Good morning, my name is Marco, congratulations for the fantastic site !!!
I am a self-made hobbyist for curiosity
I wanted to try the pid controller (http://electronoobs.com/eng_arduino_tut24_2.php
unfortunately, I can not understand why in the compilation phase, IDE gives me this error
Arduino: 1.8.7 (Windows Store 188.8.131.52) (Windows 10), Card: "Arduino / Genuino Uno"
sketch_sep15a: 52: 7: error: redefinition of 'float last_kp'
float last_kp = 0;
sincerely greetings I hope to solve