I'm working with the MK64FN1M and I am having issues with SDIO block transfers using CMD53 (command). Up till now I have had no problems sending commands and byte transfers. I am using 1-bit at 400 KHz baud, 1 block, 128 bytes, 128 >> 2 for the watermark, and card detect disabled on both ends.
I've connected a scope and can confirm that data is being sent and received on the SDIO DAT0 pin. I can also confirm that the command sent is correct on the command pin and that the data transmitted or received is the correct binary data that I am sending or expecting to receive.
The issue is that the data being sent is only around 14 bytes + the 2 byte CRC. When receiving data, again, the clock only runs long enough to receive 16 bytes and afterwards the IC holds the data line low.
Is this a flaw in the MK64FN1M0VLL12? Am I missing anything or is there a workaround?