while (1) {
     next_time=time+60; 
     get_data_taking_55_seconds_give_or_take_a_few;
     sleep next_time-time;
     write_log_file;
}

##</code><code>##

next_time=time;
while (1) {
     next_time=next_time+60; 
     get_data_taking_55_seconds_give_or_take_a_few;
     sleep next_time-time;
     write_log_file;
}