esp32-energy-meter/docs/hardware-setup.md

Hardware Setup Guide

⚠️ Safety Warning

⚠️ HIGH VOLTAGE: This project involves working with mains electricity. Always disconnect power before making connections and use appropriate safety measures. The authors are not responsible for any damage or injury resulting from the use of this project.

📋 Required Components

Core Hardware

Component	Specification	Quantity	Notes
ESP32 Board	Any ESP32 variant	1	DevKit, WROOM, etc.
Energy Meter	JSY with Modbus RTU	1	Main measurement device
OLED Display	SSD1306 128x64 I2C	1	For local display
RS485 Module	TTL to RS485 converter	1	For Modbus communication
Power Supply	3.3V/5V	1	USB power recommended

Optional Components

Component	Purpose	Notes
3D Printed Enclosure	Protection	Recommended for permanent installation
Current Clamps	Non-invasive measurement	For measuring current without direct connection
Voltage Transformers	Voltage isolation	If voltage measurement is required

🏭 Original Author's Recommended Hardware

The following specific components were tested and recommended by Giovanni Aggiustatutto in the original project:

Recommended Hardware List

Component	Model/Specification	Source	Purpose
Energy Meter	JSY-MK-194G	AliExpress	Main measurement device with Modbus RTU
ESP32 Board	ESP32 Wemos D1 Mini	General ESP32 supplier	Main controller board
Power Supply	Meanwell APV-8-5 5V 8W	Electronics supplier	5V power supply for the system
OLED Display	SSD1306 I2C 0.96"	General electronics supplier	Local display for readings

Hardware Details

JSY-MK-194G Energy Meter

• Protocol: Modbus RTU over RS485
• Channels: Dual channel measurement capability
• Accuracy: High precision power monitoring
• Communication: RS485 interface for reliable data transmission
• Features: Voltage, current, power, energy, and frequency measurement

ESP32 Wemos D1 Mini

• Board Type: Compact ESP32 development board
• Pins: Suitable for I2C and UART communication
• WiFi: Built-in WiFi for Home Assistant connectivity
• Memory: Sufficient for ESPHome firmware and display operations

Meanwell APV-8-5 Power Supply

• Output: 5V DC, 8W maximum power
• Efficiency: High efficiency switching power supply
• Protection: Over voltage and over current protection
• Reliability: Industrial-grade power supply for continuous operation

SSD1306 0.96" OLED Display

• Resolution: 128x64 pixels
• Interface: I2C communication
• Size: Compact 0.96" display suitable for enclosure mounting
• Visibility: High contrast OLED for clear reading visibility

Why These Components?

These specific components were chosen by the original author because they:

• Provide reliable performance in energy monitoring applications
• Are readily available from common electronics suppliers
• Work seamlessly together with the ESPHome firmware
• Offer good value for the performance provided
• Have community support and documentation available

Alternative Options

While these specific components are recommended, the project is compatible with:

• Other JSY energy meter models with Modbus RTU capability
• Various ESP32 development boards (DevKit, NodeMCU, etc.)
• Different 5V power supplies with adequate current capacity
• Other SSD1306 OLED displays in various sizes

🔌 Pin Connections

ESP32 Wemos D1 Mini Pinout (Recommended)

ESP32 Wemos D1 Mini Pin Layout:
         ┌─────────┐
     3V3 │ RST   A0 │
      D0 │ D1    D2 │
      D3 │ GND   D4 │
      5V │ 3V3   GND │
         └─────────┘

GPIO Pin Mapping (Recommended for this project):
D0  = GPIO16 ← RX for Modbus
D1  = GPIO22 ← I2C SCL  
D2  = GPIO21 ← I2C SDA
D3  = GPIO0  (Boot select - don't use)
D4  = GPIO2  (Status LED - built-in)
D5  = GPIO14 (Available for expansion)
D6  = GPIO12 (Available for expansion)  
D7  = GPIO13 (Available for expansion)
D8  = GPIO15 (Available for expansion)
A0  = ADC0   (Available for analog sensors)

Note: Pin labels on D1 Mini correspond to specific GPIO numbers

Alternative ESP32 DevKit V1 Pinout:

