Does bootloader detect CD/DATA3 micro sd card?

[MehmetAliIpin]

Dear Sir,

We have an i.mx6 board which is based on mx6sabresd kit. We can download u-boot with USB loader.

and I modified u-boot to detect and run SD card for 4 bit interface.

Our SD card is micro 4 bit wide SD and its card detect pin is also different (CD/DATA3) from origininal kit design. For the small PCB sizes, there is no boot config switches or resistors also. Therefore we will program the fuses to processor to boot from SD card, (or (Q)SPI flash).

I wonder if mx6 boot loader firmware checks for special sd card detect pins and/or if not find a card, does it check CD/DATA3 pins status for u-boot code? do we need any pull up/pull down resistor for this pin to be detected?

Could Anybody help?

Thanks and best regards.

Mehmet Ali

[mehmetipin]

Dear Igor

Thank you very much.

Best regards.

[mehmetipin]

Dear Igor,

I checked the boot_cfg[7:5] bits of efuse configuration register, see that 4 bit is supported,

does it mean, boot loader will not check the CD/DATA3 pin in 4 bit mode (there is no special card detect pin in 4 bit SD card) , and continue to check other u-boot loading tasks from 4 bit SD card as shown in figures 8-10 thr. 8.15 in ref manual, if we program the efuse boot register accordingly?

Best regards

[igorpadykov · Accepted solution]

Hi Mehmet

yes ROM does not check CD/DATA3, CD is only checked for

interfaces described in Table 8-17. SD/MMC IOMUX pin configuration

i.MX6DQ Reference Manual or relevant processor Boot Chapter Reference Manual.

Best regards
igor

[lokesh]

Here is what I have checked on the board that I have. I have flashed u-boot on SD Card and the u-boot boots fine, irrespective of the Carrier Detect (CD). However, u-boot does have MUX setting of the GPIO pins for SD Card Detect and it will be used when it will check the file system for booting kernel.  If the SD Card Detect is not set properly, it will not list the file system ( for example, when  using ext2ls).

I have put some more details in the link below, if you want to check

Using SABRE-SD u-boot on Sabre Lite for i.MX6 | Reference Designer  

[MehmetAliIpin]

Dear Vikas,

Thank you very much for your answer.

Best regards.

[igorpadykov]

Hi Mehmet

ROM does not check CD/DATA3, CD is checked for

interfaces described in Table 8-17. SD/MMC IOMUX pin configuration

i.MX6DQ Reference Manual or relevant processor Boot Chapter Reference Manual.

http://www.nxp.com/docs/en/reference-manual/IMX6DQRM.pdf

Best regards
igor
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