JK BMS: Support for MQTT

include/BatteryStats.h

@@ -95,4 +95,6 @@ class JkBmsBatteryStats : public BatteryStats {
 
     private:
         JkBms::DataPointContainer _dataPoints;
+        mutable uint32_t _lastMqttPublish = 0;
+        mutable uint32_t _lastFullMqttPublish = 0;
 };

include/JkBmsDataPoints.h

@@ -185,6 +185,10 @@ class DataPoint {
         std::string const& getUnitText() const { return _strUnit; }
         uint32_t getTimestamp() const { return _timestamp; }
 
+        bool operator==(DataPoint const& other) const {
+            return _value == other._value;
+        }
+
     private:
         std::string _strLabel;
         std::string _strValue;

src/BatteryStats.cpp

@@ -1,5 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
+#include <vector>
+#include <algorithm>
 #include "BatteryStats.h"
+#include "Configuration.h"
 #include "MqttSettings.h"
 #include "JkBmsDataPoints.h"
 
@@ -145,6 +148,34 @@ void PylontechBatteryStats::mqttPublish() const
 void JkBmsBatteryStats::mqttPublish() const
 {
     BatteryStats::mqttPublish();
+
+    using Label = JkBms::DataPointLabel;
+
+    static std::vector<Label> mqttSkip = {
+        Label::CellsMilliVolt, // complex data format
+        Label::ModificationPassword, // sensitive data
+        Label::BatterySoCPercent // already published by base class
+    };
+
+    CONFIG_T& config = Configuration.get();
+
+    // publish all topics every minute, unless the retain flag is enabled
+    bool fullPublish = _lastFullMqttPublish + 60 * 1000 < millis();
+    fullPublish &= !config.Mqtt_Retain;
+
+    for (auto iter = _dataPoints.cbegin(); iter != _dataPoints.cend(); ++iter) {
+        // skip data points that did not change since last published
+        if (!fullPublish && iter->second.getTimestamp() < _lastMqttPublish) { continue; }
+
+        auto skipMatch = std::find(mqttSkip.begin(), mqttSkip.end(), iter->first);
+        if (skipMatch != mqttSkip.end()) { continue; }
+
+        String topic((std::string("battery/") + iter->second.getLabelText()).c_str());
+        MqttSettings.publish(topic, iter->second.getValueText().c_str());
+    }
+
+    _lastMqttPublish = millis();
+    if (fullPublish) { _lastFullMqttPublish = _lastMqttPublish; }
 }
 
 void JkBmsBatteryStats::updateFrom(JkBms::DataPointContainer const& dp)

src/JkBmsController.cpp

@@ -312,9 +312,9 @@ void Controller::frameComplete()
             ts, _buffer.size());
         for (size_t ctr = 0; ctr < _buffer.size(); ++ctr) {
             if (ctr % 16 == 0) {
-                MessageOutput.printf("\r\n[%11.3f] JK BMS: ", ts);
+                MessageOutput.printf("\r\n[%11.3f] JK BMS:", ts);
             }
-            MessageOutput.printf("%02x ", _buffer[ctr]);
+            MessageOutput.printf(" %02x", _buffer[ctr]);
         }
         MessageOutput.println();
     }

src/JkBmsDataPoints.cpp

@@ -48,7 +48,14 @@ std::string dataPointValueToStr(tCells const& v) {
 void DataPointContainer::updateFrom(DataPointContainer const& source)
 {
     for (auto iter = source.cbegin(); iter != source.cend(); ++iter) {
-        _dataPoints.erase(iter->first);
+        auto pos = _dataPoints.find(iter->first);
+
+        if (pos != _dataPoints.end()) {
+            // do not update existing data points with the same value
+            if (pos->second == iter->second) { continue; }
+
+            _dataPoints.erase(pos);
+        }
         _dataPoints.insert(*iter);
     }
 }