I have a problem for which I can't find the solution in previous topics.

I'm using a microcontroller to read data from a Kodak 2GB Micro SD Card. I want to write a minimal driver in SPI mode, no need to do writing or formatting operations, just read some files.

I can see those signals on a 4 channel scope: CS, MOSI, MISO, CLK.

I do the following:

  1. I send 100 bytes at 100KHz, with MOSI and CS high.

  2. I send CMD 1, no argument, response type R1 returns 0x1, correct.

  3. I send CMD 8, arg=0x1AA, response type R7 returns 0x1+ arg 0x1AA, correct.

  4. At this point every command returns 0x5 at the 4th byte of the command. In other words, before the 6 bytes command is completely issued.

Any explanation for that?

  • \$\begingroup\$ after sending the CMD8, you need to receive 8 bytes of data from SPI. isn't it? \$\endgroup\$
    – MaNyYaCk
    Commented Jul 26, 2017 at 18:37
  • \$\begingroup\$ I would say 6 bytes:dummy+response+4bytes(echo of argument). \$\endgroup\$ Commented Jul 26, 2017 at 23:23
  • \$\begingroup\$ Oops. Yeah. My bad \$\endgroup\$
    – MaNyYaCk
    Commented Jul 27, 2017 at 0:09

1 Answer 1


In the last hour i did other test ... Seems solved. The difference is that before,when i wanted to to bang out the clock pulses necessary for read each command answer,i did not pay particular attention on the data sent on MOSI ,it was 0x00. Now i use 0xFF and everything works fine.


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