                _sensorResetEnergyTotal(magnitude.global);
+                _sensorResetEnergyTotal(magnitude.index_global);
             }
 
         }
@@ -2086,7 +2169,7 @@ unsigned char magnitudeCount() {
 String magnitudeName(unsigned char index) {
     if (index < _magnitudes.size()) {
         sensor_magnitude_t magnitude = _magnitudes[index];
-        return magnitude.sensor->slot(magnitude.local);
+        return magnitude.sensor->description(magnitude.slot);
     }
     return String();
 }
@@ -2107,7 +2190,7 @@ double magnitudeValue(unsigned char index) {
 
 unsigned char magnitudeIndex(unsigned char index) {
     if (index < _magnitudes.size()) {
-        return int(_magnitudes[index].global);
+        return int(_magnitudes[index].index_global);
     }
     return 0;
 }
@@ -2117,7 +2200,7 @@ String magnitudeTopicIndex(unsigned char index) {
     if (index < _magnitudes.size()) {
         sensor_magnitude_t magnitude = _magnitudes[index];
         if (SENSOR_USE_INDEX || (sensor_magnitude_t::counts(magnitude.type) > 1)) {
-            snprintf(topic, sizeof(topic), "%s/%u", magnitudeTopic(magnitude.type).c_str(), magnitude.global);
+            snprintf(topic, sizeof(topic), "%s/%u", magnitudeTopic(magnitude.type).c_str(), magnitude.index_global);
         } else {
             snprintf(topic, sizeof(topic), "%s", magnitudeTopic(magnitude.type).c_str());
         }
@@ -2133,7 +2216,7 @@ void _sensorBackwards() {
     moveSetting("powerUnits", "pwrUnits");
     moveSetting("energyUnits", "eneUnits");
 
-    // Energy is now indexed (based on magnitude.global)
+    // Energy is now indexed (based on magnitude.index_global)
     moveSetting("eneTotal", "eneTotal0");
 
 	// Update PZEM004T energy total across multiple devices
@@ -2165,6 +2248,15 @@ void sensorSetup() {
     // Configure based on settings
     _sensorConfigure();
 
+    // Allow us to query key default
+    settingsRegisterDefaults({
+        [](const char* key) -> bool {
+            if (strncmp(key, "pwr", 3) == 0) return true;
+            return false;
+        },
+        _sensorQueryDefault
+    });
+
     // Websockets integration, send sensor readings and configuration
     #if WEB_SUPPORT
         wsRegister()
@@ -2242,7 +2334,7 @@ void sensorLoop() {
                 // Instant value
                 // -------------------------------------------------------------
 
-                value_raw = magnitude.sensor->value(magnitude.local);
+                value_raw = magnitude.sensor->value(magnitude.slot);
 
                 // Completely remove spurious values if relay is OFF
                 #if RELAY_SUPPORT && SENSOR_POWER_CHECK_STATUS
@@ -2290,7 +2382,7 @@ void sensorLoop() {
                 {
                     char buffer[64];
                     dtostrf(value_show, 1, magnitude.decimals, buffer);
-                    SensorReadBroker::Publish(magnitudeTopic(magnitude.type), magnitude.global, value_show, buffer);
+                    SensorReadBroker::Publish(magnitudeTopic(magnitude.type), magnitude.index_global, value_show, buffer);
                 }
                 #endif
 
@@ -2303,7 +2395,7 @@ void sensorLoop() {
                     char buffer[64];
                     dtostrf(value_show, 1, magnitude.decimals, buffer);
                     DEBUG_MSG_P(PSTR("[SENSOR] %s - %s: %s%s\n"),
-                        magnitude.sensor->slot(magnitude.local).c_str(),
+                        magnitude.sensor->description(magnitude.slot).c_str(),
                         magnitudeTopic(magnitude.type).c_str(),
                         buffer,
                         _magnitudeUnits(magnitude).c_str()

code/espurna/sensors/ADE7953Sensor.h

@@ -75,11 +75,10 @@ class ADE7953Sensor : public I2CSensor<BaseEmonSensor> {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 
-
         // Pre-read hook (usually to populate registers with up-to-date data)
         void pre() {
             uint32_t active_power1 = 0;
@@ -150,6 +149,12 @@ class ADE7953Sensor : public I2CSensor<BaseEmonSensor> {
             return 0;
         }
 
