Supported Targets	ESP32	ESP32-C2	ESP32-C3	ESP32-C6	ESP32-H2	ESP32-P4	ESP32-S2	ESP32-S3

ESP32 SSR Timer Multiple Channel

How to use example

We encourage the users to use the example as a template for the new projects. A recommended way is to follow the instructions on a docs page.

Example folder contents

The project sample_project contains one source file in C language main.c. The file is located in folder main.

ESP-IDF projects are built using CMake. The project build configuration is contained in CMakeLists.txt files that provide set of directives and instructions describing the project's source files and targets (executable, library, or both).

Below is short explanation of remaining files in the project folder.

├── CMakeLists.txt
├── main
│   ├── CMakeLists.txt
│   └── main.c
└── README.md                  This is the file you are currently reading

Additionally, the sample project contains Makefile and component.mk files, used for the legacy Make based build system. They are not used or needed when building with CMake and idf.py.

Overview

This project involves controlling a 4-Channel Relay Module using an ESP32-S3 microcontroller. The relays can handle 110220VAC or 332VDC. The system communicates via MQTT to manage multiple channels, each with three non-overlapping operating periods. Each period includes configurable parameters such as start time, stop time, running duration, interval duration, and number of runs.

Hardware

• Microcontroller: ESP32-S3
• Relay Module: 4-Channel Relay Module (compatible with 110220VAC, 332VDC)
• Power Supply: Ensure proper voltage for ESP32-S3 and relay module
• Network: Wi-Fi for MQTT communication
• NVS: The nvs mechanism is used. All setting parameters will be permanently stored in the device.
• Remote OTA: Support remote update.

Software Requirements

• Platform: ESP32-IDF
• Libraries:
  • mqtt (for MQTT)
  • WiFi (for ESP32 Wi-Fi connectivity)
  • cJSON (for parsing MQTT JSON payloads)
• MQTT Broker: e.g., Mosquitto, HiveMQ, or any cloud-based MQTT service

System Description

Each of the four relay channels can be independently controlled. Each channel supports three operating periods per day, and these periods must not overlap. The parameters for each period include:

• Start Time (st_time): When the period begins (e.g., "00:01").
• Stop Time (sp_time): When the period ends (e.g., "08:59").
• On Duration (on_dur): Duration the relay is ON in seconds (e.g., "30").
• Interval Duration (intv_dur): Time between ON cycles in seconds (e.g., "10").
• Count (cnt): Number of ON/OFF cycles (e.g., "4002").
• Period Enable (period_en): Enable/disable period (1 = enabled, 0 = disabled).
• Mode (mode): Operation mode (e.g., "2" for timer-based control).
• !!! ctrl: channelId-periodId

MQTT Communication

The system uses MQTT to receive configuration commands. Each message is a JSON payload specifying the channel, period, and parameters. Below are example payloads for a single channel's three periods: [ Reserve one channel (CH5) ]

Period 1

{
	"id":	"0",
	"sn":	"123",
	"label":	"switch valve",
	"label_en": "multiple channels",
	"ctrl":	"2-1",
	"params":	[
		{"name": "st_time", "value": "00:01"},
		{"name": "sp_time", "value": "08:59"},
		{"name": "on_dur", "value": "30"},
		{"name": "intv_dur", "value": "10"},
		{"name": "cnt", "value": "4002"},
		{"name": "period_en", "value": "1"},
		{"name": "mode", "value": "2"}
	]
}

Period 2

{
	"id":	"0",
	"sn":	"123",
	"label":	"switch valve",
	"label_en": "multiple channels",
	"ctrl":	"2-2",
	"params":	[
		{"name": "st_time", "value": "10:33"},
		{"name": "sp_time", "value": "14:59"},
		{"name": "on_dur", "value": "30"},
		{"name": "intv_dur", "value": "10"},
		{"name": "cnt", "value": "4002"},
		{"name": "period_en", "value": "1"},
		{"name": "mode", "value": "2"}
	]
}

Period 3

{
	"id":	"0",
	"sn":	"123",
	"label":	"switch valve",
	"label_en": "multiple channels",
	"ctrl":	"2-3",
	"params":	[
		{"name": "st_time", "value": "17:33"},
		{"name": "sp_time", "value": "23:59"},
		{"name": "on_dur", "value": "30"},
		{"name": "intv_dur", "value": "10"},
		{"name": "cnt", "value": "4002"},
		{"name": "period_en", "value": "1"},
		{"name": "mode", "value": "2"}
	]
}

MQTT Topics

• Subscribe Topic: device/<sn>/control (e.g., device/123/control)
  • The ESP32 subscribes to this topic to receive configuration updates.
• Publish Topic: device/<sn>/status (e.g., device/123/status)
  • The ESP32 publishes relay status or confirmation of received commands.

Setup Instructions

1. Hardware Setup:

   • Connect the 4-Channel Relay Module to the ESP32-S3 GPIO pins (e.g., GPIO 4, 5, 6, 7 for relays 1-4).
   • Power the ESP32-S3 and relay module appropriately.
   • Ensure the relay module is compatible with the load (110220VAC or 332VDC).

2. Software Setup:

   • Install the required libraries in your development environment.
   • Configure Wi-Fi credentials and MQTT broker details in the code.
   • Parse incoming JSON MQTT messages to extract period parameters.

3. MQTT Broker:

   • Set up an MQTT broker (local or cloud-based).
   • Ensure the ESP32 can connect to the broker over Wi-Fi.

Operation

• The ESP32 listens for MQTT messages on the subscribed topic.
• When a valid JSON payload is received, it updates the corresponding channel and period settings.
• The system checks the current time against each period’s start and stop times.
• If within a period and enabled, the relay operates based on the on_dur, intv_dur, and cnt parameters.
• Status updates (e.g., relay ON/OFF) are published to the status topic.

Example Workflow

1. An MQTT message is sent to device/123/control with the Period 1 configuration for Channel 2.
2. The ESP32 parses the JSON, validates the ctrl field (e.g., "2-1" for Channel 2, Period 1), and stores the parameters.
3. Between 00:01 and 08:59, Channel 2’s relay turns ON for 30 seconds, OFF for 10 seconds, repeating 4002 times or until the stop time is reached.
4. The ESP32 publishes a status update to device/123/status confirming the operation.

Notes

• Ensure periods do not overlap to avoid conflicts (e.g., Period 1 ends at 08:59, Period 2 starts at 10:33).
• Validate MQTT payloads to prevent invalid configurations.

Future Improvements

• Add local storage (e.g., SPIFFS) to save configurations during power loss.
• Implement a web interface for manual configuration.
• Support dynamic channel and period allocation via MQTT.