What does LED1 do while the signal goes out to LED2 and then LED3?
its unlit for 4mS of a 6mS drive signal period . pov makes the gap invisible at that rate


the pwm freq is 2kHz the isr switches the pwm drive @ 2mS intervals . for a pov objective its quite effective
its basically the same as how a 1/4 scan or a 1/8 scan led panel works, except its 1/3 scan

try it .