hi, at the code blow i want to toggle PA13 for using mmc cs, but when i toogle it in loop it will be done but when i toggle it once time no toggle, download my code from attachment and tell me where is the problem, i used cs1 for mmc but init cs0 for spi to spi send data, beacuse i must change cs value manually. thanx a lot.

I sure wouldn't be using this OR type action on the Clear and Set registers.

AT91C_BASE_PIOA->PIO_CODR |= (1 << 13);

Just write the single bit you want to change the state on, don't do a read-modify-write, it's pointless and somewhat dangerous.