Integration of algorithms and protocols from different layers will make possible the deployment of large-scale wireless sensor networks. The growing number of nodes that comprises within these networks requires a correct organization and an efficient node synchronization to ensure data reliability. In this study, we focus on the integration of fuzzy-logic based routing with a TDMA MAC protocol. By considering the experimental results of them working separately, we have integrated them to work together, so forming a cross-layer framework. By using a fast configuration and efficient slot assignment from the MAC protocol, and the accuracy of the logical tree created by fuzzy logic based routing, nodes in the network are both organized and synchronized, while load balance is achieved to extend network lifetime and provide efficient communications