The paper presents a preliminary approach for the modeling and simulation of a complete wireless sensor network with two nodes using SystemC-AMS, an open-source C++ library dedicated to the description of heterogeneous systems containing digital, analog, RF hardware parts as well as embedded software. The WSN node, or mote, detailed herein consists of a physical sensor, a continuous time sigma-delta converter with its associated decimation filter, an ATMEGA128 8-bit microcontroller running the embedded application and a QPSK-based 2.4 GHz RF transceiver. The paper starts with the structural description of the system as a hierarchical set of behavioural modules, then gives an insight on how multi-frequency simulation is handled in SystemC-AMS, and finally presents simulation results that are systematically compared with the Matlab reference in terms of accuracy and simulation time.