Add MPOD files

mpod.cpp

+#include "mpod.hpp"
+#include <SNMP.h>
+#include <WiFiUdp.h>
+
+MPOD::MPOD() {
+    bool _on = false;
+    bool _up = false;
+    bool _down = false;
+    float _measurementSenseVoltage = 0;
+    float _measurementCurrent = 0;
+    float _voltage = 0;
+    float _current = 0;
+    float _voltageRiseRate = 0;
+}
+
+
+// Create an SNMP SETREQUEST message to setup MPOD
+SNMP::Message* MPOD::setup() {
+    // Use read/write community, not read-only
+    SNMP::Message* message = new SNMP::Message(SNMP::VERSION2C, "guru", SNMP::TYPE_SETREQUEST);
+    // In SETREQUEST, use node type and set the value.
+    // OUTPUT SWITCH, integer type, 0 is OFF and 1 is ON.
+    message->add(OID::NAMES[OID::OUTPUTSWITCH], new IntegerBER(0));
+    // OUTPUT VOLTAGE is an opaque float embedded in an opaque node
+    message->add(OID::NAMES[OID::OUTPUTVOLTAGE], new OpaqueBER(new OpaqueFloatBER(10.0)));
+    // OUTPUT CURRENT is an opaque float embedded in an opaque node
+    message->add(OID::NAMES[OID::OUTPUTCURRENT], new OpaqueBER(new OpaqueFloatBER(0.001)));
+    // OUTPUT VOLTAGE RISE RATE is negative. Don't ask me why...
+    message->add(OID::NAMES[OID::OUTPUTVOLTAGERISERATE], new OpaqueBER(new OpaqueFloatBER(-1.0)));
+    return message;
+}
+
+    // Create an SNMP GETREQUEST message
+SNMP::Message* MPOD::read() {
+    SNMP::Message* message = new SNMP::Message(SNMP::VERSION2C, "public", SNMP::TYPE_GETREQUEST);
+    // In GETREQUEST, values are always of type NULL.
+    message->add(OID::NAMES[OID::OUTPUTSTATUS]);
+    message->add(OID::NAMES[OID::OUTPUTMEASUREMENTSENSEVOLTAGE]);
+    message->add(OID::NAMES[OID::OUTPUTMEASUREMENTCURRENT]);
+    return message;
+}
+
+    // Create an SNMP SETREQUEST message to switch on or off the MPOD
+SNMP::Message* MPOD::output(const bool on) {
+    SNMP::Message* message = new SNMP::Message(SNMP::VERSION2C, "guru", SNMP::TYPE_SETREQUEST);
+    // In SETREQUEST, use node type and set the value.
+    // OUTPUT SWITCH, integer type, 0 is OFF and 1 is ON.
+    message->add(OID::NAMES[OID::OUTPUTSWITCH], new IntegerBER(on ? 1 : 0));
+    return message;
+}
+
+    // Parse incoming message
+bool MPOD::message(const SNMP::Message *message) {
+    unsigned int found = 0;
+    unsigned int index = 0;
+    // Get the variable binding list from the message.
+    VarBindList *varbindlist = message->getVarBindList();
+    for (unsigned int index = 0; index < varbindlist->count(); ++index) {
+        // Each variable binding is a sequence of 2 objects:
+        // - First one is and ObjectIdentifierBER. It holds the OID
+        // - Second is the value of any type
+        VarBind *varbind = (*varbindlist)[index];
+        // There is a convenient function to get the OID as a const char*
+        const char *name = varbind->getName();
+        switch (OID::match(name)) {
+        case OID::OUTPUTSTATUS: {
+            // OUTPUTSTATUS is defined in MIB as BITS but encoded as OCTETSTRING by MPOD
+            OctetStringBER *status = static_cast<OctetStringBER*>(varbind->getValue());
+            _on = status->getBit(0);
+            _up = status->getBit(11);
+            _down = status->getBit(12);
+        }
+            found++;
+            break;
+        case OID::OUTPUTMEASUREMENTSENSEVOLTAGE:
+            // Use private helper function to extract float value
+            _measurementSenseVoltage = getFloatFromVarBind(varbind);
+            found++;
+            break;
+        case OID::OUTPUTMEASUREMENTCURRENT:
+            _measurementCurrent = getFloatFromVarBind(varbind);
+            found++;
+            break;
+        case OID::OUTPUTSWITCH:
+            // Use private helper function to extract integer value
+            _on = getIntegerFromVarBind(varbind);
+            found++;
+            break;
+        case OID::OUTPUTVOLTAGE:
+            _voltage = getFloatFromVarBind(varbind);
+            found++;
+            break;
+        case OID::OUTPUTCURRENT:
+            _current = getFloatFromVarBind(varbind);
+            found++;
+            break;
+        case OID::OUTPUTVOLTAGERISERATE:
+            _voltageRiseRate = getFloatFromVarBind(varbind);
+            found++;
+            break;
+        }
+    }
+    // Return true if nodes found, that means this is a valid response from MPOD
+    return found;
+}
+
+bool MPOD::isOn() const {
+    return _on;
+}
+
+bool MPOD::isUp() const {
+    return _up;
+}
+
+bool MPOD::isDown() const {
+    return _down;
+}
+
+float MPOD::getMeasurementSenseVoltage() const {
+    return _measurementSenseVoltage;
+}
+
+float MPOD::getMeasurementCurrent() const {
+    return _measurementCurrent;
+}
+
+float MPOD::getVoltage() const {
+    return _voltage;
+}
+
+float MPOD::getCurrent() const {
+    return _current;
+}
+
+float MPOD::getVoltageRiseRate() const {
+    return _voltageRiseRate;
+}
+
+// Use appropriate cast to get integer value
+unsigned int MPOD::getIntegerFromVarBind(const VarBind *varbind) {
+    return static_cast<IntegerBER*>(varbind->getValue())->getValue();
+}
+
+// Use appropriate casts to get embedded opaque float value
+float MPOD::getFloatFromVarBind(const VarBind *varbind) {
+    return static_cast<OpaqueFloatBER*>(static_cast<OpaqueBER*>(varbind->getValue())->getBER())->getValue();
+}
+
+
+WiFiUDP udp;
+SNMP::Manager snmp;
+MPOD mpod;
+
+// Event handler to process SNMP messages
+void onMessage(const SNMP::Message *message, const IPAddress remote, const uint16_t port) {
+    if (mpod.message(message)) {
+        Serial.println();
+        Serial.print("MPOD status");
+        Serial.print(mpod.isOn() ? " on" : " off");
+        if (mpod.isUp()) {
+            Serial.print(" up");
+        }
+        if (mpod.isDown()) {
+            Serial.print(" down");
+        }
+        Serial.println();
+        Serial.print("HV voltage ");
+        Serial.print(mpod.getMeasurementSenseVoltage());
+        Serial.print(" V (");
+        Serial.print(mpod.getVoltage());
+        Serial.print(") current ");
+        Serial.print(mpod.getMeasurementCurrent());
+        Serial.print(" A (");
+        Serial.print(mpod.getCurrent());
+        Serial.print(") rise rate ");
+        Serial.print(mpod.getVoltageRiseRate());
+        Serial.println(" V/s");
+    } else {
+        Serial.println("Received non-MPOD traffic");
+    }
+}
+
+void initializeSNMP() {
+    snmp.begin(&udp);
+    snmp.onMessage(onMessage);
+}