+        // Convert slot # to a magnitude #
+        unsigned char local(unsigned char index) override {
+            if (index == 0) { return 0; }        // common voltage
+            return (index - 1) / countDevices(); // device { energy, current, active power }
+        }
+
         // Type for slot # index
         unsigned char type(unsigned char index) {
             if (index == 0) return MAGNITUDE_VOLTAGE;

code/espurna/sensors/AM2320Sensor.h

@@ -65,7 +65,7 @@ class AM2320Sensor : public I2CSensor<> {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/AnalogSensor.h

@@ -78,7 +78,7 @@ class AnalogSensor : public BaseAnalogSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/BaseEmonSensor.h

@@ -67,6 +67,10 @@ class BaseEmonSensor : public BaseSensor {
         }
 
         // --- configuration ---
+
+        virtual double defaultVoltage() {
+            return 0.0;
+        }
         
         // when sensor needs explicit mains voltage value
         virtual void setVoltage(double) {}
@@ -74,7 +78,7 @@ class BaseEmonSensor : public BaseSensor {
             setVoltage(value);
         }
         virtual double getVoltage() {
-            return 0.0;
+            return defaultVoltage();
         }
         virtual double getVoltage(unsigned char index) {
             return getVoltage();
@@ -100,18 +104,33 @@ class BaseEmonSensor : public BaseSensor {
             setEnergyRatio(value);
         }
 
+        // Generic ratio configuration, default is a
+        // no-op and must be implemented by the sensor class
+        virtual double defaultCurrentRatio() const {
+            return 0.0;
+        }
+        virtual double defaultVoltageRatio() const {
+            return 0.0;
+        }
+        virtual double defaultPowerRatio() const {
+            return 0.0;
+        }
+        virtual double defaultEnergyRatio() const {
+            return 0.0;
+        }
+
         // when sensor implements a single device
         virtual double getCurrentRatio() {
-            return 0.0;
+            return defaultCurrentRatio();
         }
         virtual double getVoltageRatio() {
-            return 0.0;
+            return defaultVoltageRatio();
         }
         virtual double getPowerRatio() {
-            return 0.0;
+            return defaultPowerRatio();
         }
         virtual double getEnergyRatio() {
-            return 0.0;
+            return defaultEnergyRatio();
         }
 
         // when sensor implements more than one device
@@ -132,7 +151,16 @@ class BaseEmonSensor : public BaseSensor {
         virtual void expectedVoltage(unsigned int value) {}
         virtual void expectedPower(unsigned int value) {}
 
-        virtual void resetCalibration(double value) {}
+        virtual void expectedCurrent(unsigned char index, double value) {
+            expectedCurrent(value);
+        }
+        virtual void expectedVoltage(unsigned char index, unsigned int value) {
+            expectedVoltage(value);
+        }
+        virtual void expectedPower(unsigned char index, unsigned int value) {
+            expectedPower(value);
+        }
+
         virtual void resetRatios() {}
 
     protected:

code/espurna/sensors/BaseSensor.h

@@ -39,12 +39,12 @@ class BaseSensor {
         // Descriptive name of the sensor
         virtual String description() = 0;
 
+        // Descriptive name of the slot # index
+        virtual String description(unsigned char index) = 0;
+
         // Address of the sensor (it could be the GPIO or I2C address)
         virtual String address(unsigned char index) = 0;
 
-        // Descriptive name of the slot # index
-        virtual String slot(unsigned char index) = 0;
-
         // Type of sensor
         virtual unsigned char type() { return sensor::type::Base; }
 
@@ -84,6 +84,9 @@ class BaseSensor {
         // Number of available slots
         unsigned char count() { return _count; }
 
+        // Convert slot # index to a magnitude # index
+        virtual unsigned char local(unsigned char slot) { return 0; }
+
         // Hook for event callback
         void onEvent(TSensorCallback fn) { _callback = fn; };
 

code/espurna/sensors/CSE7766Sensor.h

@@ -59,50 +59,64 @@ class CSE7766Sensor : public BaseEmonSensor {
 
         // ---------------------------------------------------------------------
 
-        void expectedCurrent(double expected) {
+        void expectedCurrent(double expected) override {
             if ((expected > 0) && (_current > 0)) {
                 _ratioC = _ratioC * (expected / _current);
             }
         }
 
