IEEE 802.15.4 is a widely adopted foundation for the lower layers of wireless sensor networks. This standard has recently started to take localization into account. This has led to the addition of two new PHY layers, Ultra-Wide Band (UWB) and Chirp Spread Spectrum (CSS), but also the specification of a Time Of Flight-based ranging protocol named Symmetric Double-Sided Two-Way Ranging (SDS-TWR). This paper describes the results obtained from a CSS-based prototype using a variant of SDS-TWR. Our solution differs from others exploiting the same tools by not involving a localization server. The location estimation algorithm is executed by the mobile node, right after the ranging phase. The obtained localization error is generally under 200cm in 90% of the situations and the mean error is around 1m.