smartxp wiki

Bluetooth HM-10 CC2541 Bluetooth 4.0 Module

This bluetooth 4.0 module has a lot of functionality built in, including sending as an iBeacon or for standard
serial communication.
In addition, the software on the module can be upgraded to get more functionality.

Specifications:
Voltage (power supply): 3.6 - 6V DC
Voltage (signals): 3.3V-5V (level converter built in)

https://www.instructables.com/How-to-Use-Bluetooth-40-HM10

Getting Started with the HM-10 BLE Module written by Jarrod Smith, Department of Electrical and Computer Engineering California State University, Fresno https://engineering.fresnostate.edu/research/bulldogmote/documents/11.%20HM10%20BLE_FTDI.pdf