Okay, I do not know if I understand you at all, so, I'm going to start going step by step:
First, when I save the array of the positions of the motors on the SD card (something like this: [2344, 4567, 6353, 5335, ...]), when I want to open the file , how can I know how many positions there are? ? Could a sizeof () be used?
Also, how could I control how often the positions are saved in the SD?
Thank you,
Urko