Hello, First some project info... I'm building a small pressure data logger for my agricultural sprayer. It contains a Nano, pressure sensor, RTC clock, SD card, 16x2 LCD and one button. Every second the pressure sensor is read, displayed on the LCD and stored in a 10 places array. Every 10th se…

I have not use an SD card. But, if your record lengths are ALL identical, you can use a random access method by seeking a record number and reading that record. Research it. Paul

bertschermers: Do I need a different library with more functions?? I don't think there would be one that does exactly what you want. bertschermers: Do I have to write the file upside down: the last log as first line instead of the last line?? That's practically impossible. You can either ov…

Hello, I have found the answer for the problem: using SD.size() and SD.seek() is the solution. but this will only work with a fixed String length I made a testdatabase of 2500 lines and the following code: myFile = SD.open("TESTDATA.txt", FILE_READ); //file open, in read modus // Serial.pr…

bertschermers: but this will only work with a fixed String length. That's what Paul_KD7HB and I were talking about; now you know why. bertschermers: I made a testdatabase of 2500 lines and the following code: myFile = SD.open("TESTDATA.txt", FILE_READ); //file open, in read modus // Se…

hello lucario448, thanks for the reply, I made a string (record) for one line on a 16x2 LCD with date time and pressure (with comma and one decimal): ddmm_hhmm:ss_p,p the gaps in date and time when the numbers are <10 were filled with a "0" (zero), so the string is always exact 16 caracters I ma…

bertschermers: I made a testfile with 2500lines of 16 characters and count the characters with SD.size() when I divided the outcome by 2500, it says 18!! One extra char should be the carriage return, the last one I really do'nt know. Every line ends with the two-character sequence "\r\n" (carr…

that explains why every 16 number record counts 18 characters. I think that's a lack of my basic programming knowledge... Thanks!!

a 16 character String in the format "ddmm_hhmm:ss_p,p" how I cut 8 characters per file: I make the file name "YEARMMDD.CSV" There is no point saving the date in every file when the file name can serve as the date, and the file name is automatically generated or opened when you write. here's the …

How can I find and read the last lines of a large .txt file on an SD card?

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How can I find and read the last lines of a large .txt file on an SD card?

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