This paper describes the development of a sport watch, as well as the software and hardware required to design an integrated solution for getting feedback during and after walking and running activities. The developed system is autonomous, so that neither a smartphone nor a computer are necessary for configuration. The user controls the watch via a touch-screen based interface and all the relevant information is displayed on an LCD. Moreover, the watch contains all the required inertial sensors to allow giving different feedbacks to the user, such as the type of activity, the number of steps taken, the covered distance, the instantaneous speed and the average speed. Although this work is multidisciplinary, in this paper the emphasis is put on the description of the device and on the electronics and the algorithms implementation. Particular focus is on the efficiency in terms of computational time, and in achieving high autonomy on a primary cell battery.