-        void expectedVoltage(unsigned int expected) {
+        void expectedVoltage(unsigned int expected) override {
             if ((expected > 0) && (_voltage > 0)) {
                 _ratioV = _ratioV * (expected / _voltage);
             }
         }
 
-        void expectedPower(unsigned int expected) {
+        void expectedPower(unsigned int expected) override {
             if ((expected > 0) && (_active > 0)) {
                 _ratioP = _ratioP * (expected / _active);
             }
         }
 
-        void setCurrentRatio(double value) {
+        double defaultCurrentRatio() const override {
+            return 1.0;
+        }
+
+        double defaultVoltageRatio() const override {
+            return 1.0;
+        }
+
+        double defaultPowerRatio() const override {
+            return 1.0;
+        }
+
+        void setCurrentRatio(double value) override {
             _ratioC = value;
         };
 
-        void setVoltageRatio(double value) {
+        void setVoltageRatio(double value) override {
             _ratioV = value;
         };
 
-        void setPowerRatio(double value) {
+        void setPowerRatio(double value) override {
             _ratioP = value;
         };
 
-        double getCurrentRatio() {
+        double getCurrentRatio() override {
             return _ratioC;
         };
 
-        double getVoltageRatio() {
+        double getVoltageRatio() override {
             return _ratioV;
         };
 
-        double getPowerRatio() {
+        double getPowerRatio() override {
             return _ratioP;
         };
 
-        void resetCalibration() {
-            _ratioC = _ratioV = _ratioP = 1.0;
+        void resetRatios() override {
+            _ratioC = defaultCurrentRatio();
+            _ratioV = defaultVoltageRatio();
+            _ratioP = defaultPowerRatio();
         }
 
         // ---------------------------------------------------------------------
@@ -112,6 +126,8 @@ class CSE7766Sensor : public BaseEmonSensor {
         // Initialization method, must be idempotent
         void begin() {
 
+            resetRatios();
+
             if (!_dirty) return;
 
             if (_serial) delete _serial;
@@ -141,7 +157,7 @@ class CSE7766Sensor : public BaseEmonSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 
@@ -387,9 +403,9 @@ class CSE7766Sensor : public BaseEmonSensor {
         double _voltage = 0;
         double _current = 0;
 
-        double _ratioV = 1.0;
-        double _ratioC = 1.0;
-        double _ratioP = 1.0;
+        double _ratioV;
+        double _ratioC;
+        double _ratioP;
 
         unsigned char _data[24];
 

code/espurna/sensors/DHTSensor.h

@@ -132,7 +132,7 @@ class DHTSensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/DallasSensor.h

@@ -239,7 +239,7 @@ class DallasSensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             if (index < _count) {
                 char buffer[40];
                 uint8_t * address = _devices[index].address;

code/espurna/sensors/DigitalSensor.h

@@ -70,7 +70,7 @@ class DigitalSensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/ECH1560Sensor.h

@@ -94,7 +94,7 @@ class ECH1560Sensor : public BaseEmonSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/EZOPHSensor.h

@@ -81,7 +81,7 @@ class EZOPHSensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/EmonADC121Sensor.h

@@ -119,7 +119,7 @@ class EmonADC121Sensor : public EmonSensor {
 
         // Current value for slot # index
         double value(unsigned char index) {
-            unsigned char channel = index / _magnitudes;
+            unsigned char channel = local(index);
             unsigned char i=0;
             #if EMON_REPORT_CURRENT
                 if (index == i++) return _current[channel];

code/espurna/sensors/EmonADS1X15Sensor.h

@@ -146,6 +146,11 @@ class EmonADS1X15Sensor : public EmonSensor {
         // Sensor API
         // ---------------------------------------------------------------------
 
+        // Convert slot # index to a magnitude # index
+        unsigned char local(unsigned char index) override {
+            return (_ports) ? (index / _ports) : 0u;
+        }
+
         // Initialization method, must be idempotent
         void begin() {
 
