Dear all,
we want to use a graphical diplay connected to the external address/data bus of an ADuC832. The startaddress is wired to 0x8000.

The function write_lcd() should write cmd_data to the display. Dependend on the data_type a port pin is set or cleared.

If i simulate the code in the uVision2 the data is always written into idata and not into xdata. The compiler sets r3=0 at the beginning of the function and when writing to the memory it checks if this reg is set to 1.



#define DISPLAY_START_ADDR 0x8000

void write_lcd(unsigned char data_type,unsigned char cmd_data) {
unsigned char *display;
if (data_type==COMMAND)
DD_A0_0();
else
DD_A0_1();
display=(unsigned char*)DISPLAY_START_ADDR;
*display=cmd_data;
}


How can i set the address of a pointer to a specific address in external memory area?

regards,
Markus