Experimental Clock Calibration on a Crystal-Free Mote-on-a-Chip

Ioana Suciu (1) , Filip Maksimovic (2) , David Burnett (2) , Osama Khan (2) , Brad Wheeler (2) , Arvind Sundararajan (2) , Thomas Watteyne (3) , Xavier Vilajosana (4, 1) , Kris Pister (5)

1 Worldsensing
2 UC Berkeley - University of California [Berkeley]
3 EVA - Wireless Networking for Evolving & Adaptive Applications
4 UOC - Universitat Oberta de Catalunya [Barcelona]
5 BSAC - Berkeley Sensor and Actuator Center [Berkeley]

The elimination of the off-chip frequency reference,typically a crystal oscillator, would bring important benefits in terms of size, price and energy efficiency to IEEE802.15.4compliant radios and systems-on-chip. The stability of on-chip oscillators is orders of magnitude worse than that of a crystal.It is known that as the temperature changes, they can drift more than50ppm/◦C. This paper presents the result of an extensive experimental study. First, we propose mechanisms for crystal-free radios to be able to track an IEEE802.15.4 join proxy, calibrate the on-chip oscillators and maintain calibration against temperature changes. Then, we implement the resulting algorithms on a crystal-free platform and present the results of an experimental validation. We show that our approach is able to track a crystal-based IEEE802.15.4-compliant join proxy and maintain the requested radio frequency stability of±40ppm, even when subject to temperature variation of2◦C/min.

Mots clés: IEEE802.15.4; Low-power wireless mesh networking; Clock calibration; Standard-compliance; Crystal-free radio; Short-range wireless; Reference frequency stability

Domaines: Réseaux et télécommunications [cs.NI]; Systèmes embarqués

Ioana Suciu, Filip Maksimovic, David Burnett, Osama Khan, Brad Wheeler, et al.. Experimental Clock Calibration on a Crystal-Free Mote-on-a-Chip. IEEE INFOCOM - CNERT 2019 : International Workshop on Computer and Networking Experimental Research using Testbeds, Apr 2019, Paris, France. ⟨hal-02266563⟩