@@ -194,7 +199,7 @@ class EmonADS1X15Sensor : public EmonSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             char buffer[35];
             unsigned char channel = getChannel(index % _ports);
             snprintf(buffer, sizeof(buffer), "EMON @ ADS1%d15 (A%d) @ I2C (0x%02X)", _type == ADS1X15_CHIP_ADS1015 ? 0 : 1, channel, _address);

code/espurna/sensors/EmonSensor.h

@@ -41,7 +41,9 @@ class EmonSensor : public I2CSensor<BaseEmonSensor> {
 
         }
 
-        void expectedPower(unsigned char channel, unsigned int expected) {
+        // ---------------------------------------------------------------------
+
+        void expectedPower(unsigned char channel, unsigned int expected) override {
             if (channel >= _channels) return;
             unsigned int actual = _current[channel] * _voltage;
             if (actual == 0) return;
@@ -51,9 +53,7 @@ class EmonSensor : public I2CSensor<BaseEmonSensor> {
             _dirty = true;
         }
 
-        // ---------------------------------------------------------------------
-
-        void setVoltage(double voltage) {
+        void setVoltage(double voltage) override {
             if (_voltage == voltage) return;
             _voltage = voltage;
             _dirty = true;
@@ -65,7 +65,11 @@ class EmonSensor : public I2CSensor<BaseEmonSensor> {
             _dirty = true;
         }
 
-        void setCurrentRatio(unsigned char channel, double current_ratio) {
+        double defaultCurrentRatio() const override {
+            return EMON_CURRENT_RATIO;
+        }
+
+        void setCurrentRatio(unsigned char channel, double current_ratio) override {
             if (channel >= _channels) return;
             if (_current_ratio[channel] == current_ratio) return;
             _current_ratio[channel] = current_ratio;
@@ -73,13 +77,15 @@ class EmonSensor : public I2CSensor<BaseEmonSensor> {
             _dirty = true;
         }
 
-        void resetRatios() {
-            setCurrentRatio(0, EMON_CURRENT_RATIO);
+        void resetRatios() override {
+            for (unsigned char channel = 0; channel < _channels; ++channel) {
+                setCurrentRatio(channel, defaultCurrentRatio());
+            }
         }
 
         // ---------------------------------------------------------------------
 
-        double getVoltage() {
+        double getVoltage() override {
             return _voltage;
         }
 
@@ -87,12 +93,12 @@ class EmonSensor : public I2CSensor<BaseEmonSensor> {
             return _reference;
         }
 
-        double getCurrentRatio(unsigned char channel) {
+        double getCurrentRatio(unsigned char channel) override {
             if (channel >= _channels) return 0;
             return _current_ratio[channel];
         }
 
-        unsigned char getChannels() {
+        size_t countDevices() override {
             return _channels;
         }
 
@@ -128,6 +134,11 @@ class EmonSensor : public I2CSensor<BaseEmonSensor> {
 
         }
 
+        // Convert slot # index to a magnitude # index
+        unsigned char local(unsigned char index) override {
+            return (_magnitudes) ? (index / _magnitudes) : 0u;
+        }
+
     protected:
 
         // ---------------------------------------------------------------------

code/espurna/sensors/EventSensor.h

@@ -107,7 +107,7 @@ class EventSensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/GUVAS12SDSensor.h

@@ -91,7 +91,7 @@ class GUVAS12SDSensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/GeigerSensor.h

@@ -94,7 +94,7 @@ String description() {
 }
 
 // Descriptive name of the slot # index
-String slot(unsigned char index) {
+String description(unsigned char index) {
         char buffer[30];
         unsigned char i=0;
             #if GEIGER_REPORT_CPM

code/espurna/sensors/HDC1080Sensor.h

@@ -57,7 +57,7 @@ class HDC1080Sensor : public I2CSensor<> {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/HLW8012Sensor.h

@@ -33,22 +33,6 @@ class HLW8012Sensor : public BaseEmonSensor {
             delete _hlw8012;
         }
 
-        void expectedCurrent(double expected) {
-            _hlw8012->expectedCurrent(expected);
-        }
-
-        void expectedVoltage(unsigned int expected) {
-            _hlw8012->expectedVoltage(expected);
-        }
-
-        void expectedPower(unsigned int expected) {
-            _hlw8012->expectedActivePower(expected);
-        }
-
-        void resetRatios() {
-            _hlw8012->resetMultipliers();
-        }
-
         // ---------------------------------------------------------------------
 
         void setSEL(unsigned char sel) {
@@ -73,18 +57,62 @@ class HLW8012Sensor : public BaseEmonSensor {
             _sel_current = value;
         }
 
