Hi,
We need some advice in troubleshooting AM335x SD card communication.
Our customer's prototype boards based on AM3352 has some issue with reading the SD card.
out of 10 boards, 2 boards have the issue of reading file (Config file) from the SD card.
Out of these 2 boards, one board can be recovered by removing the SD card and inserting it back,
but the second board has some issue in the voltage level of CMD and D0-D3 lines.
In the normal boards, CMD and D0-D3 line's rise time and the voltages are stable
but in bad board the CMD line voltage fluctuates from 2.7V to 3.3V and the rise time
of these lines is bit slow compared to the normal boards.
Normal Board:
Bad Board:
VMMC = VDD, D0-D1 lines are also same.
It seems the CMD and data lines are being pulled(around 12Kohm to 15Kohm) by AM335x.
The SD card circuit connection is same as the StarterKit schematics with additional
GPIO connection for WP(Write Protect). CMD and Data lines are pulled up with 10K resistors.
Please let us know if there is any suggestion on troubleshooting this issue,
and if there is any possibility that AM335x's pulling MMC lines. Software used = Starterware.
Best Regards
Paddu
