problems for M483 SD and USB

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kine001
Posts: 6
Joined: 04 Aug 2019, 18:01

23 Aug 2019, 11:54

Hi,

1, As for M483SIDAE SD controller, we can't get the correct data from SDHC using DMA read
for SD interface, we only use SD0, so we connect the SD0_DAT0~3 and SD0_CMD, SD0_CLK to SD slot, but let SD0_nCD float
when initializing, i set the CARD_DETECT_FROM_DAT3, and disable the CARD detect interrupt, and the SD card has been recognized
for SD2.0 card. But the CRC16 error occurred when reading SCR information from SD card using CMD51, the command has been sent to SD card
successfully, and the DMA reading has done, but the datas read are not correct, just as shown below
sd dma crc16 error for cmd51.png
sd dma crc16 error for cmd51.png (317.92 KiB) Viewed 348 times

Why the DMA can not read the correct data from SD card?

2, for SDXC type SD card
for now, most SD card are SDXC type, could M483SIDAE support SDXC card? Even used the SDXC card as SDHC.

3, for USB
when i trigger the DMA transfer, it always stop at waiting the DMA transfer done interrupt,so i have to add the timeout
mechanism for USB DMA transfer,i'm puzzled why this could be happened?
finnally, for USB read/write speed, in my test, the read speed is 13.5MB/s, and write speed is 6.5MB/s, but in the USB2.0
standard, the speed could be up to 480Mbps, which speed could M483SIDAE's USB read/write reach? And is it normal for write speed is half of

read speed?

Thanks a lot.

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