arXiv:2608.29036v2 Announce Type: replace Abstract: Wireless body area networks (WBANs) underpin the Internet of Medical Things (IoMT). IEC/ETSI SmartBAN defines a lightweight time-division multiple access (TDMA) protocol, yet published implementations on commercial hardware remain partial. The standard specifies frame formats but leaves device-internal behavior in phase control, connection lifecycle, and slot timing unspecified. We present an operational SmartBAN realization on a commercial wireless system-on-chip (Nordic nRF54L15, Arm Cortex-M33, Zephyr RTOS) that implements initial connection, scheduled uplink, and timeout-based disconnection detection through a four-layer software architecture whose hardware abstraction layer is the intended portability boundary. Hub and Node Mealy automata supply one concrete design for the unspecified phase control and connection lifecycle, as a blueprint for the firmware's event-driven dispatch. Validation with 16 concurrent Nodes over 25 hours shows conformance across every transition the build exercises (all but one), >99.99% packet delivery, and timeout-triggered reconnection after the single observed disconnection. An analytical current model fits the measurements once it uses measured state currents; with datasheet currents it underestimates the average, mostly in the radio-off state, whose current we attribute to implementation-level overhead rather than the hardware. A same-SoC comparison with Bluetooth Low Energy (BLE) shows how each protocol departs from its schedule: SmartBAN, configured to send a fresh sample every interval instead of retransmitting, kept each Node's frame spacing within 1.1 ms of the interval but lost some frames; BLE lost none but deferred some by one or two intervals, and drew less than half SmartBAN's average current.