Jdy40 Arduino Example Best -

Chip select/Sleep pin. Pull LOW for active operation; pull HIGH to enter low-power sleep mode. Wiring the JDY-40 to an Arduino

2.2V to 3.6V ( 3.3V recommended ; do not use 5V directly). Communication: Standard TTL Serial (UART). Range: Up to 120 meters in open sight. jdy40 arduino example best