I'm having trouble controlling red/green LED. I need to control it from my MCU with one pin. The pin can pull-up or pull-down and the LEDs can be with common cathode or anode. I'm flexible on that.
I tried to do with two NPN transistors but I can only get LED1 to be ON or both LED1 and LED2 to be ON. I think I should be using one NPN and one PNP transistor but I cant figure it out at this point. Should I use bipolar LED? When should bipolar LED be used and when duo led?