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?
已解决! 转到解答。
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