LouisSnz:
One thing I've noticied is that the function Serial.println("..."); takes a lot of time (around 5 ms). With this code, I take my values every millisecond.
I saw that we could make up to 10,000 value readings per second. Do you have any ideas to further optimize my code?
It was suggested in both Reply #3 and Reply #4 to write the values as binary to the file. You ignored those suggestions.