AnsweredAssumed Answered

One SD Card doesn't boot properly (rejects everything after CMD0)

Question asked by bassmati on Mar 23, 2018
Latest reply on Mar 26, 2018 by bassmati



I'm currently developping a SD Card driver, and after some hard work, I got to a point where everything works pretty well. However, I have this one SD card that doesn't boot properly, while 3 others work great. I'm working on a STM32F070, accessing the microSD card with SPI, clocked at 12MHz.


The error occurs at the very beginning : I send CMD0, the card actually sends the correct response (0x01), but then, when sending CMD8, the command is rejected (I get a 0x7F R1 response). I tried sending CMD0 again instead, same result. I raise CS, send 8 clock bits, and lower CS again between the two commands.


The 3 cards that do work are:

- Standard capacity 2G, with no speed class indication

- HC 4G C10

- HC I 4G C4 (this one is strange : UHS-I bus, but low speed class C4)


The one that doesn't work is a HC I 16G U1.


I read a lot, I tried a lot, but I can't figure out why the card would accept CMD0 and reject everything else after that. Of course, I tested the card on a standard reader and it works.


Any suggestion would be appreciated