From 5757e93b57d58a64df202849397f03127763ee30 Mon Sep 17 00:00:00 2001
From: Siwat Sirichai <siwat@siwatinc.com>
Date: Fri, 13 Oct 2023 22:57:19 +0700
Subject: [PATCH 1/2] initial energy monitoring implementation

---
 src/espmega_iot_emon.cpp | 39 +++++++++++++++++++++++++++++++++++++++
 src/espmega_iot_emon.hpp | 18 ++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 src/espmega_iot_emon.cpp
 create mode 100644 src/espmega_iot_emon.hpp

diff --git a/src/espmega_iot_emon.cpp b/src/espmega_iot_emon.cpp
new file mode 100644
index 0000000..2cb6054
--- /dev/null
+++ b/src/espmega_iot_emon.cpp
@@ -0,0 +1,39 @@
+#include "espmega_iot_emon.hpp"
+
+ESPMega_CT::ESPMega_CT(uint8_t analog_pin, float (*adc_to_watts)(uint16_t adc_value), uint32_t fram_address)
+{
+    this->analog_pin = analog_pin;
+    this->adc_to_watts = adc_to_watts;
+    this->fram_address = fram_address;
+}
+
+void ESPMega_CT::begin()
+{
+    this->last_conversion_timestamp = millis();
+    ESPMega_FRAM.read(fram_address, (uint8_t *)&this->energy, 16);
+    this->power = adc_to_watts(ESPMega_analogRead(this->analog_pin));
+}
+
+void ESPMega_CT::loop()
+{
+    this->energy += (millis() - this->last_conversion_timestamp) / 3600000 * this->power;
+    this->power = adc_to_watts(ESPMega_analogRead(this->analog_pin));
+    this->last_conversion_timestamp = millis();
+    ESPMega_FRAM.write(fram_address, (uint8_t *)&this->energy, 16);
+}
+
+void ESPMega_CT::reset_energy()
+{
+    this->energy = 0;
+    ESPMega_FRAM.write16(fram_address, 0);
+}
+
+long double ESPMega_CT::get_energy()
+{
+    return this->energy;
+}
+
+float ESPMega_CT::get_power()
+{
+    return this->power;
+}
\ No newline at end of file
diff --git a/src/espmega_iot_emon.hpp b/src/espmega_iot_emon.hpp
new file mode 100644
index 0000000..e4993b8
--- /dev/null
+++ b/src/espmega_iot_emon.hpp
@@ -0,0 +1,18 @@
+#pragma once
+#include <ESPMegaPRO.h>
+class ESPMega_CT {
+    public:
+        ESPMega_CT(uint8_t analog_pin,float(*adc_to_watts)(uint16_t adc_value), uint32_t fram_address);
+        void begin();
+        void loop();
+        float get_power();
+        long double get_energy();
+        void reset_energy();
+    private:
+        uint8_t analog_pin;
+        uint32_t fram_address;
+        unsigned long last_conversion_timestamp;
+        float power;
+        long double energy;
+        float (*adc_to_watts)(uint16_t adc_value);
+};
\ No newline at end of file

From 10b55e5aa575154f9946e2e0805b444aba36c21f Mon Sep 17 00:00:00 2001
From: Siwat Sirichai <siwat@siwatinc.com>
Date: Fri, 13 Oct 2023 23:10:41 +0700
Subject: [PATCH 2/2] build in adc reference table

---
 src/espmega_iot_emon.cpp | 16 +++++++++++++++-
 src/espmega_iot_emon.hpp |  1 +
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/espmega_iot_emon.cpp b/src/espmega_iot_emon.cpp
index 2cb6054..863de9f 100644
--- a/src/espmega_iot_emon.cpp
+++ b/src/espmega_iot_emon.cpp
@@ -3,8 +3,8 @@
 ESPMega_CT::ESPMega_CT(uint8_t analog_pin, float (*adc_to_watts)(uint16_t adc_value), uint32_t fram_address)
 {
     this->analog_pin = analog_pin;
-    this->adc_to_watts = adc_to_watts;
     this->fram_address = fram_address;
+    this->adc_to_watts = adc_to_watts;
 }
 
 void ESPMega_CT::begin()
@@ -36,4 +36,18 @@ long double ESPMega_CT::get_energy()
 float ESPMega_CT::get_power()
 {
     return this->power;
+}
+
+float ESPMega_CT::adc_to_watts_builtin(uint16_t adc_value)
+{
+    const float RATIO = 0.1;
+    const float BURDEN_RESISTANCE = 20;
+    const float VOLTAGE = 220;
+    const uint16_t ADC_RANGE_START = 500;
+    const uint16_t ADC_RANGE_END = 16000;
+    const float ADC_RANGE = 12;
+    float burden_voltage = (adc_value - ADC_RANGE_START) / (ADC_RANGE_END - ADC_RANGE_START) * ADC_RANGE;
+    float secondary_current = burden_voltage / BURDEN_RESISTANCE;
+    float primary_current = secondary_current / RATIO;
+    return primary_current * VOLTAGE;
 }
\ No newline at end of file
diff --git a/src/espmega_iot_emon.hpp b/src/espmega_iot_emon.hpp
index e4993b8..818ce36 100644
--- a/src/espmega_iot_emon.hpp
+++ b/src/espmega_iot_emon.hpp
@@ -15,4 +15,5 @@ class ESPMega_CT {
         float power;
         long double energy;
         float (*adc_to_watts)(uint16_t adc_value);
+        float adc_to_watts_builtin(uint16_t adc_value);
 };
\ No newline at end of file