ESP32 DevKit V1 Pin Layout:
         ┌─────────┐
    3V3  │1       38│ GND
     EN  │2       37│ GPIO0
   SENSOR │3       36│ GPIO2
   VP/GPIO36 │4       35│ GPIO4
   VN/GPIO39 │5       34│ GPIO16 ← RX for Modbus
   GPIO34 │6       33│ GPIO17 ← TX for Modbus
   GPIO35 │7       32│ GPIO5
   GPIO32 │8       31│ GPIO18 ← I2C SCL
   GPIO33 │9       30│ GPIO19 ← I2C SDA
    5V   │10      29│ GPIO21
    GND  │11      28│ GND
    GND  │12      27│ GPIO3 (RX0)
    GPIO25│13      26│ GPIO1 (TX0)
   GPIO26│14      25│ GPIO22 ← SCL (Alt)
   GPIO27│15      24│ GPIO23 ← SDA (Alt)
         └─────────┘

Connection Table

Component	ESP32 Pin	Signal	Notes
Power Supply
5V Power Supply (+)	+5V	VCC	Main ESP32 power
5V Power Supply (-)	GND	GND	Power ground
Energy Meter Power
JSY Meter VCC	3.3V	VCC	Energy meter power
JSY Meter GND	GND	GND	Energy meter ground
Modbus RTU Communication
RS485 Module TX	GPIO16	RX	Modbus RX (Pin 16)
RS485 Module RX	GPIO17	TX	Modbus TX (Pin 17)
RS485 Module VCC	3.3V	VCC	Module power
RS485 Module GND	GND	GND	Module ground
I2C OLED Display
OLED SDA	GPIO21	SDA	I2C Data (Pin 21)
OLED SCL	GPIO22	SCL	I2C Clock (Pin 22)
OLED VCC	3.3V	VCC	Display power
OLED GND	GND	GND	Display ground

🔌 Detailed Wiring Guide

Step 0: Power Supply Setup (Critical)

Power Distribution Overview

The original author's design uses a centralized power distribution approach:

Mains AC (L/N) 
    ↓
5V Power Supply (Meanwell APV-8-5)
    ↓
ESP32 +5V pin (main power)
    ↓
ESP32 3.3V pin (internal regulator)
    ↓
Energy Meter VCC, OLED VCC, RS485 Module VCC

5V Power Supply Connections

5V Power Supply (Meanwell APV-8-5):
     ┌─────────┐
     │    +    │ ← Mains Line (L)
     │    -    │ ← Mains Neutral (N)
     │   5V+   │ ← ESP32 +5V pin
     │   GND   │ ← ESP32 GND pin
     └─────────┘

ESP32 Power Distribution

ESP32 Power Rails:
+5V pin  → Powers ESP32 main circuit
3.3V pin → Powers external devices:
           • JSY Energy Meter VCC
           • OLED Display VCC  
           • RS485 Module VCC
GND pin  → Common ground for all devices

Step 1: RS485 Modbus Setup

RS485 Module Connections

RS485 Module Pinout:
     ┌─────────┐
     │   VCC   │ ← 3.3V (ESP32)
     │   GND   │ ← GND (ESP32)
     │   RE/DE │ ← Not connected (automatic)
     │    RE   │ ← Not connected
     │    DE   │ ← Not connected
     │    DI   │ ← GPIO17 (ESP32 TX)
     │   RO/RX │ ← GPIO16 (ESP32 RX)
     └─────────┘
     │   A+    │ ← JSY Meter A+ (or Data+)
     │   B-    │ ← JSY Meter B- (or Data-)
     │   GND   │ ← Optional: Earth ground
     └─────────┘

JSY Energy Meter Connections

JSY Energy Meter:
     ┌─────────┐
     │   VCC   │ ← ESP32 3.3V pin
     │   GND   │ ← ESP32 GND pin
     │    L    │ ← Mains Line (AC Power)
     │    N    │ ← Mains Neutral (AC Power)
     │   A+    │ ← RS485 Data+
     │   B-    │ ← RS485 Data-
     │   CT1   │ ← Current Transformer 1
     │   CT2   │ ← Current Transformer 2
     └─────────┘

Note: The energy meter receives its operating power (VCC/GND) from the ESP32's 3.3V rail, while the mains power (L/N) is for measurement purposes only.

