SGW-01 V1.0

SGW01 SIM7600 Solar Pump Gateway

ESP-IDF based IoT gateway for solar pump monitoring and control using SIM7600 4G modem and Modbus RTU.

Features

• ✅ 4G/LTE Connectivity via SIM7600 modem
• ✅ Modbus RTU Master for solar pump data collection
• ✅ ThingsBoard Integration via MQTT
• ✅ Remote Control via MQTT attributes
• ✅ Real-time Telemetry publishing
• ✅ Configurable via menuconfig

Hardware Requirements

• ESP32-S3 development board
• SIM7600 4G/LTE modem module
• RS485 transceiver (for Modbus)
• Solar pump controller with Modbus RTU interface
• SIM card with data plan

Quick Start

1. Prerequisites

Install ESP-IDF v5.0 or later:

# Follow ESP-IDF installation guide
https://docs.espressif.com/projects/esp-idf/en/latest/esp32/get-started/

2. Configure Project

cd d:\YMH\Myannovation\Projects\SGW01\FW\sgw01_v1.0.0
idf.py menuconfig

Important Configuration:

• ThingsBoard Configuration → Device Access Token (MUST SET!)
• SIM7600 Configuration → APN settings for your carrier
• Modbus Configuration → Slave address and baud rate

3. Build and Flash

idf.py build
idf.py -p COM_PORT flash monitor

Pin Configuration

SIM7600 Connections

Modbus RS485 Connections

Status LED

Configuration Options

SIM7600 Settings

CONFIG_GSM_APN="internet"           # Your carrier's APN
CONFIG_GSM_USER=""                  # APN username (if required)
CONFIG_GSM_PASS=""                  # APN password (if required)

ThingsBoard Settings

CONFIG_TB_BROKER="demo.thingsboard.io"
CONFIG_TB_PORT=1883
CONFIG_TB_TOKEN="YOUR_DEVICE_TOKEN"     # Get from ThingsBoard
CONFIG_TB_CLIENT_ID="ESP32_SGW01"
CONFIG_TB_PUB_TOPIC="v1/devices/me/telemetry"
CONFIG_TB_SUB_TOPIC="v1/devices/me/attributes"

Modbus Settings

CONFIG_MODBUS_SLAVE_ADDR=1          # Solar pump Modbus address
CONFIG_MODBUS_BAUD_RATE=9600        # Modbus baud rate
CONFIG_MODBUS_READ_INTERVAL_MS=100  # Read interval
CONFIG_MQTT_PUBLISH_INTERVAL_MS=200 # Publish interval

Solar Pump Parameters

The gateway monitors 11 parameters from the solar pump:

1. Actual_voltage - Current voltage reading
2. Undervoltage_limit - Low voltage threshold
3. Overvoltage_limit - High voltage threshold
4. Actual_current - Current draw
5. Overcurrent_limit - Current limit
6. Input_power - Power consumption
7. Motor_speed - Motor RPM
8. Actual_temperature - Temperature reading
9. Overheating_limit - Temperature limit
10. Working_speed - Operating speed
11. Control/alarm - Control and alarm flags

MQTT Topics

Publishing (Telemetry)

Topic: v1/devices/me/telemetry
Format: {"Parameter_name": value}
Example: {"Actual_voltage": 220}

Subscribing (Attributes)

Topic: v1/devices/me/attributes
Format: {"MControl": value}
Example: {"MControl": 1}

ThingsBoard Setup

1. Create a new device in ThingsBoard
2. Copy the device access token
3. Configure the token in menuconfig
4. Create dashboard widgets for telemetry visualization
5. Create shared attributes for remote control

Troubleshooting

SIM7600 Not Responding

• Check UART connections (TX/RX swapped?)
• Verify power supply (5V, sufficient current)
• Check SIM card insertion
• Monitor STATUS pin (should go HIGH after boot)

Network Registration Failed

• Verify SIM card has data plan
• Check APN settings for your carrier
• Ensure good signal strength (check RSSI)
• Try manual network selection

Modbus Communication Error

• Verify RS485 wiring (A, B terminals)
• Check baud rate matches pump controller
• Verify slave address is correct
• Check RW pin logic (HIGH=TX, LOW=RX)
• Use Modbus simulator for testing

MQTT Connection Failed

• Verify ThingsBoard token is correct
• Check broker address and port
• Ensure network connection is active
• Monitor serial output for error codes

Serial Monitor Output

Expected startup sequence:

I (1000) SGW01_SIM7600: ********************************* SYSTEM INFO *********************************
I (1050) SGW01_SIM7600: >> Free memory: XXXXX bytes
I (1100) SGW01_SIM7600: >> IDF version: vX.X
I (1150) sim7600_task: Starting SIM7600 task
I (1200) modbus_task: Starting Modbus task
I (1250) mqtt_task: Starting MQTT task
I (2000) sim7600_task: Powering on SIM7600...
I (22000) sim7600_task: Modem is ready!
I (25000) sim7600_task: Network registered (status: 1)
I (26000) sim7600_task: Signal quality: RSSI = 25
I (27000) sim7600_task: MQTT connected successfully
I (28000) mqtt_task: Subscribed successfully
I (30000) modbus_task: Read successful: V=220, I=13, P=2200, T=22
I (30200) mqtt_task: Published successfully (state 0)

Project Structure

sgw01_v1.0.0/
├── components/          # Custom ESP-IDF components
│   ├── sim7600_driver/  # SIM7600 modem driver
│   ├── modbus_rtu/      # Modbus RTU master
│   └── solar_pump/      # Solar pump data management
├── main/                # Main application
│   ├── app_main.c       # Entry point
│   ├── sim7600_task.c   # Modem management
│   ├── modbus_task.c    # Modbus communication
│   └── mqtt_task.c      # MQTT publish/subscribe
├── CMakeLists.txt       # Project build config
└── sdkconfig            # ESP-IDF configuration

Development

Adding New Parameters

1. Update solar_pump_data_t structure in solar_pump.h
2. Add parameter name to param_names[] array
3. Update solar_pump_read_all() to read new register
4. Add new case in MQTT publish state machine

Modifying MQTT Topics

1. Update Kconfig.projbuild with new topic defaults
2. Rebuild and reconfigure via menuconfig
3. Update ThingsBoard dashboard accordingly

Changing Publish Strategy

Currently publishes one parameter at a time. To publish all at once:

1. Use solar_pump_create_json_all() instead of solar_pump_create_json_single()
2. Remove state machine from mqtt_task.c
3. Adjust publish interval accordingly

License

Copyright © 2026 Myannovation. All rights reserved.

Author

Ye Min Htwe
Myannovation
January 2026

Support

For technical support or questions:

• Review IMPLEMENTATION_SUMMARY.md for detailed documentation
• Check ESP-IDF documentation: https://docs.espressif.com/
• Examine component source code for implementation details

Version: 1.0.0
Last Updated: January 17, 2026