Silicon labs bluegiga rf modules silicon labs bluegiga ble121lr a m256k the bt121 is a bluetooth smart ready module targeted for applications that require both bluetooth smart and classic connectivity it can connect to legacy devices that only support bluetooth spp or apple iap2 profiles as well to devices that support bluetooth smart bt121 integrates a high performance bluetooth radio a low power arm cortex micro controller and a bluegiga bluetooth smart ready stack software marking it ex