-        void setCurrentRatio(double value) {
+        // ---------------------------------------------------------------------
+
+        void expectedCurrent(double expected) override {
+            _hlw8012->expectedCurrent(expected);
+        }
+
+        void expectedVoltage(unsigned int expected) override {
+            _hlw8012->expectedVoltage(expected);
+        }
+
+        void expectedPower(unsigned int expected) override {
+            _hlw8012->expectedActivePower(expected);
+        }
+
+        double defaultCurrentRatio() const override {
+            return HLW8012_CURRENT_RATIO;
+        }
+
+        double defaultVoltageRatio() const override {
+            return HLW8012_VOLTAGE_RATIO;
+        }
+
+        double defaultPowerRatio() const override {
+            return HLW8012_POWER_RATIO;
+        }
+
+        void resetRatios() override {
+            _hlw8012->setCurrentMultiplier(_initialRatioC);
+            _hlw8012->setVoltageMultiplier(_initialRatioV);
+            _hlw8012->setPowerMultiplier(_initialRatioP);
+        }
+
+        void setCurrentRatio(double value) override {
             _hlw8012->setCurrentMultiplier(value);
         };
 
-        void setVoltageRatio(double value) {
+        void setVoltageRatio(double value) override {
             _hlw8012->setVoltageMultiplier(value);
         };
 
-        void setPowerRatio(double value) {
+        void setPowerRatio(double value) override {
             _hlw8012->setPowerMultiplier(value);
         };
 
+        double getCurrentRatio() override {
+            return _hlw8012->getCurrentMultiplier();
+        };
+
+        double getVoltageRatio() override {
+            return _hlw8012->getVoltageMultiplier();
+        };
+
+        double getPowerRatio() override {
+            return _hlw8012->getPowerMultiplier();
+        };
+
         // ---------------------------------------------------------------------
 
         unsigned char getSEL() {
@@ -103,18 +131,6 @@ class HLW8012Sensor : public BaseEmonSensor {
             return _sel_current;
         }
 
-        double getCurrentRatio() {
-            return _hlw8012->getCurrentMultiplier();
-        };
-
-        double getVoltageRatio() {
-            return _hlw8012->getVoltageMultiplier();
-        };
-
-        double getPowerRatio() {
-            return _hlw8012->getPowerMultiplier();
-        };
-
         // ---------------------------------------------------------------------
         // Sensors API
         // ---------------------------------------------------------------------
@@ -135,17 +151,8 @@ class HLW8012Sensor : public BaseEmonSensor {
                 _hlw8012->begin(_cf, _cf1, _sel, _sel_current, false, 1000000);
             #endif
 
-            // These values are used to calculate current, voltage and power factors as per datasheet formula
-            // These are the nominal values for the Sonoff POW resistors:
-            // * The CURRENT_RESISTOR is the 1milliOhm copper-manganese resistor in series with the main line
-            // * The VOLTAGE_RESISTOR_UPSTREAM are the 5 470kOhm resistors in the voltage divider that feeds the V2P pin in the HLW8012
-            // * The VOLTAGE_RESISTOR_DOWNSTREAM is the 1kOhm resistor in the voltage divider that feeds the V2P pin in the HLW8012
-            _hlw8012->setResistors(HLW8012_CURRENT_R, HLW8012_VOLTAGE_R_UP, HLW8012_VOLTAGE_R_DOWN);
-
-            // Also, adjust with ratio values that could be set in hardware profile
-            if (HLW8012_CURRENT_RATIO > 0.0) _hlw8012->setCurrentMultiplier(HLW8012_CURRENT_RATIO);
-            if (HLW8012_VOLTAGE_RATIO > 0.0) _hlw8012->setVoltageMultiplier(HLW8012_VOLTAGE_RATIO);
-            if (HLW8012_POWER_RATIO > 0.0) _hlw8012->setPowerMultiplier(HLW8012_POWER_RATIO);
+            // Adjust with ratio values that could be set in the hardware profile
+            _defaultRatios();
 
             // Handle interrupts
             #if HLW8012_USE_INTERRUPTS && (!HLW8012_WAIT_FOR_WIFI)
@@ -165,7 +172,7 @@ class HLW8012Sensor : public BaseEmonSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 
@@ -232,6 +239,25 @@ class HLW8012Sensor : public BaseEmonSensor {
 
     protected:
 