Step 2: I2C OLED Display Setup

OLED Display Connections

SSD1306 128x64 OLED:
     ┌─────────┐
     │   VCC   │ ← 3.3V (ESP32)
     │   GND   │ ← GND (ESP32)
     │   SDA   │ ← GPIO21 (D2) ← I2C SDA
     │   SCL   │ ← GPIO22 (D1) ← I2C SCL
     └─────────┘

I2C Address Configuration

The default I2C address for SSD1306 is 0x3C. If you have multiple I2C devices, you may need to use 0x3D by connecting the address pin to VCC.

🔧 Hardware Assembly Steps

Step 1: Prepare the ESP32

1. Verify ESP32: Check that your ESP32 board is working properly
2. Install Headers: Solder pin headers if not pre-installed
3. Test Power: Connect to USB and verify power-on LED

Step 2: Install RS485 Module

1. Position Module: Place RS485 module on breadboard or PCB
2. Connect Power: Wire 3.3V and GND to ESP32
3. Connect UART: Wire TX/RX pins as shown in table above
4. Connect to Meter: Wire A+ and B- to JSY energy meter

Step 3: Install OLED Display

1. Position Display: Mount OLED in visible location
2. Wire I2C: Connect SDA, SCL, VCC, and GND
3. Test Communication: Verify I2C detection (see troubleshooting)

Step 4: Connect Energy Meter

1. Power Off: Ensure all power is disconnected
2. Wire Power: Connect VCC to ESP32 3.3V, GND to ESP32 GND
3. Wire Modbus: Connect A+ and B- wires to RS485 module
4. Wire Mains: Connect L and N for measurement (high voltage!)
5. Wire Current: Connect current transformers (if used)

Step 5: Final Power Distribution Verification

Complete Power Chain (as per original author design):

Mains AC (120V/230V)
    ↓
5V Power Supply (+5V, GND)
    ↓
ESP32 Wemos D1 Mini (+5V, GND pins)
    ↓
ESP32 Internal 3.3V Regulator
    ↓
ESP32 3.3V pin supplies:
    ├── JSY Energy Meter (VCC, GND)
    ├── SSD1306 OLED Display (VCC, GND)
    └── RS485 Module (VCC, GND)

📏 Calibration and Testing

Initial Power-On

1. Connect Power: Apply power to ESP32 via USB
2. Check Serial: Monitor serial output for boot messages
3. Verify WiFi: Check WiFi connection status
4. Test Display: Verify OLED shows "Energy Meter" title

Modbus Communication Test

1. Check Logs: Look for "JSY energy meter protocol" messages
2. Verify Address: Ensure meter address is 0x1 (default)
3. Monitor Communication: Watch for read errors or timeouts

Sensor Validation

1. Check Values: Verify all sensors show reasonable readings
2. Verify Display: Confirm power, voltage, current display correctly
3. Test WiFi Icon: Verify WiFi status indicator functionality

🔍 Troubleshooting Hardware Issues

Common Problems

No Power to ESP32

• Check 5V power supply: Verify mains connection and 5V output
• Check power supply polarity: Ensure +5V to ESP32 +5V pin, GND to GND
• Check ESP32 3.3V: Verify internal regulator is working (should power peripherals)
• Check connections: Verify all power connections match the original design

OLED Not Displaying

• Check I2C address: Default should be 0x3C
• Check wiring: Verify SDA/SCL connections
• Check library: Ensure SSD1306 library is loaded

Modbus Communication Failure

• Check RS485 wiring: Verify A+ and B- connections
• Check address: Ensure meter address matches configuration
• Check termination: Add 120Ω termination if long cables
• Check power: Verify meter is powered

Intermittent Readings

• Check power supply: Ensure stable power to all components
• Check connections: Verify all wire connections are secure
• Check EMI: Move away from high-voltage areas
• Add filtering: Use ferrite beads on power lines

Diagnostic Tools

• Serial Monitor: Monitor ESP32 serial output
• I2C Scanner: Use I2C scan to find devices
• Oscilloscope: Check RS485 signal quality
• Multimeter: Verify voltage levels and continuity

📋 Final Checklist

Before proceeding to software configuration:

• ESP32 powers on and boots successfully
• OLED display shows "Energy Meter" title
• WiFi connection established
• Modbus communication working
• Energy meter readings are stable
• All connections are secure
• Safety measures are in place

Once hardware is verified, proceed to the Configuration Guide for ESPHome setup.