Hello!
I am just starting my travel through MSP and GCC wonderland, so excuse
me if this is a really dumb question...
I have just compiled my own toolchain (running Debian Linux "unstable"
on amd64) and am now using
msp430-gcc (GCC) 4.7.0 20120322 (mspgcc dev 20120911)
on a msp430f5438a (-mmcu=msp430f5438a).
I have a small program which I translate using "-mmemory-model=medium".
Inside the program I have the following (global) declaration:
#define LCD_CLEAR_CMD 0x04
static unsigned char LCD_CLEAR_COMMAND[] = {LCD_CLEAR_CMD, 0x00, 0x00};
When I compile it this way, attach GDB to mspdebug then I can see that
LCD_CLEAR_COMMAND ends up at address 0x1c00 - fine. BUT at 0x1c00 I find
the following content:
(gdb) x/bx 0x1c00
0x1c00: 0x00
0x1c01: 0x04
0x1c02: 0x00
which is wrong, it should be 0x04 0x00 0x00 !?
If I declare it as const:
static const unsigned char LCD_CLEAR_COMMAND[] = {LCD_CLEAR_CMD, 0x00,
0x00};
it ends up in another segment at 0x62f6 and the content is correct:
(gdb) x/bx 0x62f6
0x62f6 <LCD_CLEAR_COMMAND>: 0x04
0x62f7 <LCD_CLEAR_COMMAND+1>: 0x00
0x62f8 <LCD_CLEAR_COMMAND+2>: 0x00
What is going on here? Or am I doing something wrong or unexpected here?
Well, defining it const might make sense anyway, but I would expect the
other way at least to work too, even if suboptimal.
Another severe issue is that as soon as I compile the application to use
20 bit data (-msd20) or use -mmemory-model=large the controller enters
an uncontrollable state after reset, i.e. mspdebug wrongly reports a
blown fuse and it can be recovered pressing and holding the reset button
on the msp board and releasing the button as soon as mspdebug tries to
open the device.
Sooner or later I will have to use the 20 bit data area - as you can
guess from the above command I am using a LCD and need to store fonts
and some bitmaps...
Did anyone else already successfully use 20 bit data with mspgcc?
I should probably also mention that "large" did work in the beginning as
long as the application was *really* small. When it grew a little (I am
now at
# msp430-size gccfwtest.elf
text data bss dec hex filename
1845 0 1348 3193 c79 gccfwtest.elf
) it started to go haywire.
Strange strange...
Cheers
nils
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