SD card controller can just read data using 1 bit SD mode.
I have written this core for NIOS2 CPU, Cyclone, but I think it can works
with other FPGA or CPLD. Better case for this core is SD clock = 20 MHz and
CPU clock = 100 MHz (or in the ratio 1:5). If you have a wish you can achieve this core.
Good luck
MSP-FET430P410 Demo - Timer_A Toggle P5.1, CCR0 Contmode ISR, DCO SMCLK
Description Toggle P5.1 using using software and TA_0 ISR. Toggle rate is
set at 50000 DCO/SMCLK cycles. Default DCO frequency used for TACLK.
Durring the TA_0 ISR P5.1 is toggled and 50000 clock cycles are added to CCR0. TA_0 ISR is triggered exactly 50000 cycles. CPU is normally off and
used only durring TA_ISR.
ACLK = n/a, MCLK = SMCLK = TACLK = DCO ~ 800k