Little pause writing a .CSV - Raspberry Pi Forums

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hi,

reading sensor values , writting them in csv file in 200hz, have detected program stops while writing in .csv. not know why happens because isolate case. why be?

code: select all

  ofstream fs(filename_map.str());  			//save data - general information excel file 			time_total = (millis()-reference)/1000.0;  			fs << i++ << ",0,0,0," << setprecision(3) << @ << ","; 			fs << fixed << setprecision(2) << x << "," << y << "," <<  z << "," << setprecision(5) << velocity << "," << yaw << ","; 			fs << setprecision(1) << timehour << "," << setprecision(0) << date << "," ; 			fs << setprecision(5) << longitude << "," << latitude << "," << altitude << ","; 			fs << setprecision(3) << time_total << endl;

you might think writing file 200 times second os don't write changes sd-card every time. contents stored in file buffer/cache , @ point os think time push flash , can take variable amount of time.

if need avoid such pauses, might need have reading in 1 thread , writing file in another, , use ringbuffer/stack keep values. if running on singe core rpi (a/b/b+) might never avoid such events.


raspberrypi



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