Firmware for FC-209 kit in English, LED clock with rotating sphere. This video is dedicated to fans of channel who don’t understand Spanish language, but they’re interested in some assemblies that have presented on the channel.
English firmware: J_RPM_v5e_EC1204B.HEX
The explanation about how working of all components contained in this circuit, not going to repeat in English, because the manufacturers documentation is already in English … and is much fuller than that I could explain here.