Accelerating write speed on sd card in LM4F232H5QD
I need to write and retrieve data at high speed in a SD / HD seeing the sources of stellaris in "mmc-ek-lm4232h5qd.c" I noticed that the maximum speed is set at 12.5 mhz
set_max_speed void (void) { unsigned long i;
/ * Disable the SSI * /
ROM_SSIDisable (SDC_SSI_BASE);
/ * Set the maximum speed to half the system clock, with a max of 12.5 MHz * /
i = ROM_SysCtlClockGet () / 2;
if (i> 12500000)
{ i = 12500000; }
/ * Set the SSI0 port to run at 12.5MHz * /
ROM_SSIConfigSetExpClk (SDC_SSI_BASE, ROM_SysCtlClockGet (), SSI_FRF_MOTO_MODE_0, SSI_MODE_MASTER, i, 8);
/ * Enable the SSI * /
ROM_SSIEnable (SDC_SSI_BASE); }
With the clock at 80 MHZ setting as folow ROM_SysCtlClockSet (SYSCTL_SYSDIV_2_5 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);
What is more safe speed possible to configure SSI with the clock on 80 mhz
I can simply change this line ?
i = ROM_SysCtlClockGet () / 2;
if (i> 12500000)
{ i = 12500000; }
