JDY‑31 Bluetooth Serial SPP Module Bluetooth3.0 UART Transparent Transmission Compatible HC‑05 HC‑06 For Arduino STM32 IoT Electronic DIY Smart Home Project

JDY‑31 Bluetooth 3.0 SPP Serial Port Module

📌 Product Overview

The JDY‑31 Bluetooth module adopts Bluetooth 3.0 SPP protocol, supports transparent data transmission under Windows, Linux and Android systems. It works on 2.4GHz frequency band with GFSK modulation. Max transmission power reaches 8dB, and the communication distance can be up to 30 meters. Users can modify device name, baud rate, password and other parameters through serial AT commands for flexible configuration. This module only works as Bluetooth slave device. Two hardware versions are available: SMD bare chip version and pin‑header baseboard version. SMD module works at 1.8‑3.6V (recommended 3.3V); baseboard version supports 3.6‑6V power input (recommended 5V). It adopts built‑in PCB antenna, features low power consumption, fast searching and fast connection performance, higher throughput compared with JDY‑30. It exposes UART serial port (TTL level), STATE connection status pin, easy to connect with MCU for serial transparent transmission projects.

📋 Main Specifications

• Model: JDY‑31
• Bluetooth Version: Bluetooth 3.0 SPP
• Operating Frequency: 2.4GHz
• Modulation Mode: GFSK
• Communication Interface: UART(TTL)
• Power Supply:
  • SMD Version: 1.8‑3.6V (recommended 3.3V)
  • With Baseboard: 3.6‑6V (recommended 5V)
• Operating Temperature: -40℃ ~ +80℃
• Antenna: Built‑in PCB Antenna
• Max Transmission Distance: 30m
• Role: Slave Only
• SMD Soldering Temperature: <260℃
• Standby Current(Unconnected): 4.7mA
• Connected Working Current: 7.3mA
• Max Transmit Power: 8dB
• Receiving Sensitivity: -97dBm
• SPP Max Throughput: 16K bytes/s (Android, Windows)

📍 Pin Definition (Baseboard Version)

• STATE: Connection status pin, low level for disconnected, high level for connected
• RXD: Serial data input pin (TTL level)
• TXD: Serial data output pin (TTL level)
• GND: Ground
• VCC: Power supply
• EN: Reserved empty pin

⚙️ AT Command Set

Configure parameters via serial port AT commands, remember to add line‑ending character when sending commands:

1. AT+VERSION: Query firmware version, default JDY‑31‑V1.2
2. AT+RESET: Soft reset module
3. AT+DISC: Actively disconnect existing bluetooth connection (valid under connected status)
4. AT+LADDR: Query module MAC address
5. AT+PIN: Set & query connection password, default 1234
6. AT+BAUD: Set & query serial baud rate, default 9600
7. AT+NAME: Set & query broadcast device name, default JDY‑31‑SPP
8. AT+DEFAULT: Restore factory default settings

✅ Feature Highlights

1. Two optional hardware forms: SMD patch and pin‑header baseboard, convenient for different embedded design demands
2. Ultra‑low working current 7.3mA after connection, better power‑saving performance than JDY‑30
3. Max throughput up to 16K bytes/s, fast bluetooth searching and rapid connection
4. Complete AT command system, freely modify name, baud rate, password and restore factory settings
5. STATE status pin output, external MCU can detect bluetooth connection status
6. Classic SPP profile, widely compatible with Android mobile phone, Windows/Linux computer bluetooth serial assistant

🛠 Application Scenarios

• Bluetooth serial transparent transmission for Windows PC
• Android bluetooth serial communication
• Smart home control system
• Automobile OBD detection equipment
• Bluetooth controlled toys
• Shared power bank, shared weighing scale
• Medical instrument bluetooth data transmission

📏 Physical Dimension

• With Baseboard Version: 45*16mm, Weight 3.6g
• SMD Bare Module: 27*13mm, Weight 0.7g

⚠ Important Usage Notice

Kind reminder: If there are version differences or images not been updated, please refer to the actual product.

1. This module only supports slave mode, cannot work as master bluetooth device
2. Pay attention to power voltage distinction: SMD version cannot accept 5V directly, baseboard version supports 3.6‑6V input
3. When sending AT commands, serial tool must enable send‑on‑enter function, otherwise AT instructions will not take effect
4. Keep away from strong electromagnetic interference environment to guarantee stable communication distance.