TBox emulated SDIO by FlexIO question: 1 bit or 4 bit mode?

[Li_Chen]

I have reviewed S32K344 TBox reference design from S32K3 Automotive Telematics Box (T-Box) Reference Design Board | NXP Semiconductors. At very beginning, I saw 4 Data lines(DATA0~DATA3) are set as FlexIOs and connect to SD card socket. I thought it's 4 bit data transfer mode for SD/MMC. However, after checking the TBox reference code, I see it's in SPI mode(1 bit data transfer). Can you confirm this?

From the RM, I see the max SPI clock over FLEXIO config are only 20MHz, I guess there is no point to enable SD/MMC 4 bit transfer mode over FLEXIO(even I don't know how), but instead, using LPSPI to achieve higher data throughput?

[danielmartynek]

Hi @Li_Chen,

Which reference code do you mean?

Thanks,

BR, Daniel

[Li_Chen]

The reference code are from S32K3-T-BOX Reference Design - BSPs, Drivers and Middleware(https://www.nxp.com/webapp/Download?colCode=S32K3-T-BOX-BSP)

[danielmartynek · Accepted solution]

The problem is that the FlexIO RTD driver does not support 4bit SPI / SDIO protocol.

Theoretically, it can be supported, that's why this is implemented in HW.

Regards,

Daniel