Dear,
Writing a 32 bit value can be easily done with a NIOS core.
For example:
You make use of a SRAM which has a 32bit databus. You can access this 32b
bus with your NIOS core for example by use of a 32 bit parallel IO bus
(GPIO 32 bit), called SRAM_DATABUS.
Writing to this bus, you can easily do with following pointer instruction. The address is defined in your system.h file.
volatile unsigned int * data = (unsigned int *) (SRAM_DATABUS_BASE);
*data = 0xFFAAFFAA;
The same procedure you can use for writting the SRAM CSn, WRn, RDn, ....
Of course, take into account timigs (setup time, hold time,...) of you SRAM device.
Regards
Karel