Validity and reliability - Single beam photocell - Appendix A - Code and hardware schematics

Appendix A. Study´s source code, and hardware schematics. A single beam photocell system prototype was built especially for this study. It consisted of three infrared light-emitting devices and three receiving devices each with a photoelectric sensor (50 milliseconds time response). A lithium battery was installed at devices. One receiving device was defined as central command with: a) a central information processing module; b) LCD (Liquid Crystal Display) screen configured as a digital stopwatch (two decimal places), providing a temporal resolution of 1÷100 = 0.01 s; c) buttons to system operating. The ESP-NOW radio protocol was used for communication between devices. For the electronic development of the system, the Proteus software (Version 8.3) was used. The algorithm for calculating the time of the first half of the sprint and the total sprint was written in the Arduino software (Version 1.8.1).