micro sd read write

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TheBeginner

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Subject:

Re: micro sd read write

· Posted: 24.04.2021 - 20:58 · #9

Hello Merlin,
I understood that tomorrow, I'll write the new code. It's over for today.
==================
Hallo Merlin,
das habe ich verstanden morgen gehts weiter, dann schreibe ich den neuen Code. Für heute ist schluss.

Gruß Frank

Harry

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Subject:

Re: micro sd read write

· Posted: 24.04.2021 - 21:34 · #10

Hallo,

eine Frage zwischendurch: Hat einer von euch schon mal eine SD-Karte bei laufendem uC gesteckt oder gezogen? Natürlich kontrolliert also kein Zugriff auf die SD. Wie habt ihr das gemacht? Spannung der SD vorher abgeschaltet?

Gruss
Harry

golf

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Subject:

Re: micro sd read write

· Posted: 25.04.2021 - 05:44 · #11

Hallo Harry,
ich hab mal einen Audio (Infraschall)-Recorder gebaut mit einstellbaren Sampleraten 8000,4000,2000,...,250 Hz. Wollte den Lärm der anliegenden Bundesstraße mal dokumentieren. Da hab ich oft nach Aufnahme Stop die SD-Karte bei Stromversorgung der Platine gezogen und über den PC die aufgezeichneten Wavefiles angeschaut. Das gab bei mir keine Probleme.
golf

Merlin

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Subject:

Re: micro sd read write

· Posted: 25.04.2021 - 10:42 · #12

Hi Harry. You will have a problem if you pull the card during a write operation. Not sure if you do it during a read operation, but I think that will be OK for the card (maybe not for the application). Otherwise it should be fine. Pretty much the same as for a PC, but since write operations are immediate there is no eject. (Eject forces pending write operations to be completed and any locks to be released on a PC). But it being powered should not be an issue.

TheBeginner

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Subject:

Re: micro sd read write

· Posted: 25.04.2021 - 12:52 · #13

Guten morgen,

Also beim Lesen habe ich keine Probleme mehr, das haut 100% hin

Aber beim schreiben bin ich von WriteLn runter gekommen und nehme jetzt
Block_Write weil ich über Res sehen möchte das der Block auch gescjrieben
wurde.

Beim zurück lesen habe ich nach ein paar Zeilen das selbe Problem.

Gruß Frank

Code

//==============================
// Block Write
Procedure MMC_Block_Write;   //460
Begin
  Res:= 0;
  EmpfStr:= EmpfStr + #13+#10;
  www:= word(length(EmpfStr));
  ptr:= @EmpfStr;
  Inc(ptr);
  F16_BlockWrite(F, ptr, www, Res);
  Repeat
    nop;
  until res = www;
  SendeStr:= 'ok'; Sende_an_Host;
end;

Harry

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Subject:

Re: micro sd read write

· Posted: 25.04.2021 - 13:06 · #14

Hello Merlin,

I never pull out an SD card when a file is open. I wanted to know if you should turn off the voltage before pulling.

Regards
Harry

Merlin

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Subject:

Re: micro sd read write

· Posted: 25.04.2021 - 14:31 · #15

Hi Frank.

Edited! I was wrong in a few places!
There are a few issues here.

Code

www: = word (length (RECStr));

If you are using block write you need to include the length byte of the string, so

Code

www: = word (length (RECStr)) + 1;

Code

ptr: = @EmpfStr;
Inc (ptr);

This does not look right at all. Should it not be

Code

ptr: = @RecStr[1];

?

or maybe

Code

ptr: = @RecStr;
inc (ptr);

Code

  F16_BlockWrite (F, ptr, www, res);
  Repeat
    nop;
  until res = www;

if www<>res first time this will always fail because nowhere can either www or res change! In any event it will write garbage at the end of the line because www measures the length of RecStr but you are writing EmpfStr but without the length byte. So even if your write is successful it will be unreadable. But as long as you are writing less than 512 bytes (which you always will be) it will either succeed or fail. Hence you can use the boolean result to determine that. If it fails then it will always fail and there is no point in waiting for the record count to match.

So just

Code

  if F16_BlockWrite(F, ptr, www, Res) then

    if Res = www then
       SendeStr:= 'ok'; Sende_an_Host;
    else
      // whatever
    endif;
  else
     SendeStr:= 'fail'; Sende_an_Host;
  endif;

Regards

Merlin

TheBeginner

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Subject:

Re: micro sd read write

· Posted: 25.04.2021 - 16:59 · #16

Hello Merlin, I'm currently testing

Gruß Frank

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micro sd read write

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