Industrial wireless sensor and actuator networks are gaining momentum and have started to target new and more demanding application scenarios extending pure monitoring scenarios. In this paper we discuss the needs for simple and more accurate TDMA timing synchronization to enable the future applications. We present a novel TDMA timing synchronization protocol which is simple to implement, as well as a performance evaluation using of-the-shelf hardware indicating measured worst case synchronization errors less than 10 microseconds at five hops from the synchronization master. The paper shows that it is possible to realize synchronization on average around 1 microsecond with little effort and negligible computational or network overhead.