+--------------------------------------------------------------+
|                Repurposed Commercial Smart Plug              |
|                                                              |
|  +---------------------+        +-------------------------+  |
|  | BL0937 Shunt &      | -----> | ESP32-C3 Pulse Counter  |  |
|  | High-Voltage Divider|        | & Frequency Analyzer    |  |
|  +---------------------+        +-------------------------+  |
|                                              |               |
|                                              v               |
|  +--------------------------------------------------------+  |
|  | ESPHome Native API Client (Home Assistant Integration) |  |
|  +--------------------------------------------------------+  |
|                                              |               |
|                                              v               |
|  +---------------------+        +-------------------------+  |
|  | 16A Latching Relay  |        | Status Bi-Color LED &   |  |
|  | Control Driver      |        | Physical Override Button|  |
|  +---------------------+        +-------------------------+  |
+--------------------------------------------------------------+

[ESP32-C3 Controller]                              [BL0937 Energy Meter IC]
+--------------------+                            +------------------------+
|              GPIO4 |<---------------------------| CF (Power Pulse)       |
|              GPIO5 |<---------------------------| CF1 (V / I Pulse)      |
|              GPIO6 |--------------------------->| SEL (V/I Mode Select)  |
|                    |                            +------------------------+
|             GPIO12 |---------------------------> [16A Relay Transistor]
|              GPIO3 |<--------------------------- [Pushbutton Switch]
|              GPIO7 |---------------------------> [Bi-Color Status LED]
|                    |
|               3.3V |---------------------------> 3.3V Non-Isolated Rail
|                GND |---------------------------> Common High-Voltage Neutral
+--------------------+

/*
* Repurposed Tuya Smart Plug Power Monitoring via ESPHome
* Target: ESP32-C3 + BL0937 Shunt + 16A Relay
*/
#include <Arduino.h>
#define RELAY_PIN       12
#define BUTTON_PIN      3
#define BL0937_CF_PIN   4  // Power pulse
#define BL0937_CF1_PIN  5  // Voltage/Current pulse
#define BL0937_SEL_PIN  6  // Select: HIGH=Voltage, LOW=Current
volatile uint32_t cf_pulse_count = 0;
volatile uint32_t cf1_pulse_count = 0;
void IRAM_ATTR cf_isr() {
cf_pulse_count++;
}
void IRAM_ATTR cf1_isr() {
cf1_pulse_count++;
}
void setup() {
Serial.begin(115200);
pinMode(RELAY_PIN, OUTPUT);
digitalWrite(RELAY_PIN, HIGH); // Turn relay ON
pinMode(BUTTON_PIN, INPUT_PULLUP);
pinMode(BL0937_SEL_PIN, OUTPUT);
digitalWrite(BL0937_SEL_PIN, HIGH); // Select Voltage mode
pinMode(BL0937_CF_PIN, INPUT);
pinMode(BL0937_CF1_PIN, INPUT);
attachInterrupt(digitalPinToInterrupt(BL0937_CF_PIN), cf_isr, RISING);
attachInterrupt(digitalPinToInterrupt(BL0937_CF1_PIN), cf1_isr, RISING);
Serial.println("Repurposed Smart Plug Energy Monitor Ready.");
}
void loop() {
static unsigned long last_calc = 0;
if (millis() - last_calc >= 2000) {
last_calc = millis();
// Read pulse counts and calculate rough electrical parameters
float power_w = (float)cf_pulse_count * 1.15f;
float voltage_v = 220.0f + ((float)cf1_pulse_count * 0.05f);
cf_pulse_count = 0;
cf1_pulse_count = 0;
Serial.printf("[Power Meter] Active Power: %.1f W | Mains Voltage: %.1f V
", power_w, voltage_v);
}
// Handle local physical button toggle
if (digitalRead(BUTTON_PIN) == LOW) {
digitalWrite(RELAY_PIN, !digitalRead(RELAY_PIN));
delay(300); // Debounce
}
}