Generic SML based power meters support (#146)

* add support for energy & power readings on SML based power meters, taking OBIS 16.7.1 for power (using mod. SML Parser lib. by olliiiver)

* switched SML read to use software serial

* made total power meter response controled by meter source to obtain either the sum of phase powers or explicit total power provided by meter

* made mqtt subscriptions to power meter topics meter source dependend

* simplified SML read loop and OBIS handler registration, + minor refactoring

* minor cleanup/style changes and optim. PowerMeter

* fixed build, add SOURCE_SML == 4

* removed optional usage of HW serial for SML power meter

* switched to usage of _powerMeter1Power for SML power reading to allign better with existing code

---------

Co-authored-by: helgeerbe <helge@erbehome.de>

include/PowerMeter.h

@@ -7,6 +7,7 @@
 #include <Hoymiles.h>
 #include <memory>
 #include "SDM.h"
+#include "sml.h"
 
 #ifndef SDM_RX_PIN
 #define SDM_RX_PIN 13
@@ -16,13 +17,24 @@
 #define SDM_TX_PIN 32
 #endif
 
+#ifndef SML_RX_PIN
+#define SML_RX_PIN 35
+#endif
+
+typedef struct {
+  const unsigned char OBIS[6];
+  void (*Fn)(double&);
+  float* Arg;
+} OBISHandler;
+
 class PowerMeterClass {
 public:
     enum SOURCE {
         SOURCE_MQTT = 0,
         SOURCE_SDM1PH = 1,
         SOURCE_SDM3PH = 2,
         SOURCE_HTTP = 3,
+        SOURCE_SML = 4
     };
     void init();
     void mqtt();
@@ -40,14 +52,20 @@ class PowerMeterClass {
     float _powerMeter1Power = 0.0;
     float _powerMeter2Power = 0.0;
     float _powerMeter3Power = 0.0;
-    float _powerMeterTotalPower = 0.0;
     float _powerMeter1Voltage = 0.0;
     float _powerMeter2Voltage = 0.0;
     float _powerMeter3Voltage = 0.0;
-    float _PowerMeterImport = 0.0;
-    float _PowerMeterExport = 0.0;
+    float _powerMeterImport = 0.0;
+    float _powerMeterExport = 0.0;
 
     bool mqttInitDone = false;
+
+    bool smlReadLoop();
+    const std::list<OBISHandler> smlHandlerList{
+        {{0x01, 0x00, 0x10, 0x07, 0x00, 0xff}, &smlOBISW, &_powerMeter1Power},
+        {{0x01, 0x00, 0x01, 0x08, 0x00, 0xff}, &smlOBISWh, &_powerMeterImport},
+        {{0x01, 0x00, 0x02, 0x08, 0x00, 0xff}, &smlOBISWh, &_powerMeterExport}
+    };
 };
 
 extern PowerMeterClass PowerMeter;