SdFAT rewrite

[asleepinverona]

Hi all!

I am trying to move within a file on an SD card and it just doesn't seem to be working. Here is my code to move inside the file:

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  file_size=f.fileSize();
              f.seekSet(file_size-200);

Then I am trying a simple write operation:

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 f.write(data);

where data is some data I've gotten from the ADC. No matter what happens, I am only able to print at the end of the file, and not a previously written section. Any Ideas?

I've looked at the SDFATLIB Rewrite example and it didn't clear up anything for me. I'm clearing the write error. I tried using "print" instead of "write"

Thanks!

[fat16lib]

It would help if you posted more code.

Before posting the code try this to get more information. Replace the seekSet call with

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  if (!f.seekSet(file_size-200)) Serial.println("seekSet failed");

Also check writeError after the write

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  if (f.writeError) Serial.println("write failed");

[asleepinverona]

I found out what the problem was. I was not opening the file correctly:

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f.open(&root,file_title_buffer,O_APPEND|O_WRITE);

versus

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f.open(&root,file_title_buffer,O_RDWR);

Thanks!