CC2541 BLE 4.0 Module

The module runs on Texas Instruments' CC2541 BLE system-on-chip and works as a transparent UART bridge, so data sent from a smartphone app arrives at the microcontroller as plain serial bytes. It is configured with AT commands for name, baud rate, role and pairing, in the same style as the popular HM-10 module. Its logic runs at 3.3 V, so use a level shifter or voltage divider on its RX pin with a 5 V Arduino unless your breakout already includes one. Because it uses Bluetooth Low Energy rather than classic Bluetooth, it works with both iOS and Android for phone-controlled robots and lights, wireless sensor readouts and beacon projects.