Here:
void loop() {
...
File logread = SD.open("log.txt", FILE_WRITE);
Where does this file get closed? It's opened every time through loop. And why open for writing anyway? Surely only open for writing when you are updating the cards.
Here:
void loop() {
...
File logread = SD.open("log.txt", FILE_WRITE);
Where does this file get closed? It's opened every time through loop. And why open for writing anyway? Surely only open for writing when you are updating the cards.