IMX8M Plus boot and read from SD Card

[www1519]

Hi! NXP Engineer

This project is designed to use the IMX8M Plus platform, and include the circuit for SD Card.

In my design, the Load Switch of the PCA9450C is not used for the power supply of the SD Card,

and one DC-DC 3.3V power supply (the reason is relatively far away) is used.

However, When the PCB board is debugded, found that if the load Switch circuit of the PCA9450C

is not used, the IMX8M Plus cannot boot from the SD Card and cannot read the SD Card,

and the  driver for SD Card is also placed in the kernel, and then difficult to design change.

However, neither the manual for the IMX8M Plus nor the PCA9450C, 

the Load Switch must not be used for SD Card. Can you tell me what caused it,

and why the Load Switch function must be used?

Best regard. Thank you!

[joanxie]

how did you connect the pins if you don't use SW? pls share the schematic, I suggest that you can use this when you use PCA9450

[www1519]

Hi! Mr. joanxie @joanxie 

The schematic is below. In my design, SD Card‘s PS is from DCDC3.3V.

R0935,R2133,R2137 is DNP in my design.

Why  the LD must be used ?  Pls tell me, Thanks a lot.

[joanxie]

I don't they you must use it, switch loader has overcurrent protection and short circuit protection, so we suggest that customer can use it, refer to the data sheet, if you don't use SWIN and SWout, Leave it floating if not used, and as you said you couldn't boot up from sd card when you didn't use it, what message did you get?

[www1519]

Hi! Mr. joanxie @joanxie 

Thanks for your reply.

The log is as the following.Pls reference.

best regards.

  

[joanxie]

what do these pics stand for? the pic1 shows the board couldn't boot, but pic2 shows the board boot up successfully? could you share the whole logfile? if you don't use switch load, did you leave float SWIN and SWOUT?

[www1519 · Accepted solution]

Hi! joanxie @joanxie 

I'm very sorry for the late reply.

If use the Load Switch Power, can boot from SD Card.

Thank you for support.

Best regard!