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

🔌 Pin Connections

ESP32 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
Modbus RTU
RS485 Module	GPIO17	TX	UART TX
RS485 Module	GPIO16	RX	UART RX
RS485 Module	3.3V	VCC	Power
RS485 Module	GND	GND	Ground
I2C OLED Display
OLED SDA	GPIO21	SDA	I2C Data
OLED SCL	GPIO22	SCL	I2C Clock
OLED VCC	3.3V	VCC	Power
OLED GND	GND	GND	Ground

🔌 Detailed Wiring Guide

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:
     ┌─────────┐
     │  Power  │ ← AC Power (L/N)
     │ Current │ ← CT Clamp connections
     │   A+    │ ← RS485 Data+
     │   B-    │ ← RS485 Data-
     │   GND   │ ← Optional ground
     └─────────┘

Step 2: I2C OLED Display Setup

OLED Display Connections

SSD1306 128x64 OLED:
     ┌─────────┐
     │   VCC   │ ← 3.3V (ESP32)
     │   GND   │ ← GND (ESP32)
     │   SDA   │ ← GPIO21 (ESP32 SDA)
     │   SCL   │ ← GPIO22 (ESP32 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 Modbus: Connect A+ and B- wires to RS485 module
3. Wire Power: Connect AC power wires to meter (if required)
4. Wire Current: Connect current transformers (if used)

🏗️ Enclosure Recommendations

3D Printed Enclosure

• Material: ABS or PLA
• Dimensions: Minimum 100mm x 60mm x 30mm
• Features Needed:
  • Ventilation holes for heat dissipation
  • Cutouts for OLED display
  • Access holes for wiring
  • Mounting holes for PCB

Commercial Enclosure

• Type: IP65 rated plastic or metal enclosure
• Size: DIN rail mount or wall mount
• Features:
  • Clear window for OLED display
  • Cable entry glands
  • Grounding lug

📏 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 USB cable: Ensure data cable (not charge-only)
• Check voltage: Verify 3.3V and 5V rails
• Check connections: Verify all power connections

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
• Enclosure (if used) is properly assembled
• Safety measures are in place

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