DS18B20 Digital Temperature Sensor

Overview

DS18B20 is a 1-Wire (OneWire) digital temperature sensor with a measurement range of -55°C to +125°C and accuracy of ±0.5°C. Multiple sensors can be mounted on the same bus.

Supported Peripheral Types

Type	type Value	Sensor Category
SENSOR	38	SENSOR_DS18B20 (5)

Hardware Wiring

DS18B20 Pin	Connection	Description
VCC	3.3V / 5V	Power supply
GND	GND	Ground
DQ	GPIO + 4.7KΩ pull-up to VCC	Data line

The data line must have an external 4.7KΩ pull-up resistor to VCC, otherwise communication will be unstable.

Configuration

Method 1: Web Interface Configuration (Recommended)

Before saving DS18B20 configuration, verify OneWire pin, pull-up resistor, and sensor ID.

Step 1: Navigate to Peripheral Management Page

1. Open a browser and navigate to the ESP32 IP address
2. After logging in, click Peripheral Configuration in the left menu

Step 2: Add DS18B20 Peripheral

1. Click the Add Peripheral button

2. Fill in the configuration:

   Field	Value	Description
   Peripheral ID	ds18b20_1	Unique identifier
   Name	Water Temperature Sensor	Display name
   Peripheral Type	Generic Sensor (type: 38)	DS18B20 driver
   Pin Configuration	4	DQ data pin
   Sensor Category	DS18B20	Temperature sensor
   Sampling Interval	2000	2 seconds (≥750ms)

3. Click Save

Step 3: Verify Configuration

1. Find the newly added peripheral in the peripheral list
2. Click the Enable toggle
3. Wait 2 seconds and check temperature data

⚠️ Important: Data line must have an external 4.7KΩ pull-up resistor to VCC

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Method 2: JSON Configuration File Import

Add the following configuration to the peripherals array in data/config/peripherals.json:

Single DS18B20

{
  "id": "ds18b20_1",
  "name": "Water Temperature Sensor",
  "type": 38,
  "enabled": false,
  "pins": [4],
  "params": {
    "sensorType": 5,
    "sampleInterval": 2000
  }
}

Parameter Description

Parameter	Description
sensorType	Sensor category: 5 = DS18B20
sampleInterval	Sampling interval (ms), minimum 750ms (conversion time)

Peripheral Execution Integration

Web Interface Configuration Steps

Create Timed Collection Rule

1. Switch to the Peripheral Execution Management tab
2. Click the Add Rule button
3. Configure timer trigger:
   • Trigger Type: Timer Trigger
   • Execution Interval: 60 seconds
4. Add action:
   • Action Type: Sensor Read
   • Target Peripheral: ds18b20_1
5. Enable Report Data After Execution
6. Click Save

Create Temperature Threshold Alarm Rule

1. Create a new rule
2. Configure platform trigger:
   • Trigger Type: Platform Trigger
   • Data Source: ds18b20_1
   • Comparison: Greater Than
   • Comparison Value: 60
3. Add action:
   • Action Type: High Level
   • Target Peripheral: buzzer (buzzer)
4. Click Save

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JSON Configuration Example

Timed Temperature Collection

{
  "id": "exec_ds18b20_read",
  "name": "Timed Water Temperature Collection",
  "enabled": false,
  "execMode": 0,
  "triggers": [
    {
      "triggerType": 1,
      "triggerPeriphId": "",
      "operatorType": 0,
      "compareValue": "",
      "timerMode": 0,
      "intervalSec": 60,
      "timePoint": "",
      "eventId": "",
      "pollResponseTimeout": 1000,
      "pollMaxRetries": 2,
      "pollInterPollDelay": 100
    }
  ],
  "actions": [
    {
      "targetPeriphId": "ds18b20_1",
      "actionType": 19,
      "actionValue": "",
      "useReceivedValue": false,
      "syncDelayMs": 0,
      "execMode": 0
    }
  ],
  "protocolType": 0,
  "scriptContent": "",
  "reportAfterExec": true
}

Temperature Threshold Alarm

{
  "id": "exec_ds18b20_alarm",
  "name": "Water Temperature Over-limit Alarm",
  "enabled": false,
  "execMode": 0,
  "triggers": [
    {
      "triggerType": 0,
      "triggerPeriphId": "ds18b20_1",
      "operatorType": 2,
      "compareValue": "60",
      "timerMode": 0,
      "intervalSec": 60,
      "timePoint": "",
      "eventId": "",
      "pollResponseTimeout": 1000,
      "pollMaxRetries": 2,
      "pollInterPollDelay": 100
    }
  ],
  "actions": [
    {
      "targetPeriphId": "buzzer",
      "actionType": 0,
      "actionValue": "",
      "useReceivedValue": false,
      "syncDelayMs": 0,
      "execMode": 0
    }
  ],
  "protocolType": 0,
  "scriptContent": "",
  "reportAfterExec": true
}

Comparison with DHT Sensors

Feature	DS18B20	DHT11/DHT22
Measured Parameters	Temperature only	Temperature + Humidity
Accuracy	±0.5°C	±2°C / ±0.5°C
Range	-55~125°C	0~50°C / -40~80°C
Interface	OneWire	Single-bus (custom protocol)
Multi-Sensor	Supports multiple on one bus	Each requires independent pin
Waterproof	Available in waterproof package	Not waterproof

Notes

1. Pull-up Resistor: 4.7KΩ pull-up resistor is essential; use smaller pull-up (e.g., 2.2KΩ) for long wire runs
2. Conversion Time: At 12-bit precision, conversion time is approximately 750ms; sampling interval should not be less than this
3. Power Mode: Recommend external power mode (VCC connected to 3.3V/5V); avoid using parasitic power
4. Bus Length: Standard wiring can reach 100m, but signal quality must be considered
5. Multi-Sensor: Multiple DS18B20 sensors can be connected to the same pin, distinguished by ROM address