Hello.
I'm using DM8168 on our custom board.
Sometimes I saw an error message through the UART console, so I measured about SD card signals. (I think the message was "mmcblk0p1 I/O error...")
In result, SD_CLK to SD_CMD timing was not as same as SD_CLK to SD_DATx. Please refer attached waveforms.
SD_CMD transition is near the CLK edge, so I think it did not meet the setup time.
I corrected this error by add a capacitor(33pF) to the SD_CLK signal.
But I don't know whether it best countermeasure...
Software environment is EZSDK 5.02.
Please tell me, if you know better countermeasures.
Incidentally, SD card is directly connect to the DM8168.
(1) Ch2=SD_CLK, Ch3=SD_CMD (This waveform is after adding a capacitor.)
(2) Ch2=SD_CLK, Ch3=SD_DAT3 (This waveform is after adding a capacitor.)
Regards,
-Miyazaki
