Hello,
We are integrating an i.MX 8QuadMax and are experiencing intermittent failures of SanDisk brand 32GB microSD cards in our development units.
With a protocol analyzer on bootup (this microSD card is the OS boot source) and a *failed* card, I see the i.MX 8 send a CMD0 (reset), then CMD8 (check supplied voltage), then a CMD55 (APP_CMD) and ACMD41 (send operating condition register). The CMD55 and ACMD41 commands are continuously sent until the i.MX 8 resets itself after about 300mS. Bus analysis shows that the ACMD41 response "Busy Status" bit is never set, therefore the card has not completed initialization and the i.MX 8 resets before it ever does.
Questions:
1. The SDIO Physical specification says that the SDIO controller should wait for the "Busy Status" bit to be set for at least 1 second, yet the i.MX 8 resets before then. Why? Can this be changed?
2. Has anyone else experienced SD card failures like this using i.MX 8 processors? Our previous generation product with an i.MX 6 processor did not exhibit this issue.