mpod.hpp

+#pragma once
+#include <SNMP.h>
+
+using SNMP::IntegerBER;
+using SNMP::OctetStringBER;
+using SNMP::OpaqueBER;
+using SNMP::OpaqueFloatBER;
+using SNMP::VarBind;
+using SNMP::VarBindList;
+
+
+class MPOD {
+    public:
+        // Simple helper class to handle OIDs
+        class OID {
+        public:
+            enum {
+                OUTPUTSTATUS,
+                OUTPUTMEASUREMENTSENSEVOLTAGE,
+                OUTPUTMEASUREMENTCURRENT,
+                OUTPUTSWITCH,
+                OUTPUTVOLTAGE,
+                OUTPUTCURRENT,
+                OUTPUTVOLTAGERISERATE,
+                UNKNOWN,
+                COUNT = UNKNOWN,
+            };
+    
+            static inline const char *NAMES[] = {
+                    "1.3.6.1.4.1.19947.1.3.2.1.4.1",
+                    "1.3.6.1.4.1.19947.1.3.2.1.5.1",
+                    "1.3.6.1.4.1.19947.1.3.2.1.7.1",
+                    "1.3.6.1.4.1.19947.1.3.2.1.9.1",
+                    "1.3.6.1.4.1.19947.1.3.2.1.10.1",
+                    "1.3.6.1.4.1.19947.1.3.2.1.12.1",
+                    "1.3.6.1.4.1.19947.1.3.2.1.13.1",
+            };
+    
+            // Returns index of OID equals to name
+            // Returns UNKNOWN if none
+            static unsigned int match(const char *name) {
+                for (unsigned int index = 0; index < COUNT; ++index) {
+                    if (strcmp(NAMES[index], name) == 0) {
+                        return index;
+                    }
+                }
+                return UNKNOWN;
+            }
+        };
+    
+        // Create an SNMP SETREQUEST message to setup MPOD
+        MPOD();  
+        SNMP::Message* setup();
+        SNMP::Message* read();
+        SNMP::Message* output(const bool);
+        bool message(const SNMP::Message*);
+        bool isOn() const;
+        bool isUp() const;
+        bool isDown() const;
+        float getMeasurementSenseVoltage() const;
+        float getMeasurementCurrent() const;
+        float getVoltage() const;
+        float getCurrent() const;
+        float getVoltageRiseRate() const;
+    
+    private:
+        unsigned int getIntegerFromVarBind(const VarBind*);
+        float getFloatFromVarBind(const VarBind*);
+        bool _on;
+        bool _up;
+        bool _down;
+        float _measurementSenseVoltage;
+        float _measurementCurrent;
+        float _voltage;
+        float _current;
+        float _voltageRiseRate;
+};
+
+extern SNMP::Manager snmp;
+extern MPOD mpod;
+
+// Event handler to process SNMP messages
+void onSNMPMessage(const SNMP::Message *message, const IPAddress remote, const uint16_t port);
+void initializeSNMP();
+