Renesas also provides a full Bluetooth low energy proximity tag reference design. A proximity tag works by making a connection to another device such as a Smartphone, Tablet or PC. The two devices then make regular checks to ensure they can still exchange information between each other. Thus, they know they are in range of each other. They can also tell each other about the other devices signal strength during recent data exchanges, and thus provide indications of the relative distance between each other. They create a type of electronic leash between each other; alerting the user when the leash becomes very extended or breaks. The design provides operation for more than 18 months with a connection interval of 500 mS and more than 3.5 years for a connection interval of 2.5 s. It includes an alerting buzzer and the software on the device can be updated by a transfer over the air (SUOTA). By using the DA1450 device, the design is kept low cost and does not require the use of a 32 kHz crystal, thus providing further cost reduction.