Accurate characterization of real device samples is essential for understanding the true potential of the emerging non-volatile memories (NVMs) and identifying their optimal placement in the memory hierarchy. Even though, NVM devices are now available from different manufacturers, lack of an appropriate NVM controller and evaluation platform in the public domain is the main challenge in extracting empirical data from these real devices. In this paper, we present Open-NVM, an open-sourced, highly configurable FPGA based evaluation/characterization platform for various NVM technologies. Through our OpenNVM, this work reveals important low-level NVM characteristics, including i) static and dynamic latency disparity, ii) error rate variation, iii) power consumption behavior, vi) interrelationship between frequency and NVM operational current. In addition, we also examine state-of-The-Art write-once-memory (WOM) codes on a real NVM device and study diverse system-level performance impacts based on our findings. All FPGA source code and detailed information of our hardware design is ready to be open-sourced and downloaded for free.