I have encountered a problem with running the potentiometer-controlled servo.
The circuit connections were checked physically (visual inspection x 3) and electrically – with continuity tester for connections to power-supply terminals and the Arduino pins
The output from the potentiometer wiper was checked with a 4 ½ digit autoranging multimeter to check that it was 1) connected properly to +5V supply, 2) outputting a variable voltage. The pot wiper is outputting a variable voltage from 0V dc to 4,77V dc depending on wiper position, which seems correct.
No other connections are relevant and all connectivity has been checked.
Uploading the program compiles without notified errors and uploads (apparently) correctly –
Observations: 1) upon upload, the servo shocks three times and positions itself at roughly 85 degrees; when settled there, it remains constant and no potentiometer input makes any difference to it although the voltage can be seen to vary from the pot wiper.
The previous simple experiment (servo sweep) operates correctly therefore the servo is operational.
Recompiling and re-uploading the program does not solve the problem.
It would appear to me therefore, that with all components intact and interconnectivity intact and properly connected, there is something amiss with the program itself.