+        void _defaultRatios() {
+            // These values are used to calculate current, voltage and power factors as per datasheet formula
+            // These are the nominal values for the Sonoff POW resistors:
+            // * The CURRENT_RESISTOR is the 1milliOhm copper-manganese resistor in series with the main line
+            // * The VOLTAGE_RESISTOR_UPSTREAM are the 5 470kOhm resistors in the voltage divider that feeds the V2P pin in the HLW8012
+            // * The VOLTAGE_RESISTOR_DOWNSTREAM is the 1kOhm resistor in the voltage divider that feeds the V2P pin in the HLW8012
+            _hlw8012->setResistors(HLW8012_CURRENT_R, HLW8012_VOLTAGE_R_UP, HLW8012_VOLTAGE_R_DOWN);
+
+            // Multipliers are already set, but we might have changed default values via the hardware profile
+            if (defaultCurrentRatio() > 0.0) _hlw8012->setCurrentMultiplier(defaultCurrentRatio());
+            if (defaultVoltageRatio() > 0.0) _hlw8012->setVoltageMultiplier(defaultVoltageRatio());
+            if (defaultPowerRatio() > 0.0) _hlw8012->setPowerMultiplier(defaultPowerRatio());
+
+            // Preserve ratios as a fallback
+            _initialRatioC = getCurrentRatio();
+            _initialRatioV = getVoltageRatio();
+            _initialRatioP = getPowerRatio();
+        }
+
         // ---------------------------------------------------------------------
         // Interrupt management
         // ---------------------------------------------------------------------
@@ -276,6 +302,10 @@ class HLW8012Sensor : public BaseEmonSensor {
 
         // ---------------------------------------------------------------------
 
+        double _initialRatioC;
+        double _initialRatioV;
+        double _initialRatioP;
+
         unsigned char _sel = GPIO_NONE;
         unsigned char _cf = GPIO_NONE;
         unsigned char _cf1 = GPIO_NONE;

code/espurna/sensors/I2CSensor.h

@@ -47,7 +47,7 @@ class I2CSensor : public T {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return static_cast<T*>(this)->description();
         };
 

code/espurna/sensors/LDRSensor.h

@@ -125,7 +125,7 @@ class LDRSensor : public AnalogSensor {
 		}
 
 		// Descriptive name of the slot # index
-		String slot(unsigned char index) {
+		String description(unsigned char index) {
 			return description();
 		}
 

code/espurna/sensors/MAX6675Sensor.h

@@ -95,7 +95,7 @@ class MAX6675Sensor : public BaseSensor {
 
         // Address of the device
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             if (index < _count) {
             //    char buffer[40];
             //    uint8_t * address = _devices[index].address;

code/espurna/sensors/MHZ19Sensor.h

@@ -94,7 +94,7 @@ class MHZ19Sensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/MICS2710Sensor.h

@@ -90,7 +90,7 @@ class MICS2710Sensor : public BaseAnalogSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/MICS5525Sensor.h

@@ -62,7 +62,7 @@ class MICS5525Sensor : public BaseAnalogSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/NTCSensor.h

@@ -61,7 +61,7 @@ class NTCSensor : public AnalogSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         }
 

code/espurna/sensors/PMSX003Sensor.h

@@ -247,7 +247,7 @@ class PMSX003Sensor : public BaseSensor, PMSX003 {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             char buffer[36] = {0};
             if (_soft) {
                 snprintf(buffer, sizeof(buffer), "%d @ %s @ SwSerial(%u,%u)", int(index + 1), pms_specs[_type].name, _pin_rx, _pin_tx);

code/espurna/sensors/PZEM004TSensor.h

@@ -89,21 +89,23 @@ class PZEM004TSensor : public BaseEmonSensor {
             return PZEM004TSensor::instance;
         }
 
+        // ---------------------------------------------------------------------
+
         // We can't modify PZEM values, just ignore this
-        void resetEnergy() {}
-        void resetEnergy(unsigned char) {}
-        void resetEnergy(unsigned char, sensor::Energy) {}
+        void resetEnergy() override {}
+        void resetEnergy(unsigned char) override {}
+        void resetEnergy(unsigned char, sensor::Energy) override {}
 
         // Override Base methods that deal with _energy[]
-        size_t countDevices() {
+        size_t countDevices() override {
             return _addresses.size();
         }
 
-        double getEnergy(unsigned char index) {
+        double getEnergy(unsigned char index) override {
             return _readings[index].energy;
         }
 
