This paper explores how inertial Pedestrian Dead-Reckoning (PDR) location systems can be improved with the use of a light sensor to measure the illumination gradients created when a person walks under ceiling-mounted unmodified indoor lights. The process of updating the inertial PDR estimates with the information provided by light detections is a new concept that we have named Light-m... https://www.bekindtopets.com/flash-find-Expansion-Board-2-0-for-Pycom-IoT-Development-Boards-Discontinued-clearance/