On Thu, Dec 29, 2011 at 9:51 AM, Doug Carlson <carl...@cs.jhu.edu> wrote: > Howdy. I'm trying to use the BSLSKEY feature of the msp430f235 and I'm > running into some trouble. > > >From the datasheet (http://www.ti.com/lit/ds/symlink/msp430f235.pdf, table > 7 note 9), I want to initialize the word at 0xFFDE to 0 so that it's > slightly harder for me to accidentally wipe out the DCO and ADC12 > calibration constants stored in info segment A. > > This seems like a job for the const_sfrw macro. Here's what I tried (full > file here: http://pastebin.com/XvURBy69 ): > > #define BSLSKEY_ 0xFFDE > const_sfrw(BSLSKEY, BSLSKEY_); > BSLSKEY = 0; > > and here's the error that I get (full output/command here: > http://pastebin.com/4KZatFD0 ): > toggle.c:5:1: warning: data definition has no type or storage class > toggle.c:5:1: error: conflicting type qualifiers for ‘BSLSKEY’ > toggle.c:4:1: note: previous declaration of ‘BSLSKEY’ was here > > The macro gets expanded to this (full output/command here: > http://pastebin.com/UPSU7b4n ): > > extern const volatile unsigned int BSLSKEY asm("__" "BSLSKEY"); > BSLSKEY = 0;
This declares BSLSKEY as an external symbol, then declares an untyped symbol of the same name that is non-const but has an initializer, hence the errors. const_sfrw is used to replace references to peripheral registers in the assembly code with references to a linker-defined symbol. I don't think you could use it to define a load-initialized value. > What am I missing here? Is this even the right way to say "I want to > initialize this location to this value"? Where does 0xFFDE even get into > this mix? Does it go in the linker script? That seems to be where the other > SFR locations are defined. Address 0xFFDE is not mapped to any known linker section. You'd need a custom memory.x to define the one-word region, then override the msp430.x* to add an output section for it, and either put the value into the linker script or use an asm file to place it as is done with crt0ivtbl.S. Or you may be able to combine it all into one line in the linker script without any special regions. Regardless, I think you need to do this in a custom linker script. Peter > Thanks in advance, > Doug Carlson > > ------------------------------------------------------------------------------ > Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex > infrastructure or vast IT resources to deliver seamless, secure access to > virtual desktops. With this all-in-one solution, easily deploy virtual > desktops for less than the cost of PCs and save 60% on VDI infrastructure > costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox > _______________________________________________ > Mspgcc-users mailing list > Mspgcc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/mspgcc-users > ------------------------------------------------------------------------------ Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex infrastructure or vast IT resources to deliver seamless, secure access to virtual desktops. With this all-in-one solution, easily deploy virtual desktops for less than the cost of PCs and save 60% on VDI infrastructure costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox _______________________________________________ Mspgcc-users mailing list Mspgcc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mspgcc-users