-        sensor::Energy totalEnergy(unsigned char index) {
+        sensor::Energy totalEnergy(unsigned char index) override {
             return getEnergy(index);
         }
 
@@ -210,8 +212,8 @@ class PZEM004TSensor : public BaseEmonSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
-            int dev = index / PZ_MAGNITUDE_COUNT;
+        String description(unsigned char index) {
+            auto dev = local(index);
             char buffer[25];
             snprintf(buffer, sizeof(buffer), "(%u/%s)", dev, getAddress(dev).c_str());
             return description() + String(buffer);
@@ -219,14 +221,17 @@ class PZEM004TSensor : public BaseEmonSensor {
 
         // Address of the sensor (it could be the GPIO or I2C address)
         String address(unsigned char index) {
-            int dev = index / PZ_MAGNITUDE_COUNT;
-            return _addresses[dev].toString();
+            return _addresses[local(index)].toString();
+        }
+
+        // Convert slot # to a magnitude #
+        unsigned char local(unsigned char index) override {
+            return index / PZ_MAGNITUDE_COUNT;
         }
 
         // Type for slot # index
         unsigned char type(unsigned char index) {
-            int dev = index / PZ_MAGNITUDE_COUNT;
-            index = index - (dev * PZ_MAGNITUDE_COUNT);
+            index = index - (local(index) * PZ_MAGNITUDE_COUNT);
             if (index == PZ_MAGNITUDE_CURRENT_INDEX)      return MAGNITUDE_CURRENT;
             if (index == PZ_MAGNITUDE_VOLTAGE_INDEX)      return MAGNITUDE_VOLTAGE;
             if (index == PZ_MAGNITUDE_POWER_ACTIVE_INDEX) return MAGNITUDE_POWER_ACTIVE;

code/espurna/sensors/PulseMeterSensor.h

@@ -82,7 +82,7 @@ class PulseMeterSensor : public BaseEmonSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/SDS011Sensor.h

@@ -83,7 +83,7 @@ class SDS011Sensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/SI1145Sensor.h

@@ -51,7 +51,7 @@ class SI1145Sensor : public I2CSensor<> {
          }
 
          // Descriptive name of the slot # index
-         String slot(unsigned char index) {
+         String description(unsigned char index) {
              return description();
          };
 

code/espurna/sensors/SI7021Sensor.h

@@ -63,7 +63,7 @@ class SI7021Sensor : public I2CSensor<> {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/SenseAirSensor.h

@@ -180,7 +180,7 @@ class SenseAirSensor : public BaseSensor, SenseAir {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         }
 

code/espurna/sensors/SonarSensor.h

@@ -85,7 +85,7 @@ class SonarSensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/T6613Sensor.h

@@ -89,7 +89,7 @@ class T6613Sensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/TMP3XSensor.h

@@ -56,7 +56,7 @@ class TMP3XSensor : public BaseSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/V9261FSensor.h

@@ -84,7 +84,7 @@ class V9261FSensor : public BaseEmonSensor {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/VEML6075Sensor.h

@@ -50,7 +50,7 @@ class VEML6075Sensor : public I2CSensor<> {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/sensors/VL53L1XSensor.h

@@ -80,7 +80,7 @@ class VL53L1XSensor : public I2CSensor<> {
         }
 
         // Descriptive name of the slot # index
-        String slot(unsigned char index) {
+        String description(unsigned char index) {
             return description();
         };
 

code/espurna/settings.cpp

@@ -241,6 +241,22 @@ std::vector<String> settingsKeys() {
     return keys;
 }
 
+
+static std::vector<settings_key_match_t> _settings_matchers;
+
+void settingsRegisterDefaults(const settings_key_match_t& matcher) {
+    _settings_matchers.push_back(matcher);
+}
+
+String settingsQueryDefaults(const String& key) {
+    for (auto& matcher : _settings_matchers) {
+        if (matcher.match(key.c_str())) {
+            return matcher.key(key);
+        }
+    }
+    return String();
+}
+
 // -----------------------------------------------------------------------------
 // Key-value API
 // -----------------------------------------------------------------------------

code/espurna/settings.h

@@ -38,6 +38,17 @@ class settings_key_t {
         settings_key_t(const __FlashStringHelper* value) :
             value(value), index(-1)
         {}
+        settings_key_t() :
+            value(), index(-1)
+        {}
+
+        bool match(const char* _value) const {
+            return (value == _value) || (toString() == _value);
+        }
+
+        bool match(const String& _value) const {
+            return (value == _value) || (toString() == _value);
+        }
 
