Accessing External Memory Devices

Dan,

Actually, through some research, putting a value in that dialog does more harm than good.

If I specify a range in there, I get :

*** ERROR L107: ADDRESS SPACE OVERFLOW
    SPACE:   DATA
    SEGMENT: STACK
    LENGTH:  00000490H
*** WARNING L23: UNRESOLVED EXTERNAL SYMBOLS
*** ERROR L128: REFERENCE MADE TO UNRESOLVED EXTERNAL
    SYMBOL:  ?C?INIT
    ADDRESS: 0000010CH
Program Size: data=1172 const=0 code=304
Target not created

Dan,

Actually, through some research, putting a value in that dialog does more harm than good.

If I specify a range in there, I get :

*** ERROR L107: ADDRESS SPACE OVERFLOW
    SPACE:   DATA
    SEGMENT: STACK
    LENGTH:  00000490H
*** WARNING L23: UNRESOLVED EXTERNAL SYMBOLS
*** ERROR L128: REFERENCE MADE TO UNRESOLVED EXTERNAL
    SYMBOL:  ?C?INIT
    ADDRESS: 0000010CH
Program Size: data=1172 const=0 code=304
Target not created

Are you only running this in the simulator and not the real target hardware?

Dan,

I have taken a more simplistic approach for the time being.

I have created a new projeect, with my definition of:

#define MY_REG1 (*(volatile unsigned char *)0x83000000)

0x00000608  B500      PUSH      {LR}
    30:   MY_REG1 = 1;
    31:

To answer original question, this is just in simulator

Nothing after that?

Can you show more disassembly context?

0x00000606 E7F1 B 0x000005EC
27: int main (void) {
28: unsigned int j; /* LED var */
29:
0x00000608 B500 PUSH {LR}
30: MY_REG1 = 1;
31:
0x0000060A 2101 MOV R1,#0x01
0x0000060C 4813 LDR R0,[PC,#0x004C]
0x0000060E 7001 STRB R1,[R0,#0x00]
32: IODIR1 = 0xFF0000; /* P1.16..23 defined as Outputs */
33:
0x00000610 4913 LDR R1,[PC,#0x004C]
0x00000612 4814 LDR R0,[PC,#0x0050]
0x00000614 6001 STR R1,[R0,#0x00]
34: init_timer();

Much better. Thank you.

0x00000606 E7F1 B 0x000005EC
27: int main (void) {
28: unsigned int j; /* LED var */
29:
0x00000608 B500 PUSH {LR}           ;Just saving some processor context there.

30: MY_REG1 = 1;
31:
0x0000060A 2101 MOV R1,#0x01        ;Loading R1 with the value to be written.
0x0000060C 4813 LDR R0,[PC,#0x004C] ;Loading R0 with the address to write to.
0x0000060E 7001 STRB R1,[R0,#0x00]  ;Performing the byte write.

Dan,

Another thing I just noticed is that if I stored this in the target options

start of 0x83000000, and size of 0x4,

the compiler gives me this:

*** ERROR L107: ADDRESS SPACE OVERFLOW
    SPACE:   DATA
    SEGMENT: STACK
    LENGTH:  00000490H
*** WARNING L23: UNRESOLVED EXTERNAL SYMBOLS
*** ERROR L128: REFERENCE MADE TO UNRESOLVED EXTERNAL
    SYMBOL:  ?C?INIT
    ADDRESS: 00000104H
Program Size: data=1172 const=0 code=296
Target not created

"Any idea why it doesnt like the smaller size?"

The only thing I can think of is that the mapper is designed to deal with larger chunks, for example >=256-bytes.

My Linux kernel rounds everything up to 4KiB pages ;-)

Dan,

Thanks again for your help today.

I think this is enought to go on for now.

If I need to specify a bigger chunk, its not too much of a big deal :) Im going to use it or im not, end of that.

Again, thanks for the assistance.

This beginning embedded guy really appreciates it :)

You bet. Have fun!