I have a Nano mounted on an expansion board to control a single servo - for experiments. The sketch I am using worked fine the last time I used it.
I have an expansion board mounted with a servo connected to pin 3 and the corresponding input pin is either Hi or Lo according to a switch.
The sketch uploads and I see the TX/RX leds flash. When the pin is Lo I see the power light on the Nano, when I operate the switch, the 'L' led comes on and stays on until the pin is LO.
I checked the voltage on the SIG pin and on power up it indicates a signal which then drops to zero. This moves the servo to the centre position as desired. Operating the Hi/Lo switch shows no change on the SIG pin.
This is confusing as all this worked fine a few months back and I have tried with a couple of brand new Nanos.
What could be happening and how do I find out?