A key concern in the design of controllers in wireless sensor network (WSN) nodes is the flexibility to execute different control tasks involving sensing, communications and computational resources of the node. In this paper, low power flexible controllers for WSN nodes based on reconfigurable microtasks composed of an FSM and datapath are presented. Coarse grain power gating opportunities are exploited in FSM and datapath for low power operation in reconfigurable microtasks. Power estimation results on typical benchmark microtasks show a 2× to 5× improvement in energy efficiency w.r.t a microcontroller at a cost of 5× relative to a microtask implemented as an ASIC with higher NRE costs.