Because the JDY-40 is a 3.3V logic device, connecting it directly to a 5V Arduino Uno/Nano requires care. While the RX/TX pins are often 5V tolerant, using a logic level converter or a simple resistor voltage divider on the JDY-40 RXD pin ensures long-term reliability. JDY-40 Pin Arduino Uno/Nano Pin Ensure adequate current supply GND Common ground is mandatory TXD Pin 2 (Software RX) Direct connection RXD Pin 3 (Software TX) Use a 1kΩ / 2kΩ voltage divider SET Pin 4 (or GND for config) Controls AT Command mode CS Keeps module active AT Command Configuration
If your project requires interaction with a smartphone or a standard Bluetooth host, the HC‑05 is more appropriate. For everything else (sensor networks, remote controls, robot‑to‑robot communication), the JDY‑40 is often the better choice. jdy40 arduino example best
After running this sketch once, the module should be ready to communicate with any other JDY‑40 that shares the same channel (5) and ID (1). Remember that some modules lose settings when power is removed, so you may need to run this configuration every time your Arduino starts up. Because the JDY-40 is a 3
A full-duplex communication bridge that allows the user to change the JDY-40 baud rate via Arduino code (removing the need for USB-to-TTL adapters for setup) and provides a "Heartbeat" signal quality indicator . A full-duplex communication bridge that allows the user
Chip Select / Sleep Pin (Pull LOW for normal operation/AT mode, pull HIGH for sleep mode)