feat(firmware): IM1281C driver

hardware/firmware/lib/IM1281C/src/IM1281C.h

@@ -0,0 +1,65 @@
+#ifndef HELIOS_IM1281C_H
+#define HELIOS_IM1281C_H
+
+#include <Arduino.h>
+#include <ModbusMaster.h>
+
+struct IM1281CAData
+{
+  float voltage = 0.0f;
+  float current = 0.0f;
+  float power = 0.0f;
+  float energy = 0.0f;
+  float powerFactor = 0.0f;
+  float co2 = 0.0f;
+  float temperature = 0.0f;
+  float frequency = 0.0f;
+  bool valid = false;
+};
+
+struct IM1281CBData
+{
+  float voltage = 0.0f;
+  float current = 0.0f;
+  float power = 0.0f;
+  float energy = 0.0f;
+  float powerFactor = 0.0f;
+  float co2 = 0.0f;
+  bool valid = false;
+};
+
+class IM1281C
+{
+public:
+  IM1281C();
+
+  bool begin(HardwareSerial &serial,
+             int8_t rxPin,
+             int8_t txPin,
+             uint8_t slaveAddress = 1,
+             uint32_t baudRate = 4800,
+             uint32_t serialConfig = SERIAL_8N1);
+
+  bool readA();
+  bool readB();
+  bool readAll();
+
+  const IM1281CAData &a() const;
+  const IM1281CBData &b() const;
+  uint8_t lastAResult() const;
+  uint8_t lastBResult() const;
+
+private:
+  static uint32_t combineWords(uint16_t highWord, uint16_t lowWord);
+  static float scaleValue(uint32_t raw, float scale);
+
+  ModbusMaster _node;
+  HardwareSerial *_serial;
+  uint8_t _slaveAddress;
+  uint8_t _lastAResult;
+  uint8_t _lastBResult;
+  IM1281CAData _a;
+  IM1281CBData _b;
+};
+
+#endif // HELIOS_IM1281C_H