         String toString() const;
 
@@ -105,19 +116,38 @@ unsigned short convert(const String& value);
 template <>
 unsigned char convert(const String& value);
 
+template<typename T>
+String serialize(const T& value);
+
+template<typename T>
+String serialize(const T& value) {
+    return String(value);
+}
+
 } // namespace settings::internal
 } // namespace settings
 
 // --------------------------------------------------------------------------
 
+struct settings_key_match_t {
+    using match_f = bool(*)(const char* key);
+    using key_f = const String(*)(const String& key);
+
+    match_f match;
+    key_f key;
+};
+
+void settingsRegisterDefaults(const settings_key_match_t& matcher);
+String settingsQueryDefaults(const String& key);
+
+// --------------------------------------------------------------------------
+
 void moveSetting(const String& from, const String& to);
 void moveSetting(const String& from, const String& to, unsigned int index);
 void moveSettings(const String& from, const String& to);
 
-#if 1
 template<typename R, settings::internal::convert_t<R> Rfunc = settings::internal::convert>
 R getSetting(const settings_key_t& key, R defaultValue) __attribute__((noinline));
-#endif
 
 template<typename R, settings::internal::convert_t<R> Rfunc = settings::internal::convert>
 R getSetting(const settings_key_t& key, R defaultValue) {

code/espurna/terminal.cpp

@@ -254,7 +254,12 @@ void _terminalInitCommand() {
             String key = String(e->argv[i]);
             String value;
             if (!Embedis::get(key, value)) {
-                DEBUG_MSG_P(PSTR("> %s =>\n"), key.c_str());
+                const auto maybeDefault = settingsQueryDefaults(key);
+                if (maybeDefault.length()) {
+                    DEBUG_MSG_P(PSTR("> %s => %s (default)\n"), key.c_str(), maybeDefault.c_str());
+                } else {
+                    DEBUG_MSG_P(PSTR("> %s =>\n"), key.c_str());
+                }
                 continue;
             }
 

code/espurna/thingspeak.cpp

@@ -404,7 +404,7 @@ void _tspkFlush() {
     // POST data if any
     if (_tspk_data.length()) {
         _tspk_data.concat("&api_key=");
-        _tspk_data.concat(getSetting<String>("tspkKey", THINGSPEAK_APIKEY));
+        _tspk_data.concat(getSetting("tspkKey", THINGSPEAK_APIKEY));
         --_tspk_tries;
         _tspkPost(getSetting("tspkAddress", THINGSPEAK_ADDRESS));
     }

code/espurna/wifi.cpp

@@ -25,6 +25,7 @@ unsigned long _wifi_gratuitous_arp_last = 0;
 // -----------------------------------------------------------------------------
 // PRIVATE
 // -----------------------------------------------------------------------------
+
 struct wifi_scan_info_t {
     String ssid_scan;
     int32_t rssi_scan;
@@ -58,7 +59,11 @@ void _wifiCheckAP() {
     }
 }
 
-WiFiSleepType_t _wifiSleepModeConvert(const String& value) {
+namespace settings {
+namespace internal {
+
+template<>
+WiFiSleepType_t convert(const String& value) {
     switch (value.toInt()) {
         case 2:
             return WIFI_MODEM_SLEEP;
@@ -70,6 +75,9 @@ WiFiSleepType_t _wifiSleepModeConvert(const String& value) {
     }
 }
 
+}
+}
+
 void _wifiConfigure() {
 
     jw.setHostname(getSetting("hostname").c_str());
@@ -131,7 +139,7 @@ void _wifiConfigure() {
 
     jw.enableScan(getSetting("wifiScan", 1 == WIFI_SCAN_NETWORKS));
 
-    const auto sleep_mode = getSetting<WiFiSleepType_t, _wifiSleepModeConvert>("wifiSleep", WIFI_SLEEP_MODE);
+    const auto sleep_mode = getSetting("wifiSleep", WIFI_SLEEP_MODE);
     WiFi.setSleepMode(sleep_mode);
 
     #if WIFI_GRATUITOUS_ARP_SUPPORT