I wrote post about SD clk several day ago (http://www.cypress.com/?app=forum&id=167&rID=110967)
I head something of the thread, but I still can't solve it.
I tested two class of SD card made by Transcend. for one ting is Class 10, for another thing is UHS-1(x300)
I set a gpio for working 1.8v on the board. there are two SD card is not working.
SD clk works only 400Khz.
but I tested another SD card made by SAMSUNG. the sd card is working on the 1.8V
so I tested SDR mode and DDR mode. but SD clk working 50.4 Mhz Fixed.
This is result of the test.
VIO2/VIO3 is 3.3V, DDR mode: 14MB/s read. The clk works 50.4 Mhz.
VIO2/VIO3 is 3.3V, SDR mode: 14MB/s read. The clk works 50.4 Mhz.
VIO2/VIO3 is 1.8V, DDR mode: 14MB/s read. The clk works 50.4 Mhz.
VIO2/VIO3 is 1.8V, SDR mode: 14MB/s read. The clk works 50.4 Mhz.
The result is no changed to change Voltage or SDR/DDR mode.
What I miss it ???
Please find the updated response in the orginal Thread.
- Madhu Sudhan