I bought two cheap Mearm robot arms with included Unos (clones) and joystick boards. The joystick boards act very strangely to me. One board consists of two joysticks:
One joystick has two trimpots with the code 103, so they should be 10 kOhm, right? But when I measure the pins directly on the board, the far most pins of each potentiometer gives some 2.3 kOhm. When I measure the middle pin (the sweeper) and either of the other pins, I get some 3.7 kOhm.
What I'd expect is that the far most pins give 10 kOhm and the middle one would give 5 kOhm when in rest. And the middle one would change linearly when the joystick is twisted. Now the middle one changes from 3.7 kOhm towards zero, when I turn the joystick to one side. But when I turn it to the other side, the value first arises to almost 5 kOhm, then it drops to some 2.3 kOhm at the far edge. What's going on here? Is this intended behaviour or do all 8 pots in the 2 joystick boards happen to have same fault? If it's intended, what is the purpose of it? As it is, when my program gets a reading like 520, I can't tell whether the joystick is in the middle or at the far edge.