Best way to interface my CPU

You can only trigger on either the 'write' or the 'read', if you set a trigger condition for both, they get 'anded' and as read and write are mutually exclusive signaltap won't get triggered.

Secondly, there may be a pitfall in the code, I have no idea how good the compiler optimizes the code, but it may well be that although you have a while loop the address specified only gets written once. As a consequence it may write only once, and maybe you started the signaltap after starting the CPUy

You may try something like:

#include <stdio.h>
void main()
{
    volatile int * memory;
    int i ;
    memory = 0x882040;
    i = 0 ;
    while (1)
    {
        *memory = i++ ;
    }
}

The volatile attribute tells the compiler that the write (or a read) has a side-effect and thus it can not optimise that operation.

If you do have a data cache you have to set bit31 of the data to 1 to bypass the data cache.