problem with intilizing sd card.

[MaxBoyman]

there was a common problem with your library and all of the programs which i wrote in the past and that was problem initilizing sd card in first definition step.
if (!SD.begin(SD_CS_PIN)) {}
was randomly true.
i had tested this situation with lots of SD card modules and arduino boards. for example Mega 2560, Uno, Due.
after lots of searches i found the problem can be solved with adding a simple delay(150) to the file SdSpiCard.cpp in line 141 which is :
while (cardCommand(CMD0, 0) != R1_IDLE_STATE) {
delay(150); //Added line
if (isTimedOut(t0, SD_INIT_TIMEOUT)) {
error(SD_CARD_ERROR_CMD0);
goto fail;
}
}
this solved the whole problem. please investigate this and add the line if it's true.

[greiman]

I tried a number of SD cards and found problems with older cards.

Your delay helps with some cards but not others. I made several mods including your delay and all the older cards I have seem to initialize now.

[greiman]

I have done more testing and found the real problem.

An SD card indicates busy, when not doing a data transfer, by holding MISO low. Before some older cards are initialized, they hold MISO low or they tri-state MISO and it may appear low.

SdFat has a test for busy which causes a long delay for these cards. An SD card will accept CMD0, the software reset command, even if it is busy.

At about line 212 of SdSpiCard.cpp I added a test for CMD0:

  // wait if busy unless CMD0
  if (cmd != CMD0) {
    waitNotBusy(SD_CMD_TIMEOUT);
  }

I removed the delay that I added at about line 146.

// delayMS(SD_CMD0_DELAY);

I tested with about 20 old cards. They all Initialize as fast or faster than with the delay. None of the cards fail to initialize.

Please try this mod and let me know if it works with your cards.

[MaxBoyman]

i'm testing new version 1.0.12. are these new lines changed in version 1.0.12?

[greiman]

The new lines are changes to 1.0.12.

[greiman]

I have been testing SD shields and breakouts. It has been years since I did this.

Most don't comply with the SD spec:

RDAT and RCMD are pull-up resistors protecting the CMD and the DAT lines against bus floating when no card is inserted or when all card drivers are in a high-impedance mode.
The host shall pull-up all DAT0-3 lines by RDAT, even if the host uses the SD Memory Card as 1 bit-mode only in SD mode. Also, the host shall pull-up all "RSV" lines in SPI mode, even though they are not used.

RDAT/RCMD should be 10-100 kΩ.

Without the pull-up resistors, some cards appear busy before being initialized since all DAT lines are floating. Also when no card is inserted, the lines may look like a busy card.

Without pull-ups, cards may not go into low power idle mode and draw excess current. Normally an idle card draws about 100 micro-amps while active cards draw 20 or more ma.

Edit: Most of the problems can avoided by adding a pull-up on MISO like this:

See this article.

[MaxBoyman]

I will check if my SD module have it on the board.

[greiman]

I have posted 1.0.13. It has two subtle changes that are a workaround for the MISO pull-up problem.

These changes also seem to help with cards that don't strictly follow the SD spec.

I no longer need a loop for the CMD0 reset or CMD8 to enable SDHC cards.

I built a test SD module with switchable pull-ups and instrumented the code plus used a hardware logic analyzer to understand the problem.

I hope I have not introduced new problems.

[MaxBoyman]

i checked the module for the resistor which you told that it should be at MISO. it is there, but the problem is exists in some cases. i used your library for 5 industerial grade projects and this problem is the only one i have in these projects. this library is good but please help me fix this problem.

[greiman]

Do you have any other SPI devices?

Does your SD module have level shifters? You should only use level shifters with 5V AVR boards.

Be sure to use SdFat 1.0.13 for the following.

Run the SdInfo example and post the error codes if it fails.

Also run the SdInfo example with no SD. It should produce this result:

type any character to start
error: cardBegin failed
SD errorCode: 0X20,0XFF

The 0XFF shows that the MISO pull-up is working.

With a MISO pull-down the result is:

type any character to start
error: cardBegin failed
SD errorCode: 0X20,0X0

[greiman]

I added one more improvement to card initialization in 1.0.14.

Some older cards will not reinitialize if they are in transfer mode. I added retry with code to end transfer mode.

Have you tried the SdInfo test?

[MaxBoyman]

Yes i tried sdinfo without sdcard in module. And the result was: 0x20,0x0
What's it means?

[greiman]

The 0X0 with no card means that something is holding MISO low while the CMD0 response is read.

MISO may be floating low. Few SD modules have a MISO pullup.

What SD module/shield are you using?

What Arduino or third party board are you using?

[MaxBoyman]

Arduino Mega2560.
can't find the sd card brand but i am trying to add a pull-up resistor. what is the resistor amount which can suit it best? because you said 10-100k which is better?

[greiman]

First, do you have other SPI devices? These can interfere with the SD module.

There are some SD modules that have a level shifter on MISO. A pull-up will not help with these.

Most modules with pull-ups use 10k.

You can do a test by adding an external resistor from MISO to V3.3 or V5. It should change the result of SdInfo to 0X20, 0XFF.

You probably no longer will need the pull-up on MISO with SdFat 1.0.14. I have tried to provide workarounds in the code.

[MaxBoyman]

no there is no spi devices other than sd module.
i am updating the library and testing. i will let you know if problem fixed.