ok, so changing one thing, and one thing only, at a time… Can you write 80 bytes per write, every second? 100 bytes every second? 120? 140? 160? 180? 240?
That proves your code works for those byte counts.
Then, for 40 bytes per write, can you do that every second, then twice per second, then 3x per sec, etc.
Using this will show you the limits of your code/microcontroller/SD card that you have.
I asked, because in your original post you said:
[quote=“Yuya, post:1, topic:21944”]
But the communication between SD Module and a microcontroller is stopped immediatly after power on[/quote]
which made me wonder if you had no comms to ALFAT at all… but that’s not the case. Go do some more tests and tell us what you find