This blog post is part of a series exploring the development of real-time iBeacon and beacon technology using the Tessel platform, focusing on enhancing capabilities with bidirectional communication. The installment details how to use the Tessel board, a JavaScript-powered microcontroller, as both a detector and emitter beacon, leveraging the Tessel BLE Module for beacon technology. It explains the structure of beacon advertisements according to the Bluetooth v4 specification, including the composition of AD structures and the specific data formatting required for beacon communication, such as in the AltBeacon protocol. The post describes how beacons can approximate device distance by comparing RSSI values and provides guidance on implementing Tessel-based beacon functionality with JavaScript, highlighting the ease of advertising and detecting beacons without the need for complex SDKs.